Systematic Survey on Optical Microscope Technology in Japan

4

Chikara Nagano
 Abstract
Microscopes are tools for observing infinitesimal objects that are invisible to the naked eye. Invented in the Dutch Republic in thelate 16th century, handmade microscopes were used to discover cells and microorganisms in the 17th century, thus unveiling the
microscopic world. Manufacturers of microscopes began to appear mostly in England in the 18th century, but microscope
performance did not significantly improve until the second half of the 19th century. At the end of the 19th century, the German andAustrian lens manufacturers suddenly became the leading optics companies in the world, building on the foundation laid by Ernst
Abbe, who established a theory of image formation and a method of designing lenses, and also drastically improved theperformance of objective lenses. This improvement in the performance of microscopes led to further developments in medicine,especially bacteriology, and in addition to major achievements such as the discovery of the pathogens that have continuously
plague mankind and ways of dealing with them, microscopy has made substantial contributions to the development of all other fields
of science and industrial technologies.
In Japan, there was an increase in the importation of microscopes from the middle of the Meiji era, which were mainly used in the
medical and sericulture industries, and this led to the appearance of Japanese who endeavored to make Japan’s first microscopes
during the period spanning the end of the Meiji and the beginning of the Taisho eras. Although reproducing foreign microscopes
posed challenges, especially with regard to the production of high power objective lenses, which is the ultimate sign of high quality,
this was overcome with the zeal and spirit of the craftsmen. Subsequent improvements and technological developments improved
the quality of Japanese microscopes, paving the road to birth of this industry in Japan. The post-war period saw the emergence of anumber of microscope manufacturers. Building on the base of pre-war technological standards, and due to the establishment of theJapan Microscope Manufacturers’ Association and joint efforts by industry/government/academia in terms of technological researchand standardization, slowly but surely, further improvements were made in terms of the level of functionality and performance. This
eventually led to the development of research microscopes, compound microscopes and high-class microscopes for photography,
and with improvements in quality control and customer service, Japanese microscopes have come to be recognized throughout theworld, with annual exports to Europe and the US increasing year-on-year due to their superiority in terms of cost-performance. Thiswas made possible not only by the passion and tenacity of the researchers and engineers who worked for the manufacturers, andthe skill of the manufacturers, but also by thanks to the maturing of the domestic industrial environment in terms of lens design
techniques, optical glass quality and electronics technologies, etc., and the support and expectations of personnel engaged in
cutting edge research as users. Since the late 1970s, the top two leading microscope manufacturers in Japan have progressively
developed new optical systems, and due to significant improvements in performance and usability with the introduction ofelectronics technologies and the increase in the number of units/accessories, both companies have now come to rank alongside thetwo German manufacturers as the top manufacturers in the world.
Thus the history of optical microscopes has been a tireless struggle to make visible the invisible. Beginning with the performanceincrease obtained in objective lenses by the use of geometric optics, a variety of methods of observation were established throughthe application of physical optics; interference, diffraction, polarization, and fluorescence, etc., which contributed greatly to theprogress of science and technology, as well as industrial development. Many specialized types of microscopes exist; inverted
microscopes, stereoscopic microscopes, metallurgical (or industrial) microscopes, and so on, and these continue to evolve. Thereexists a limit, imposed by the wavelength of light, on the resolving power of optical microscopes that rely on visible light, and as theperformance of objective lenses had also all but reached its limit, many researchers held the view that further development of optical
microscopes could not be expected, especially in light of the development of electron microscopes. However, new forms of optical
microscope, such as the laser scanning microscope, emerged in the latter half of the 1980s, and optical microscopes made acomeback as the mainstay of cutting-edge research, such as bio-imaging, in light of their advantages, which include the ability todynamically observe living biological specimens. Even more advanced multi-photon excitation laser scanning microscopes andsuper-resolution microscopes have appeared, and further progress is expected.
In this paper I will report on the history of such optical microscopes and the spread of the technology in Japan, paying particularattention to optical technology for objective lenses. Following the introduction that is Chapter 1, I will then report on the fundamental
principles of optics and microscopes in Chapter 2, the history of microscopes from their invention up until the 19th century in
Chapter 3, the birth and growth of Japanese microscopes with particular regard to the spread of upright biological microscopes in
Chapter 4, the history and development of the various microscopy techniques in Chapter 5, the history and development of thevarious types of microscope in Chapter 6, the development of optical technology for microscopes with particular regard to thedevelopment of objective lenses in Chapter 7, the latest optical microscopes in Chapter 8, and present a conclusion and a
discussion in Chapter 9. Mechanical and electronic design and production, which are other important elements of optical
microscope technology, have been omitted from this report as they are outside the Author’s area of expertise.
The theory and application of the optical microscope has been the base for much Nobel prize-winning research. The awarding of
the 2014 Nobel Prize in Chemistry was connected with the development of super- resolution microscopy, and even in Japan the
optical microscope has played a part (amidst other important research) in securing the Nobel Prize in Physiology or Medicine. Thus
the optical microscope has been a base for combining optical technology, electronics technology, and information technology, etc.,
to create technology and equipment for visualizing vital phenomena that were previously thought to be impossible to visualize.
Researchers have long desired to have the ability to observe the invisible, and the struggle to push the boundaries of optical
microscopy will undoubtedly continue. I look forward to seeing Japanese microscope R&D and manufacturing technology continue
to lead the world in incorporating new theories, technologies and materials to meet the needs of the biosciences and other fields ofresearch.

 Profile

Chikara Nagano
Senior Researcher, Center of the History of Japanese Industrial Technology, National Museum of Nature and Science
1974:

Graduated from Osaka University School of Engineering,
Department of Applied Physics
1976: Completed Master’s Degree program in Applied Engineering at
Osaka University Graduate School of Engineering
Started working for Olympus Optical Co., Ltd. (now Olympus
Corporation), working on research and development of
microscope optical systems in the optical research anddevelopment department
1996: Assigned to Olympus Japan Co., Ltd.
1999: Assigned to Olympus Research & Development Head Office
2005: Appointed as Chief Secretary of Japan Microscope
Manufacturers’ Association
2016: Senior Researcher, Center of the History of Japanese Industrial
Technology, National Museum of Nature and Science
1994-2016: Expert on ISO/TC172/SC5 (microscopes and endoscopes)

 Contents
1 Introduction ......................................................................2
2 Fundamental Principles of Optics and Microscopes 1) 2) 3) .4
3 Invention and Development of Microscopes 1) 2) 3) 4) 5) ......18
4 Birth and Growth of Japanese Microscopes....................22
5 Development of Various Microscopy Techniques 1) 2) 3) ...34
6 Development of Various Types of Microscopes ..............47
7 Development of Optical Technology for Microscopes .....60
8 The Latest Optical Microscopes .....................................79
9 Conclusion and Discussion ............................................83

1

Introduction

In March 2015, the National Museum of Nature andScience held a planned exhibition, “A Century of Japanese
Microscopes – How Made-in-Japan Microscopes Took on theWorld” in conjunction with the Japan Microscope
Manufacturers’ Association (Figure 1.1) 1). This event washeld to commemorate 100 years since the formation of M &Katera, which became the cornerstone of domestic
microscope development in Japan. The event also showcased
how, in the short space of a century, Japan came to occupy aworld-leading position in optical microscopy, a field with a
420-year history.
While preparing for this exhibition, the author came to thestrong sense that creating a record of the history of optical
microscopes in Japan, with its unique track record oftechnological developments, would provide an extremely
valuable source of information for future researchers fromJapan and around the world. As it happened, this coincidedwith a request from the National Museum of Nature andScience to work on a systematization survey report on optical
microscope technology. The author accepted this perfectopportunity.
An increasing number of Japanese researchers have been
recipients of the Nobel Prize in Physiology or Medicine inrecent years. While this is truly wonderful, it could never
have happened without the optical microscope. Bearing thisin mind, it is indeed very significant to systematize thistechnology at this point in time.
This paper is a survey report on optical microscopes that2

use light for imaging. Other types of microscopes outside thescope of this report include transmission electron
microscopes that use electrons (see Vol. 11 2008, A
Systematic Survey of the Technical Development ofTransmission Electron Microscopes), scanning electron
microscopes, scanning probe microscopes that operate on theinteraction between the specimen and the probe (such as
atomic force microscopes, scanning tunneling microscopes
and scanning near-field optical microscopes), X-ray
microscopes and ultrasonic microscopes. Optical
microscopes also encompass a broad range of technologies,
including optics, precision instruments, electronics, softwareand ultra-precision machining and assembly. While thistechnology systematization report should likewise encompass
all of these technologies, due to the constraints of time andauthor expertise, it focuses on the development of opticaltechnology and objective lenses in particular. In order tofamiliarize the reader with the development history of
microscopes, a chapter is provided on the fundamental
principles of optics and microscopes, with as many
photographs and figures as possible. The author trusts readers
will appreciate this.
References
1) National Museum of Nature and Science: Planned
Exhibition “A Century of Japanese Microscopes”
pamphlet, 2015

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. MarchFig. 1.1 A Century of Japanese Microscopes Exhibit Poster 1)

Systematic Survey on Optical Microscope Technology in Japan

3

2

Fundamental Principles of Optics andMicroscopes 1) 2) 3)

Understanding this report first requires an explanation of
the fundamental principles of optics and microscopes. Pleaserefer to Appendix 1 for a list of the microscope-related
international standards (ISO), Japan Industrial Standards(JIS) and Japan Microscope Manufacturers’ Association
Microscope Industrial Standards (MIS) mentioned in thischapter and throughout the rest of this report.

2.1 Fundamental Principles of Optics

2.1.1
Light Wavelength and Color
Optical microscopes generally work within the range ofvisible light plus infrared light, with a longer wavelength, andultraviolet light, with a shorter wavelength. Figure 2.1 shows
the approximate color divisions of visible light. ISO 20473
defines visible light as being within the wavelength range of
380-780nm. ISO 7944 (JISB 7090) defines the reference
wavelength of various optical instruments as the mercury eline (546.07nm: green), although the helium d-line(587.56nm: yellow) is also recognized for some ophthalmic
instruments. This standard also defines the recommended
spectral lines for each color (Fraunhofer lines). Light travels
in a straight line in a homogenous medium. When it reflects
off the surface of another medium, the angle of reflection isequal to the angle of incidence. If the surface refracts thelight, the ratio between the sine of the angle of incidence andthe sine of the angle of reflection is constant (Figure 2.2).
Supposing that medium 1 shown in the diagram were air (orstrictly, a vacuum), the value is referred to as the refractive
index of medium 2. The refractive index changes with thewavelength of light. This is referred to as dispersion.
Dispersion varies according to the properties of the opticalglass. Optical glass is often defined by its Abbe number, theindicator of the refractive index and dispersion of the material(Figure 2.3).

Violet

Blue

Green

Yellow Orange

Red

Incidentlight

Reflected
light

Refractive
index n1(air: n=1)

Refractive index n2(water: n=1.33)(glass: n=1.5-2)

Optical technology comprises geometrical optics, which
utilizes the straight-line, reflective and refractive properties oflight, and physical optics, which treats light as a wave (light isa type of electromagnetic wave, the same as radio waves and
X-rays). The fundamentals of these are explained below.

Ultraviolet

number). Glass with a higher Abbe number (lower
dispersion) is known as crown glass, while glass with a lower
Abbe number (higher dispersion) is known as flint glass.

Snell’s law:

Refracted
lightSin𝜃𝜃1Sin𝜃𝜃2=

𝑛𝑛2
𝑛𝑛1

Fig. 2.2 Laws of Reflection and Refraction

White light
Prism
Abbe number 𝑣𝑣e =𝑛𝑛e −1𝑛𝑛F′ −𝑛𝑛C′

Note: Higher Abbe number= lower dispersion

Fig. 2.3 Light Dispersion and Abbe Number

The ratio of dispersion of a third wavelength, e.g. violet (gline), in relation to the dispersion of blue (F-line) and red (Cline) is referred to as the relative partial dispersion. This isrepresented by the formula θg,F = (ng - nF)/(nF - nC). Figure
2.5 shows the partial dispersion ratios of optical glass
produced by Ohara. Regular optical glass follows the
diagonal line in the figure quite closely, while anomalous
dispersion glass deviates from the diagonal line. Where thisglass is used, it is possible to design for an apochromatic lens
(apochromat) instead of a normal achromatic lens (achromat).
Special low dispersion glass with an Abbe number over 80 is
known as extra-low dispersion (ED) glass. This glass works
well for convex lenses.

InfraredFraunhofer line designations
Wavelength nm(light source)

Fig. 2.1 Approximate Classification of Visible Light and
Fraunhofer Lines

Figure 2.4 maps out the optical glass produced by Ohara,
Japan’s leading optical glass manufacturer (vertical axis
shows the refractive index, horizontal axis shows the Abbe

4

Fig. 2.4 Optical Glass Summary Chart 4)

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. MarchFig. 2.6 Explanatory Diagram of Spherical Aberration(created from cited reference 4)

2.1.2
Lens Aberration
Lens aberration refers to a geometric optical deviationfrom the ideal image formed in an optical system. This is
typically either chromatic aberration, caused by dispersion, or
one of the five constituent aberrations published in 1855 byGerman mathematician P. L. Seidel (1821-1896).
1) Spherical aberration occurs when incident light entering
an optical system from a point on the optical axis
intersects the optical axis at a different position due tothe distance from the point of incidence. For simple
convex lenses, the light farther from the optical axis
intersects closer to the image point. For simple concave
lenses, the light intersects farther from the image point.
Accordingly, correcting spherical aberration requires a
combination of concave and convex lenses (Figure 2.6 a,b, c). In the figure, the vertical axis shows the numericalaperture (NA) and the horizontal axis shows the point thelight intersects the optical axis.
2) Comatic aberration occurs when forming an image of an
object point at a distance from the optical axis. The sizeof the image distorts and blurs into a comet-like shapedue to the position of the incident light entering the lens(Figure 2.7).
3) Astigmatism occurs when an off-axis image point
produced by light rays from the off-axis image point in
the optical system does not focus. The meridional image
point (the image formed on the plane containing theprincipal ray and the optical axis) and the sagittal image
point (the image formed on the plane perpendicular to
the meridional plane and containing the principal ray) do
not correspond (Figure 2.8). The image forms straightlines at the two image points and a blurry elliptical shapeat other points.
4) Curvature of field occurs when the image surface of aplanar object curves (Figure 2.9). With this aberration,
the outer edges do not focus even though the center
focuses properly. Generally, in convex lens systems, thefurther the image surface is from the optical axis, thecloser it curves towards the lens.
5) Distortion occurs when magnification varies with thesize of the image. Distortion with increased
magnification is called positive distortion (also calledpincushion distortion), while distortion with decreased
magnification is called negative distortion (also calledbarrel distortion) (Figure 2.10).

abc

Convex lens spherical distortion
Concave lens spherical distortion
Correction of spherical distortion using a combination of convex andconcave lenses

Blurredimage point

Fig. 2.7 Explanatory Diagram of Convex Lens Comatic
Aberration
Sagittal image(= radial image)

Averaged image

Meridional light ray

Meridional image(= tangential image)

Sagittal light ray(circle of least
confusion)

Principal ray

Paraxial plane

Fig. 2.5 Optical Glass Relative Partial Dispersion Map

Objectpoint
Image plane

Lens

Meridional image plane
Sagittal image plane
Averaged image plane

Fig. 2.8 Explanatory Diagram of Astigmatism

Fig. 2.9 Explanatory Diagram of Curvature of Field

ObjectPositive distortion(pincushion)

Negative distortion(barrel)Fig. 2.10 Explanatory Diagram of Distortion

Systematic Survey on Optical Microscope Technology in Japan56) Chromatic aberration occurs when the image position
and magnification of an image is formed in an opticalsystem vary depending on the light wavelength. The
former is referred to as axial or longitudinal chromaticaberration, while the latter is referred to as transverse orlateral chromatic aberration (Figure 2.11). Where
aberration occurs due to optical glass dispersion,
chromatic aberration can be rectified with a combinationof optical glass with different properties (using low
dispersion crown glass for convex lenses and using highdispersion flint glass for concave lenses) (Figure 2.12). If
achromatism occurs for two colors, e.g. blue (F-line) andred (C-line), achromatism for a third color, e.g. violet (gline), will remain unrectified. This residual chromaticaberration is called the secondary spectrum. It is rectified
using anomalous dispersion glass, mentioned above.

surfaces with different radii of curvature (one surface inthe figure is a planar surface). The overlapping reflected
light from the two surfaces in contact causes multiple
interference fringes. In the lens manufacturing process,the processing quality is often evaluated by overlaying
the curved surface of a manufactured lens onto a
prototype with guaranteed standard curvature andsurface accuracy and assessing the number and shape of
the Newton’s rings.

Peaks and valleys
coincideLightquantity ≈ 0

Coating
Illuminatedlight

Plano-convex
lens

Glass

Planar glass
Red
Green
Blue
VioletReference
image plane

Objectpoint
White light
Violet

Blue

Green

Image plane

Red

Fig. 2.11 Explanatory Diagram of Chromatic Aberrationa. Axial or longitudinal chromatic aberrationb. Transverse or lateral chromatic aberration

Numerical
aperture
e-lineC-lineF-lineg-lineObject point
Crown glass(high νe)

Optical axis

Fig. 2.12 Correction of Chromatic Aberration
The right shows spherical aberration after chromatic correction

2.1.3
Interference, Diffraction and Polarized Light
Since light has the properties of a wave, it is subject tophenomena such as interference, diffraction and polarized
light.
(1) Light interference occurs when two or more light waves
overlap at the same point and either strengthen or
weaken each other. This phenomenon was discovered in
1803 by British scientist T. Young (1773-1829). His
experiments confirmed that shining light onto a screen
through two parallel slits would produce interference
fringes. This provided a significant basis for the lightwave theory that was under dispute at the time. Figure
2.13 shows applied examples of light interference. a)shows that when glass is coated with a thin layer of antireflection coating, interference causes a reflected lightstrength of 0 when the peaks and valleys of the lightreflected off the surface coincide with those of the lightreflected off the glass (the uncoated glass has a reflected
light strength of 4-7%). b) shows what is called
Newton’s rings, concentric interference fringes thatappear around the point of contact between two spherical

6a) Anti-reflection coatingb) Newton’s rings

White light
Off-axis object point

Flint glass(low νe)Fig. 2.13 Example Applications of Interference(2) Light diffraction occurs when light hits an object and,instead of travelling in a straight line, spreads out andeven travels into the shadow area of the object. Thisphenomenon was discovered in 1665 by Italian physicist
F. Grimaldi (1618-1663). Later scientists also carried out
various studies on diffraction, including French physicist
A. Fresnel (1788-1827), German physicist J. vonFraunhofer (1787-1826) and British astronomer G. Airy
(1801-1892). Figure 2.14 a) illustrates this phenomenon.
Because of diffraction, when light is concentrated
through a circular aperture such as a lens, even without
aberration the light will not form into a point, but spreadout as shown in b). The bright circle at the center of thediffraction pattern is called the Airy disc. The diameterof this disc is given as 1.22λ/NA (where λ is the lightwavelength and NA is the numerical aperture of the lens.
See 2.5).

Micro aperture

Fig. 2.14 Diffraction Phenomenona) Spread of light due to diffractionb) Diffraction pattern and intensity distribution from circular aperture(3) Polarized light is light with a regular wavelength(electric vector) oscillation direction. Light without
polarized light characteristics is called natural light(Figure 2.15). This phenomenon was discovered in 1808
by French physicist E. Malus (1775-1812), while using
calcite, a birefringent substance, to observe light

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. Marchreflected from a window. Birefringence is a phenomenon
in which incident light on a crystal or other substancedisperses into ordinary rays that follow the law ofrefraction and extraordinary rays that do not (Figure2.16). In 1828, Scottish geologist W. Nicol (1770-1851)
pasted together two calcite prisms to form the Nicol
prism (Figure 2.17). This and other polarized lightapparatus he devised enabled him to turn natural light,
which has a random oscillation direction, into linearlypolarized light with a regular oscillation direction. The
light could be cut by arranging a polarized lightapparatus orthogonally to the linearly polarized lightfrom another polarized light apparatus (this is referred toas crossed nicols). The original device is referred to as
the polarizer, while the other device is referred to as theanalyzer. If a crystal or other substance with opticalproperties that differ according to direction (anisotropic
material) is placed between the two devices, the light inthat area can be observed through the analyzer. The
Nicol prism used in the device was large, expensive anddifficult to use. In 1929, American inventor andphysicist E. Land (1909-1991) invented a thin polarizing
plate, which he named “polaroid”. Various
improvements followed, resulting in an inexpensive andhighly efficient polarizing element, used in sunglasses,
photographic filters and polarized light microscopes.
When there is an anisotropic material between the
crossed nicols, retardation occurs between the two rays
due to the thickness of the material and the difference inrefractive index between ordinary and extraordinary
rays. The two rays interfere with each other after passing
through the analyzer. The intensity of the interference
varies with wavelength and causes changes in color,referred to as interference color. Figure 2.18 shows aninterference color chart, showing the relationshipbetween the amount of retardation and the interferencecolor. At a retardation of around 530nm, green is cut out
altogether and slight changes in retardation can cause
yellow and red to change rapidly to blue. This is called
sensitive color.
Polarizing plate

Natural light(unpolarized)

Linearlypolarized light
Oscillation
direction

Fig. 2.16 Birefringence through Calcite 5)

Optic axis

O: Ordinary ray

E: Extraordinary ray

Fig. 2.17 Nicol Prism

Retardation

Fig. 2.18 Interference Color Chart

2.2 Images by Lens
There are two main ways to use a lens to produce animage. One method creates a real image on film or image
sensor, such as in camera photography. The other method
creates a virtual image, such as with a magnifier (or lupe).
Figure 2.19 shows a real image being created using a convex
lens.
a)

Reduced image
Convex lens

Back focal point
Real
image

Front focal point

Fig. 2.15 Polarized Light

Objectb)

Enlarged
image

Convex lens

Back focal point

Front focal point
ObjectReal
image

Fig. 2.19 Convex Lens and Real Image 1)a) Reduced image b) Enlarged image

Systematic Survey on Optical Microscope Technology in Japan7a) shows that when the object is far away from the front focal
point F, a small inverted image is produced. b) shows thatwhen the object is slightly closer to front focal point F, alarger inverted image is produced. The following formula
gives the relationship between the distance from the lens to
the object a, the distance to the image b, the lens focal length
f and the image magnification M.

By contrast, Figure 2.20 shows a virtual image being
created using a convex lens. While moving the object slightly
closer to the front focal point of the lens does not produce animage, placing the eye further back behind the lens reveals anenlarged positive virtual image. In this case, the size of thevirtual image varies according to the positional relationshipbetween the object and the front focal point of the lens. The
magnifier display magnification ML refers to the scale ofmagnification of the virtual image compared to the object
when the lens is positioned 250mm from the eye (thereference viewing distance). If the focal length of the lens is f,then ML is given as follows.
For some simple microscopes such as Leeuwenhoek
microscopes (Figure 3.3), f is reduced by 1mm. While thisallows higher magnification, observation becomes moredifficult as the distance between the eye and the lens is too
short.

Front focal point
ObjectReference viewing
distance

Fig. 2.20 Convex Lens and Virtual Image 1)

2.3 Enlarging Images by Microscope
Ordinary optical microscopes (compound microscopes)
have a system of two convex lenses. One lens is the objective
lens, close to the specimen, and the other is the eyepiece orocular lens, close to the eye. When an object AB is placed
just outside the forward focal point Fo of the objective lens,as shown in Figure 2.21, an inverted real image A′B′ (theprimary image) is formed, enlarged by the objective lens.
When this image is brought just within forward focal point Feof the eyepiece (by adjusting the focus), a virtual image A″B″
can be seen in the reference viewing distance, enlarged from
A′B′.

8

Eye
Primary
image

Eyepiece

RetinaObjective lensObjectFig. 2.21 Fundamental Optical System of a Microscope 1)

Distance

RetinaBack focal
point

Virtual image

2.4 Mechanical Tube Length and Parfocalizing

Eye

Convex lens(magnifier)

Virtual image

The total magnification MT of the microscope is given as:
MT = objective lens magnification Mo × eyepiecemagnification Me(2.4)
The size of the observed object surface (diameter: mm) is
given as:Microscope field of view = eyepiece field number FN /objective lens magnification Mo (2.5)
Here the field number FN of the eyepiece is a value that
determines the field stop diameter (mm). It is usuallyindicated on the eyepiece.

Many microscopes have several objective lenses ofdifferent magnifications mounted in a revolving nosepiece foreasy changing of magnification. In such cases, the distancefrom the locating flange of the objective lens to the locating
flange of the eyepiece and to the specimen plate have fixedvalues to maintain focus when the objective lens is changed.
The former is called mechanical tube length, while the latteris called parfocalizing distance. Mechanical tube length iscategorized as either finite (e.g. 160mm) or infinite (Figure2.22). In infinite mechanical tube length systems, the lightfrom the objective lens travels in parallel (that is, an infinite
image distance) and the primary image is formed by a tube
lens. Even with various optical elements (such as filters,
analyzers or mirrors) inserted into or removed from thisparallel light section, the image does not offset or deteriorate(Figure 2.23). While metallurgical microscopes have a long
history of use, there has been a growing emphasis on system
scalability by combining various methods of observation
using biological microscopes as well. This has meant that
infinite mechanical tube length systems are becoming thenorm for high-end microscopes. The magnification Mo∞ of
the objective lens in an infinite mechanical tube length
system is given as:

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. MarchMo∞ = ft / fo
(2.6)
where fo is the objective lens focal length and ft is the tube
lens focal length. The tube lens focal length varies between
manufacturers (e.g. 180mm for Olympus and 200mm for
Nikon; see Table 7.1). Most major Japanese manufacturers
use a parfocalizing distance of 45mm or 60mm (ISO 9345-2,
JIS B 7132-2) and 95mm for industrial lenses. The distancefrom the apex of the objective lens to the specimen plate (orabove it if a cover glass is used) is referred to as the working
distance (WD). Generally, the higher the magnification, thesmaller the working distance, although some commerciallyavailable objective lenses are easier to work with by allowing
a longer working distance at high magnification.

performance may not be achieved due to differences inparfocalizing distance, tube lens or eyepiece. New standards,
such as M25, M27 and M32, have also begun to grow in
popularity with recent advances in performance andversatility.

Image position
not offset[Finite Corrected Optical System][Infinity-corrected Optical
System]Image position
offsetLocatingflangeEyepiece

LocatingflangePrimary
image

Tube lensMechanical tube length

Half mirror,
filter, etc.

Infinite mechanical tube
lengthTube lensWorking distanceParfocalizing
distance

LocatingflangeObjective lensFig. 2.23 Advantages of Infinite Mechanical Tube Length 1)

Objective lens

2.5 Resolving Power and Numerical ApertureSpecimen

Fig. 2.22 Finite (left) and Infinite (right) Mechanical Tube
Length 1)

Table 2.1 shows the types of screw thread for objectives
and related nosepieces. The Royal Microscopical Society(RMS) thread has long been used as the standard objective
thread. As a result, objective lenses produced by many
manufacturers can be mounted into a microscope revolving
nosepiece if they match this standard. However, it isimportant to be aware that the correct magnification or

Microscopes are devices for enlarging and observing
objects. As such, the magnification value is obviously
significant, as it indicates the performance of the device.
However, it is even more important to be able to distinguishthe details of the object. This capability is referred to as
resolving power and is represented by the minimum distancedistinguishable between two points that are infinitesimallyclose to each other. The minimum distance (resolution limit)
δ is given as:
δ = kλ/NA(2.7)

Table 2.1 Types of Screw Thread for Objectives and Related Nosepieces
Nominaldiameter
20.32 mm0.706 mm

W26

26 mm

0.706 mm

M25

25 mm

0.75 mm

M27

27 mm

0.75 mm

M32

32 mm

0.75 mm

Name of Thread
Whitworth screw

Metric screw

RMS

Pitch

Comments
General use
Industrial use, reflected-light, dark-fieldmicroscopy
General use
General use, reflected-light, dark-fieldmicroscopy
Reflected-light, dark-field microscopy(from ISO 8038 and JIS B 7141)

Systematic Survey on Optical Microscope Technology in Japan

9

Here k is a coefficient that varies according to conditions,although a value of 0.61 or 0.5 is commonly used (Abbederived this formula with a value of k = 0.5). λ is the lightwavelength, usually 0.55μm for normal visible light (thewavelength of green light, to which the eye is most sensitive).
NA is the numerical aperture, the most significant value indetermining objective lens performance. It is given as:
NA = n sinθ(2.8)
Here n is the refractive index of the medium of the space on
the object side and θ is the outermost angle of light entering
the objective lens from a point on the axis, called the aperture
angle (Figure 2.24). This formula shows that the higher thenumerical aperture of the objective lens, the higher the
resolving power (low δ value). For a dry objective lens, since
the medium is air with a value of n = 1, NA does not go above
a value of 1. In fact, it has a maximum value of 0.95 (θ =72°). For an objective lens immersed in a liquid medium
between the objective lens and the specimen (cover glass),
the most commonly used homogenous immersion oil (oilwith a refractive index approximately the same as theobjective lens and the cover glass) has a value of n = 1.52,
making the maximum value of NA around 1.45. For water
immersion, the maximum value of NA is around 1.25, since
water has a value of n = 1.33. Where observation is carriedout under visible light using an oil-immersed objective lenswith a numerical aperture of 1.45, formula 2.7 gives theresolving power as δ = 0.19μm (assuming k = 0.5). This is
the minimum resolving power of an ordinary optical
microscope. However, as mentioned above, this is the twopoint resolution value. In terms of the existence andmovement of microscopic objects, it is possible to detectobjects with far smaller values than this (see 5.2 and 5.7).
There are objective lenses coming into commercial
production, used for examining high-integration LSI circuits,that use far-ultraviolet light (with a wavelength around halfthat of visible light) to significantly increase the resolving
power (see 7.4.5 (7)). Since resolving power has no direct
relationship to magnification, microstructures beyond theresolving power cannot be distinguished by increasing themagnification alone. The appropriate magnification isdetermined by the numerical aperture of the objective lens.
For observation, the total magnification falls between 500 NA
and 1000 NA. Enlarging beyond this upper limit is known as
empty magnification.

When a specimen is viewed through a microscope, there isa fixed range of focus in the direction of the thickness of thespecimen. This is called the depth of focus in object space(DOF), typified by the following formula (the Berek formula)6) 7).

n: refractive index of the medium between the specimen
and the objective lens
M: total magnification
ω: resolving power of the eye (2 minutes = 0.00058)
The first part of this formula is the depth determined fromthe resolving power, while the second part is the depth
determined from the resolving power of the eye of theobserver, which varies between individuals. The microscope
image brightness I is determined by the brightness of the lightsource as well as the numerical aperture and total
magnification.
I = IO × (NA / MT)2
(2.10)
I: image brightness IO: specimen surface brightness
MT: total magnification

2.6 Microscope Optical System Structure
The microscope optical system is fundamentally made upof the imaging system (objective lens, tube lens, etc.), theobserving/recording system (eyepiece, projection lens, etc.)
and the illumination system (collector lens, condenser lens,etc.). Figure 2.25 shows a ray diagram of a typical optical
microscope (upright biological microscope).
Primary image
Photograph/TV photo tube

EyepiecePrimary image
Viewing tube
Arm

Tube lensRevolving nosepiece
Objective lensStage

Specimen
Condenser lensAperture stop
Stand

Focusing
deviceObjective lensCollector lensLight
sourceFilterField stop

Air

Oil

Fig. 2.25 Upright Biological Microscope Ray Diagram 1)(Olympus BX50: Fig. 4.47) 1)

Cover glass
Specimen
Liquid immersion system

Slide glass
Dry system

Fig. 2.24 Explanatory Diagram of Numerical Aperture 1)

10

2.6.1
Objective Lens
As mentioned previously, the objective lens plays the mostimportant role in determining microscope performance.
Major microscope manufacturers have hundreds of types ofobjective lenses in their catalogs, categorized by
performance, use and magnification. Performance is usuallycategorized by correction of aberration (difference from the

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. Marchideal image created by the lens).
1) Achromat: correction of chromatic aberration on two
wavelengths (e.g. red and blue)2) Apochromat: correction of chromatic aberration on three
wavelengths (e.g. red, blue and green)
3) Semi-apochromat (fluorite): correction of mid-level
between achromat and apochromat
4) Plan: correction of curvature of field and astigmatism toallow focusing on the center and peripheral edge of fieldat the same time
Accordingly, the most basic objective lens is an achromat
and the highest quality objective lens is a plan apochromat.
The respective lens structures and their differences, etc. are
discussed in 7.4 with many examples.
Categorization by use includes biological and industrial(metallurgical). Biological microscopes are designed toinclude the thickness of the cover glass (usually 0.17mm, or
around 1mm for cultures). Industrial microscopes are notdesigned to include the cover glass (thickness 0mm).
Nevertheless, there are some biological objective lenses thatare designed to have no cover (such as for blood smear
preparations) and some industrial objective lenses that aredesigned to be used with a cover glass (such as for examining
LCD panels). Where mechanical tube length is finite,industrial objective lenses are less compatible than biologicallenses, as the mechanical tube length is lengthened by theamount the reflected light illumination system is placed in the
optical imaging path. This issue can be resolved by
combining the two in an infinity-corrected optical system.
There are some specialized objective lenses categorized bymethod of observation (see Chapters 5 and 6). These include
phase contrast objective lenses used in phase plates, objective
lenses for differential interference contrast / polarized lightwith optical strain removed and epifluorescent objective
lenses made of glass with high transmittance in the nearultraviolet region and little autofluorescence. As theseobservation methods have begun to be used more frequently
in combination, there has been a demand for an objective lensseries that is compatible with all methods of observation. It is
no easy task to develop a so-called universal objective lensthat will meet all of these design constraints and demonstratesuperior performance in all of these observation methods.
Nevertheless, the major manufacturers are beginning toachieve this through advances in design and manufacturing
technology, development of new types of optical glass andimprovements in coating technology.
There are other types of objective lenses on the market
with the following functions.
1) Objective lens with correction collar: When using a dry
objective lens at very high magnification and highaperture to observe a specimen with a cover glass inplace, lens performance can deteriorate if the thicknessof the cover glass differs from the design value. This lenshas a structure in place to correct any movement of theinternal lens in the optic axis direction by means of acorrection collar.

2) Objective lens with aperture stop: When using a highnumerical aperture immersed lens for dark fieldobservation, the dark field illumination can deteriorate
the contrast in the objective lens. This lens incorporates
an aperture stop mechanism within the objective lens.
3) Reflected-light, dark-field objective lens: An objective
lens for dark field microscopy with industrial
microscopes. The lens has an optical path around its
periphery for reflected light, as well as a structure on thespecimen side to illuminate the specimen against a dark
field using mirrors or lenses (see 6.4.1 and Figure 6.38).
4) Long working distance objective lens: Objective lenses
usually have a shorter working distance the higher themagnification and numerical aperture. This lens isdesigned to significantly increase the working distance,
for use in industrial microscopes and culture
microscopes.
5) Infrared objective lens: With high transmittance andimaging performance in the near-infrared region withwavelengths of 780-2000nm, this lens displays images
using an infrared camera. This is useful for inspecting
semiconductors and repairing lasers.
6) Ultraviolet objective lens: With high transmittance andimaging performance in the near-ultraviolet region withwavelengths of 240-380nm, this lens displays images
using an ultraviolet camera.
Objective lens magnification is configured based on ISO
and JIS designated values (ISO 8039, JIS B 7254). Whilemagnification ranges from very low magnification (1×, 2.5×,
etc.) to ultra-high magnification (150×, 250×, etc.),
combinations of 4× (5×), 10×, 20×, 40× (50×), 60× and 100×are normal. There are also lenses with magnifications of 16×,
32×, 63×, etc. These are based on a series of R10 preferrednumbers (10th root of 10: ISO 3). What is labelled on an
objective lens is prescribed by ISO 8578 and JIS B 7252 andincludes manufacturer name, type, magnification, numericalaperture, use, mechanical tube length, cover glass thickness
and objective field number. Lenses are also colored toindicate magnification and immersion liquid. These aresummarized in Figure 2.26 and Tables 2.2 and 2.3.

Manufacturer

Magnification

Type

Cover glass
thickness

Numerical
Magnification
aperture
Use (differential interference
contrast)
Combination prism

Mechanicaltube length
Magnification
color ringWorking distanceCorrection collar
Cover glass
thickness scale

Numerical aperture
Immersion liquid

Use (phase contrast)
Phase ring / typeMechanical tube length
Cover glass thickness

Working distanceObjective field
numberMagnification color ring
Immersion color ring

Cover glass

Immersion liquid(immersion oil)

Slide glass

Main display codes: POL (P, PO) for polarization, EPI (M) for reflected illumination, UV for
fluorescence/ultraviolet, IR for infrared, NCG for no cover glass, L (LWD) for long working
distance
Display colors: Red for polarization, green for phase contrast

Fig. 2.26 Example Objective Lens Label 1)

Systematic Survey on Optical Microscope Technology in Japan11

Table 2.2 Ring Color Classification for Objective Lens Magnification
Magnificationvalue

1/1.25

Ring Color

black

1.6/2

2.5/3.2

gray

brown

4/5

6.3/8

red

orange10/12.5

16/20

25/32

40/50

60/63/80≥100

yellow

light
green

dark
green

light blue

dark blue

white

Table 2.3 Ring Color Classification for Objective Lens Immersion Medium
Medium

air

oil*

water

glycerolothersRing Color

none

black

white

orangered* Immersion oil designated in ISO 8036 and JIS K 2400

2.6.2
Tube Lens
The infinity-corrected objective lens discussed in 2.4
forms images in combination with a tube lens. Since the lightpencil running between the objective lens and the tube lens isparallel (Figure 2.22), altering the distance between thelenses will not change the position and magnification of the
primary image, although the edge of the image will start todarken beyond a certain distance. To prevent deterioration in
performance at the peripheral edge of the image, the tube lensmust adequately correct image edge aberration on its own(see Figure 2.25 and Figure 6.37).
2.6.3
Eyepiece
The eyepiece produces a further enlarged virtual image toenable the real image created by the objective (and tube lens)to be viewed by the eye. Eyepiece magnification is generally
within the 8-15× range, although some are 5×, 20× and 30×.
The field number (FN), which indicates the visible field ofview, also varies from eyepiece to eyepiece. For standard 10×magnification, a field number of 18 or higher is called widefield, while 23 or higher is called ultra (or super)-wide-field.
The outer diameter of the part of the eyepiece inserted into
the tube sleeve is a standard specified size of 23.2mm or
30mm (ISO 10937 and JIS B 7143). What is known as higheyepoint allows the position of the eye (eyepoint) to be
farther from the end face of the eyepiece during observation,such as if the observer is wearing glasses. Some eyepieces
also have a diopter adjustment mechanism to compensate forthe difference in vision between each of the observer’s eyes.
There are also some eyepieces on the market that have abuilt-in (or detachable) graticule (Figure 2.27) at the field
stop, etched with micrometers or a similar scale. Figure 2.28
shows an exterior view of an eyepiece, with each symbol
defined by standards (ISO 8578, JIS B 7252). The types of
eyepiece lenses are discussed in 7.5.

Magnification

Type
Country of
manufacture

Field number
Suitable forspectacle wearers
Manufacturer

Fig. 2.28 Example Eyepiece Markings 1)

2.6.4
Photographic Projection Lens
This lens projects the real image from the objective lens toa recording device such as photographic film or CCD. It is
mounted on the straight portion of a trinocular tube system.
For 35mm film photography, projection magnification isusually around 2.5-5×. With digital cameras now becoming
widespread, imaging devices are much smaller in size,
meaning projection magnification of 1× or less is now often
used. Figure 2.29 shows the relationship between field ofview and photographic film or imaging device capture range.

Fig. 2.29 Field of View and Capture Range 1)
Projection lens magnification in ( )Grid 10 mm / 10

Fig. 2.27 Examples of Various Graticules (Micrometers) 1)

12

2.6.5
Tube System
Viewing tubes can be monocular, binocular, trinocularetc., depending on the number of eyepieces and projectionlenses fitted. Monocular tubes can be straight along theoptical axis or inclined, using prisms or mirrors for a better
viewing angle (Figure 2.30a). Binocular tubes split the lightrays into two optical axes for the left and right eyepiece using
either the Jentsch system (Figure 2.30b) or the Siedentopf
system (Figure 2.30c). The former has a mechanism to

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. Marcha) Inclined monocular tubeb) Jentsch binocular tubec) Siedentopf binocular tube

Tube 3

Binocular
sectionTube 5

Image relay lens

Eye

Eyepiece

Field stop

Objective lens backfocal point

Specimen

Fig. 2.31 Structure of Köhler Illumination System 1)

Image relay lensIntermediate
image

Eyepiece

Intermediate
image
Tube 2d) Tube with variable tilt

Objective lensNote) ──Solid line: light rays showing the specimen imaging relationship ----Dashed line: light rays showing the light source (filament) imaging relationship

Tilt angle (variable)
Intermediate
image

Aperture stop

Intermediate
image

Condenser lens

Eyepiece
Intermediate
image

Field stop

Eyepiece
Intermediate
image

Light source

Eyepieceof the light source at the front focal point of the condenser
lens, thus placing the light source image at an infinite
distance from the specimen, thereby preventing uneven
illumination. With Köhler illumination, the aperture stop canbe placed at the light source image position, or the field stop
can be placed at a point where it conjugates with thespecimen surface (in relationship with the object and theimage). Adjusting these produces the optimum level ofcontrast. Consequently, most high-end microscopes use
Köhler illumination.

Collector lensautomatically compensate for the forward/backward shift of
the intermediate image position caused by adjusting theinterpupillary distance. Trinocular tubes (Figure 2.25 tubearea) comprise an inclined binocular tube with an additionalstraight tube containing a photographic device or similar.
Distributing the light path between this tube and the viewing
tube is usually achieved by moving prisms. Other types oftubes available on the market include binocular systems withvariable tilt angle (Figure 2.30d) and discussion tubes thatallow observation by multiple people at the same time
(Figure 2.30e: five-person intermediate tube).

Tube 1

Tube 4e) Intermediate tube for discussion (for five people)

Fig. 2.30 Example Structures of Various Tubes 1)

2.6.6
Illumination System
Since microscopes are used for enlarging and observing
minute portions of a specimen, illumination is essential for
maintaining brightness levels. The simplest illumination
device is a reflecting mirror (Figures 4.5-14 show
microscopes of this type) that makes use of a natural lightsource, such as a north-facing window or frosted glass
window (avoiding direct sunlight), or an artificial lightsource, such as an electric lamp. The reflecting mirror often
has a flat surface on one side and a concave surface on theother side, with the flat side used for low-magnification
viewing and the concave side used for high-magnification
viewing. A condenser lens is also used to concentrate thelight onto the specimen surface.
Proper observation requires a dedicated artificial lightsource. The illumination system needs to meet certain
conditions, such as adequate brightness of white light,
uniform illumination of the entire observation range andmeeting the maximum aperture of the objective lens.
Ordinary light sources (such as tungsten lamps and halogen
lamps) have a filament structure that produces conspicuously
uneven lighting on the specimen surface when used as adirect light source. This makes them particularly unsuitable
for low-magnification viewing and photography. A. Köhler
(Figure 3.8) devised Köhler illumination, an illumination
system to resolve this issue and satisfy the conditions given
above. As shown in Figure 2.31, this system creates an image

Halogen lamps with high luminance and high color
temperature (light source chromaticity) are often used as alight source. However, color balance filters (color
temperature converters) should be used to produce
completely white light. Since color temperature varies withlamp power voltage, any changes in brightness after adjusting
the color temperature are carried out using a neutral density(ND) filter to maintain the color temperature.
2.6.7
Condenser Lens
The condenser lens is used to concentrate the illuminating
light onto the specimen surface effectively. There are various
types depending on the purpose (Figure 2.32). Regularcondensers most commonly comprise a two-lens structure
known as an Abbe condenser. However, to maximize highend objective lens performance, it is recommended to use anachromatic aplanatic condenser (AAC) that corrects forspherical aberration and chromatic aberration regardless of
the illumination system. According to optical theory, it isdifficult to satisfy both the low-magnification microscope
field of view and high-magnification numerical aperture ofillumination with one condenser lens. This has resulted inwidespread use of swing-out condensers, in which the top
lens can be shifted in and out of the optical path whenswitching between low magnification and high magnification.
There are also specialized condensers for the various methodsof observation mentioned in the following chapters (seeChapter 5: dark-field microscopy, phase contrast microscopy,
polarized light microscopy, differential interference contrast
microscopy, modulation contrast microscopy, etc.), as well asuniversal condensers that combine all of these into one.

Systematic Survey on Optical Microscope Technology in Japan

13

Lens
configuration

Name
Numerical
aperture
Objective lensmagnification

Abbe condenser

Achromatic aplanatic condenser

1.25

1.4

Swing-out condenser
0.9 (top lens in)

4x ~ 100x

10x ~ 100x

2x ~ 4x (top lens out)
10x ~ 100x (top lens in)

Fig. 2.32 Various Condenser Lens Examples 1)

2.7 Microscope Types and Structures
Microscopes can be categorized by structure as uprightmicroscopes, by which the specimen is observed from above,or inverted microscopes, by which the specimen is observed
from underneath. They can also be categorized as biologicalmicroscopes, by which light transmitted through a biological
specimen or other test piece, or industrial microscopes(metallurgical microscopes), by which light is reflected off an
opaque specimen such as metal. Other types of microscopes
include stereomicroscopes, which allow three-dimensional
observation of a specimen. The respective characteristics are
discussed below.
2.7.1
Upright Microscope
Throughout the long history of the microscope, manydifferent types have been developed with various advances inform as science has progressed in medicine, biology, industry
and other fields. The most widely used microscope today is
the upright microscope. As shown in Figure 2.25, thismicroscope has the objective above the specimen and caneither be a transmitted-light (trans-illumination) microscopeor a reflected-light (epi-illumination) microscope, dependingon the type of illumination. Upright transmitted-lightmicroscopes are most commonly used in the fields of
medicine and biology, although some research uses uprightmicroscopes that are capable of both trans and epiillumination. By contrast, upright reflected-light microscopesthat incorporate epi-illumination systems between the baseand the tube are used for inspecting industrial components
such as semiconductors and materials.
2.7.2
Inverted Microscope
Unlike the upright microscope, the inverted microscope isdesigned so that the specimen is observed from underneath(see 6.1 and 6.4). The objective lens is underneath the stage.
To allow observation in the same manner as for uprightmicroscopes, the optical axis bends diagonally upwards to theeyepiece. Since this lengthens the optical path, an opticalsystem is sometimes used to relay the primary image fromthe objective lens to the eyepiece. Inverted microscopes arealso categorized by illumination method as transmitted lightor reflected-light. Transmitted-light inverted microscopes areoften used in the fields of medicine and biology, mainly for
examining culture cells. Simple versions of these are known

14

as culture microscopes. As these need to allow observation of
the culture vessel (Petri dish) from underneath, they
incorporate a trans-illumination system mounted above thestage and a condenser with a long working distance. The
culture microscope’s objective lens also has a long working
distance, as it is designed to accommodate the dish being
much thicker than an ordinary cover glass. The stage isstationary, while the objective lens moves up and down tofocus. This is essential for performing tasks such as
micromanipulator cell manipulation. Inverted biologicalmicroscopes are useful for observing living specimens andhave become very widely used in recent cutting-edge bio
research. In industrial fields, inverted microscopes are mainly
used for studying and examining metal materials. Simply
putting a polished metal surface face down on the stage canlevel the observation surface, while the stationary stage cantake even large and heavy specimens.
2.7.3
Stereomicroscope
Observing a specimen three-dimensionally requires
parallax between the left and right eyes. A stereomicroscopeis a low-magnification, wide-field, long working distancemicroscope that uses two optical paths to create a threedimensional image to observe a specimen from different
directions (see 6.2). The observed image is turned upright byan erecting prism inside the tube. These microscopes aremainly used for assembly and inspection in the precision andelectronics industries and for dissection and cell manipulationin the fields of medicine and biology. The surgicalmicroscopes used in brain surgery and ophthalmology arealso stereomicroscopes.
There are two types of stereomicroscopes: convergent
microscopes (Figure 2.33a, also called Greenoughmicroscopes), which have two optical systems, left and right,
and two optical axes at a fixed convergence angle (around12°), and parallel microscopes (Figure 2.33b, also called
common main objective (CMO) microscopes), which have
two optical systems, left and right, and two parallel opticalaxes from one objective lens. The former is widely used due
to its compact structure and ease of operation. The latter has
the advantage of being easily lengthened and has been widelyadopted as a high-end microscope. Magnification is usuallychanged by zoom, although it can also be done by changing
objective lenses and conversion lenses. While these have a

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. Marchlower resolving power than ordinary microscopes due to asmaller numerical aperture at the same magnification, they
have a high depth of focus and tend to be used in types ofwork relevant to this. Stereomicroscopes often have simple
illumination systems using fluorescent lamps or light guides,
although high-end stereomicroscopes may have transillumination devices, dark field illumination devices or
coaxial epi-illumination devices.
Right eyeRight eyeLeft eyeEyepiece

Left eyeEyepiecePrimary image

Primary image
Erecting prism

The various mechanical components of a microscope are
discussed below.
(1) StandThe stand is the main body of the microscope and is madeup of the base underneath, which supports the whole stand,and the arm, which supports the optical system. The shape,size and weight of the base maintain the stability of the entire
microscope. Many smaller microscopes have a U-shapedbase, although newer microscopes with built-in illumination
systems often have a rectangular, T-shaped or Y-shaped base.
The arm is very solid, as it supports the stage and has the tube
and camera device, etc. at the top. The focusing is also built
into the arm.

Erecting prism(2) Stage
This component holds the specimen and allows smooth
and accurate movement. The stage is either stationary,attached to the base, or moveable, moving up and down withfocusing. Types of stage include the plain stage (Figure
2.35a), in which the specimen is held by two clips and moved
by hand, and the mechanical stage (Figure 2.35b), in which
the specimen is moved in four directions using knobs. Thereis also a 360° rotating stage (Figure 2.35c), used for polarized
light microscopy and similar, and a large stage (Figure
2.35d), for examining large wafers or liquid crystal panels inindustrial applications.

Tube lensObjective lens(zoom)

Convergenceangle

Objective lensConvergence angle

Specimena) Convergent type

Convergenceangle

Specimenb) Parallel typeFig. 2.33 Stereomicroscope Optical System 1)

2.8 Microscope Components
Microscopes are made up of the objective lens andeyepiece for enlarging and viewing specimens, the lightsource for illuminating the specimen, the condenser lens andother parts of the optical system, as well as the mechanicalsystem that supports these. Figure 2.34 lists the different partsof an upright biological microscope.

(3) Focusing
This component is for adjusting the focus on a specimen. It
has a coarse focus knob for observation at low magnification
and a fine focus knob for high magnification. In high-end
microscopes, these are coaxial (Figure 2.36).

Photographic device
clamp screw

Photographic tube
adaptor
Trinocular tube

Optical path switching lever

Diopteradjustment ring

Tube clamp screw

Objective lensRevolving nosepiece
clamp screw

Substage clamp screw
Condenser clamp screw
Coarse focus stopper
clamp ring

Revolving
nosepiece
Objective lensSpecimen holder

Stage left-right motion knob
Brightness adjustment dial

Filter release lever
Condenser aperture stopring

Fine focus knob
Stage front-back motion knob

Condenser verticalmotion screw

Condenser scale

Stage
Stage rotation
clamp screw

Pilot lamp
Condenser centering screw
Field stop ring

Power switch
Fine focus knob
Coarse focus knob

Auto photo switch
Auto photo voltage selection
switchFilter insertion lever

Condenser

Coarse torqueadjustment ring

Field lens

Diffuser insertion/removal screw

Fig. 2.34 List of Various Microscope Parts (Nikon E600: Fig. 4.50) 8)

Systematic Survey on Optical Microscope Technology in Japan15

Fig. 2.35 Examples of Various Stages 9)a) Plain stageb) Mechanical stagec) Rotating staged) Large stage

2.9 Microscope Accessories
There are all kinds of accessories for high-end
microscopes. These form part of the microscope system toachieve various purposes, such as observing, recording andmeasuring. The following is a brief introduction to sometypical accessories.

Fig. 2.36 Coaxial Focusing System 9)(4) TubeThis component is built into the upper section of the armand has the eyepiece at the top and the revolving nosepieceand objective lens at the bottom. In older microscopes, thetube moves up and down on a rack and pinion system
together with the objective lens and eyepiece while focusing.
In many newer microscopes, the tube is stationary andclamped to the arm (it can be rotated). Details are omitted
here, as the types of tube are discussed in 2.6.5.
(5) Revolving NosepieceThis component rotates objective lenses of different types
and magnification. It can hold 2-7 objective lenses (Figure2.37). It is machined very precisely to allow the objective
lenses to be switched quickly and smoothly, with as little
impact as possible on the focus or position of the specimen in
the field of view.

2.9.1
Photographic Devices
The importance of photography for recording microscope
images goes without saying. Microscope cameras once usedsilver halide film and required various filming techniques andexpertise to operate. As electronics technology developed,
manufacturers improved photomicrographic devices andautomated the following tasks. Figure 2.38 shows examples
of automatic photographic devices.
1) Loading, winding and rewinding film
2) Setting film properties (= DX code reading)3) Adjusting color temperature (= setting power voltage)
4) Switching illumination systems (adjusting field stop andaperture stop)
5) Focusing (autofocus)
6) Photometry (moving spot photometry, two-dimensional
photometry)
7) Exposure (reciprocity law failure correction, auto
bracketing)
It is also possible to mount multiple cameras, withfunctions including zoom magnification with easy framing
and overlaying of scale data. These improvements have madephotomicrography relatively easy, with the photographer only
needing to choose the position of the specimen and themagnification of the photograph. However, with digital
image recording now widespread, even these devices are
falling out of use.

Fig. 2.37 Revolving Nosepiece (7 positions) 9)

Fig. 2.38 Automatic Exposure Device 9)16National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. March

2.9.2

CamerasMicrophotometric section, and a photometric tube (orRecording the dynamic behavior of specimens was once

photometric finder) (Figure 2.40). There are also high-speed

done by filming with 16mm cine devices. This was difficult

excitation switching units and dichroic mirror units forand prone to failure and met its end with the appearance ofmeasuring Ca2+ concentrations. Other devices can bevideo. Video devices grew rapidly in popularity for recording

combined with monochromators for spectral photometry, or

microscope images, as they were not only easy to use, butwith auto scanning units for two-dimensional distribution

also offered technological advances in image quality andphotometry. A computer carries out various statisticalsensitivity. Cameras, particularly 3-CCD color video

processing, image processing and time-dependent analysis ofcameras, Hi-Vision HDTV cameras and high pixel digitalthe measurement data and displays it on a monitor.

cameras, have become an essential unit in the system, due tothe ease of analyzing, processing and saving microscope
images on computer.
2.9.3

Measuring Systems

When measuring specimen tissues and cells, it is easy totake larger measurements with the XY stage scale, but moredetailed measuring requires an eyepiece with a graticule(Figure 2.27). For even greater accuracy, there are also
micrometer eyepieces (Figure 2.39). Since there can bemeasurement errors such as magnification errors or lensdistortion depending on the objective lens used, they need to
be precisely calibrated with an objective micrometer.
Measuring microscopes have many accessories formeasuring, although details are omitted here.

Fig. 2.40 Microscope photometer 9)

References
1) Nagano C.: Kōgaku wo Chūshin to shita Kenbikyō no
Kiso [Microscope Fundamentals with a Focus on
Optics], Japan Microscope Manufacturers’ Association
website http://www.microscope.jp/knowledge/index.
html (2016.12.20), supplied by Japan Microscope
Manufacturers’ Association
2) Nagano C.: New Optical Technology Handbook, IV
Optical Equipment, 1.2 Optical Microscopes, Asakura
Publishing Co., Ltd., pp. 685-704, 2002
3) Nagano C.: Kōgakukenbikyō no Kiso to Ōyō[Foundations and Applications of Optical Microscopes],
The Japanese Journal of Medical Photography, Vol. 34
No. 2 – Vol. 35 No. 1, 1996-19974) Uehara S.: Kōgaku Garasu no Kō Kussetsu-Ritsu-ka[High Refractive Index Optical Glass], Japanese Journal

Fig. 2.39 Micrometer Eyepiece 9)of Optics, Vol. 42 No. 7, pp.345-350, 2013
5) Basic manual for polarized light microscopes, Olympus

2.9.4

Microscope photometers

Microphotometry measures the fluorescence andtransmittance of cells and is used for photometric analysis of2+ and other ion

DNA/RNA/protein quantities or Caconcentrations. Microscope photometers were once large,
specialized devices, but now come in the form of modules
that can be mounted onto ordinary microscopes. They are
made up of a high sensitivity photomultiplier and controller,a photometric unit with multiple pinholes to limit the

Optical Co., Ltd., 1995
6) Martin L.C.: The Theory of the Microscope, Blackie
London, pp.192-205, 1966
7) Tsuruta T.: Mokushi Kōgaku Kikai no Butsukūkan
Shindo [Object Space Depth of Visual Optical
Instruments], 5. Light Pencils, New Technology
Communications, 1997, pp.365-379
8) Nikon: Biological microscope E600 instruction manual9) Supplied by Olympus Corporation

Systematic Survey on Optical Microscope Technology in Japan17

3

Invention and Development of Microscopes 1) 2)
3) 4) 5)

3.1 Optics and Lenses
Various phenomena of light have caught the interest ofphilosophers since ancient times. The law of reflection,
which forms the basis of geometric optics, was noted byGreek mathematicians Euclid (330?-275? BCE) andthe following year, opening the door to modern science, as iswell known. In 1611, German astronomer Johannes Kepler(1571-1630) published his work “Dioptrice” theorizing on
telescopes in which the objective lens and eyepiece are bothconvex lenses.

Archimedes (287?-212 BCE) in the third century BCE. The
law of refraction was noted by Ptolemy of Alexandria in thesecond century CE, although the correct refraction
relationship formula was not discovered until the 15th
Eyepiece

century, by Dutch astronomer W. Snellius (Snell). The later

Objective lensdecline of Greece and growth of Christianity spread scienceFig. 3.1 Janssen Microscope Configuration

to Arabia. Ibn al-Haytham (Latin name Alhazen, 965-1040)(created from cited reference 4)

made a detailed record of the reflection and refraction of lightrays in his “Book of Optics”, published in the early 11th
century. He also made reference to magnification by convex
lenses and other phenomena. The work was translated into
Latin and had a significant impact on later developments inth century, British friar Roger Bacon (1214-

optics. In the 131294) wrote about magnification by lenses and suggested theutility of this in reading glasses. The first pair of reading
glasses was made in Venice, Italy in the 1280s. Glasses grewsteadily in use by monks studying the Bible. The earliest
record of glasses and magnifying glasses is a fresco (1352) ina church in northern Italy, which depicts a cardinal wearing
glasses reading a book and a monk using a magnifier to read.
The first glasses using concave lenses for nearsightedness
appeared in the early 15th century. Groups of spectaclemakers began to emerge all across Europe.

3.2 Invention of the Microscope and Telescope

Robert Hooke (1635-1703) of the Royal Society of
London made a microscope of his own, comprising an
objective lens and an eyepiece (both convex lenses). He
published his biological observations in “Micrographia” 6) in
1665. His detailed engravings of a flea, a fly, a louse andother creatures were very popular, and the work became abest seller. Hooke named the cavities in cork “cells” (Figure3.2). Antonie van Leeuwenhoek (1632-1723), a draper from
Delft in the Dutch Republic, made a large number of his own
single-lens microscopes (Figure 3.3). His discoveries in the1670s and 80s included red blood cells, microbes in water,
yeast, bacteria and sperm (Figure 3.4) 7). He reported thesefindings in detail to the Royal Society of London and later
became known as the “Father of Microbiology”.
Leeuwenhoek made improvements to his microscope by
grinding his own tiny convex lenses. He is believed to haveachieved an astonishingly high magnification of 275× with asingle lens and a resolving power of 1.4μm, although he was

A commonly held view is that the first compoundapparently the only one who could work his microscopes

microscope using a combination of two convex lenses wasproperly. A number of microscope makers emerged in theinvented around 1590 by Zacharias Janssen (c.1580-c.1638),

later 17th century through to the 18th century, includinga Dutch spectacle-maker from Middleburg, with his father,

Giuseppe Campani in Italy, John Marshall, Edmund

Hans Janssen, although this is subject to much debate.

Culpeper, John Cuff, Benjamin Martin and George Adams

Janssen’s microscope (Figure 3.1) is purported to have

Sr. & Jr. in the United Kingdom, and Camille Sebastiencomprised a biconvex objective lens and a plano-convex

Nachet in France. However, it being 200 years before theeyepiece fitted inside a brass tube, with a total magnification

invention of achromatic objective lenses and theof around 9×. In 1608, Janssen’s neighbor, spectacle-makerestablishment of microscope resolution theory, theseHans Lipperhey (1570-1619), became the inventor of thecompound microscopes were no match for Leeuwenhoek’s

telescope with his patent of a telescope comprising a convex

single-lens microscope.

objective lens and a concave eyepiece. This device reached
Italy, where Galileo Galilei (1564-1642) used a telescope of
his own making to observe various astronomical phenomena

18

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. March

3.3 Advances in Objective Lenses
The microscope is an instrument used to enlarge
infinitesimal objects and observe their composition in detail.
The performance of the microscope is determined by theperformance of the objective lens. The first improvement to
the objective lens was removing various aberrations,especially chromatic aberration. Sir Isaac Newton (16431727), who discovered the light spectrum, is well known forusing a reflector to make a reflecting telescope (1668), with
the idea that it would never be possible to eliminate
chromatic aberration with an objective telescope lens thatrefracted light. Swiss mathematician and physicist Leonard
Fig. 3.2 Hooke’s Microscope: from Micrographiaa) Microscope illustrationc) Drawing of cork

6)b) Drawing of a flea

Euler (1707-1783) proposed in 1747 that it would be possible
to eliminate lens chromatic aberration by combing different
materials. In 1758, British optician John Dollond (17061761) achieved an achromatic lens by combining a convex
lens of low dispersion (refractive index varies with

Single lens

wavelength) crown glass with a concave lens of highSpecimenObserverdispersion flint glass. Later, achromatic lenses were also used
for microscope objective lenses, but these were more difficult

Focusingscrew

to design and produce than for telescope objective lenses. In
1830, British optician Joseph J. Lister (1786-1869)
successfully produced a practical achromatic microscope
Screw to movespecimen up and down

objective lens (Figure 7.1). He also confirmed that it wasnecessary to increase the numerical aperture of the objective
lens in order to increase resolving power. In 1837, ItalianFig. 3.3 Leeuwenhoek’s Single-Lens Microscope

astronomer Giovanni B. Amici (1786-1863) designed ana) Exterior view
(replica held by the Japan Microscope Manufacturers’ Association)b) Usage diagram

objective lens with even higher magnification by adding a(created with reference to cited reference 3)

hemispherical lens on the object side (Figure 7.2). Amici
further increased the numerical aperture by filling the space
between the object and the end lens with liquid (immersion
technique) and devised an objective lens with even greater
resolving power. These improvements to objective lenses
finally gave the compound microscope greater resolving
power than the simple microscope. The simple microscope isalso harder to use, and only survived in the form of a highmagnification lupe (20-30×) used for a dissection
microscope. From the start of the 19th century, the United
Kingdom led the world in microscope production, with
developments made by Andrew Ross, James Smith &Richard Beck, Hugh Powell & Peter Lealand, and William
Watson etc. In 1839, Lister and others founded theFig. 3.4 Leeuwenhoek’s Observational Drawings 2)a) Fish red blood cellsb) Volvoxc) Human and canine sperm

Microscopical Society of London (renamed the RoyalMicroscopical Society (RMS) in 1866 after gaining its royalcharter).

Systematic Survey on Optical Microscope Technology in Japan

19

3.4 Rise of German Microscopes 8) 9) 10) 11)
From the mid-19th century, businesses began to beestablished outside of the United Kingdom as well, some ofwhich later became global microscope manufacturers. In the
Unites States, Charles Spencer (1813-1881) founded the
Spencer Lens Company in 1847 in Buffalo, New York. (Thisbecame the American Optical Company in 1835 and then partof the Leica Group in 1990). In 1853, John J. Bausch (18301926) and Henry Lomb (1828-1908) founded Bausch &Fig. 3.5 Zeiss 12)

Fig. 3.6 Abbe 12)

Fig. 3.7 Schott 12)

Fig. 3.8 Köhler 12)

Lomb in Rochester, New York (which became part of the
Leica Group in 1990). Meanwhile, in Germany, Carl Zeiss(1816-1888, Figure 3.5) started an optical workshop in Jenain 1846, while Carl Kellner (1826-1855) did the same in
Wetzlar in 1849.
Carl Zeiss AG (referred to below as Zeiss) worked
constantly to improve its manufacturing of microscopes rightfrom the founding of the company. The young physicist Ernst
Abbe (1840-1905, Figure 3.6) was invited to work on
theoretical research and practical development of objective
lenses to make production even more scientific. As part of hiswork, Abbe published the sine condition that forms the basisof objective lens design in 1870 and a theory of microscope
imaging in 1872 (see 2.5), as well as developing various
measurement methods and devices. He achieved successive
ground-breaking results that made dramatic improvements tomicroscopes, such as the Abbe condenser (Figure 2.32) inproduction and developed as a global microscope
manufacturer on par with Zeiss. Its objective lenses, designed
by mathematician Carl Metz (1861-1941), were highly
regarded. Leitz’s son-in-law Carl Reichert (1851-1922,

1873, the homogenous oil immersion method (see 2.5) inFigure 3.10) founded a new microscope company (part of the1877 and the apochromat objective (see 2.6.1) using calcium

Leica Group since 1990) in Vienna, Austria, in 1876, which

fluoride (CaF2) in 1886. Abbe also founded a glass works ingrew into a leading European microscope manufacturer after

Jena in 1884 with Otto Schott (1851-1935, Figure 3.7), who

Zeiss and Leitz. The Leica 35mm camera, invented by Leitz

had developed new type of glasses in 1879. In 1900, Abbe

engineer Oskar Barnack (1879-1936) and developed into a

brought August Köhler (1866-1948, Figure 3.8), who hadcommercial product in 1925, dominated the camera market

published a new illumination method (Figure 2.31) in 1893,

due to the lenses by optical designer Max Berek (1886-1949,

into the company. In 1897, he developed the first

Figure 3.11). In competition, Zeiss Ikon launched the Contax

stereomicroscope (see 2.7.3), based on an idea proposed by

35mm camera in 1932, with noted rivalry ensuing between

American biologist Horatio Greenough. Abbe continued

the two companies. Since Zeiss was in located in the east of

running the company as the Carl Zeiss Foundation after

Germany, a month after Germany surrendered to the Allies inZeiss’ death. He was an outstanding industrialist as well whoestablished many modern working conditions. Köhler andAbbe’s other successors were involved in later inventions anddevelopments in microscopy, while Zeiss continues to be aworld leading company in the optical industry.
The optical company founded by Kellner was taken overby Ernst Leitz (1843-1920, Figure 3.9) in 1869, under thename Ernst Leitz GmbH (the microscope division is now
Leica Microsystems, referred to below as Leitz and from1990 onwards as Leica).

20

The company experienced significant growth in microscope

1945, US armed forces transported 126 Zeiss supervisors andengineers to the western side to recreate a West German
Zeiss company in the southern German town of Oberkochen.
This meant that after the war, Zeiss resumed its production of
optical instruments as a divided entity across East and West
Germany, although in 1991 the company reunited in
Oberkochen. Meanwhile, Leitz, based in West Germany, wasquick to get up and running again after the war, having
suffered minimal damage.

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. MarchFig. 3.9 Leitz 13)

Fig. 3.10 Reichert 13)

Fig. 3.11 Berek 13)

References
1) Wagakuni no Kenbikyō no Ayumi [History of Japanese
Microscopes], Science Museum Supporters’ Association,
19632) Kobayashi Y.: Sekai no Kenbikyō no Rekishi [History of
the World’s Microscopes], 1980
3) Tanaka S.: Kenbikyō no Rekishi [History ofMicroscopes], Kyushu Bunko, Touka Shobo, 1979
4) Hayashi H.: Shashin de Miru Kenbikyō Hattatsu no
Shiteki Tenbō [Historical Perspectives on theDevelopment of the Microscope as Seen in Photographs],
1988, p.100
5) Tsuruta T.: New Optical Technology Handbook, I.
History of Optical Technology, Asakura Publishing Co.,
Ltd., 2002
6) Hooke R.: Micrographia, Royal Society, 1665 (Dover
edition 1961)
7) Ford B.J., Ito T. (trans.): Shinguru Renzu: Tanshiki
Kenbikyō no Rekishi [orig. title Single Lens: The Storyof the Simple Microscope], Libraria, Hosei University
Press, 1986
8) Innovation - Zeiss Information with Jena Review, No.1,
Carl Zeiss, 1996
9) Innovation No.15, In Memory of Ernst Abbe, Carl Zeiss
AG, 2005
10) Carl Zeiss 150 years Innovation in Optics, Carl Zeiss
Jena GmbH, 1996.11
11) Scheffel F., Fujita G. (trans.): Garasu no Kyōi [orig. title
Gläserne Wunder], Ten-nen-sha, 1942
12) Supplied by Carl Zeiss Co., Ltd
13) Supplied by Leica Microsystems

Systematic Survey on Optical Microscope Technology in Japan21

4

Birth and Growth of Japanese Microscopes

4.1 Japanese Microscopes from the Edo Period
to the Meiji Period 1) 2) 3)
Microscopes are estimated to have been brought to Japanaround 1750. This was quite a late date compared to thetelescope, which the British presented to Tokugawa Ieyasu in
1613, not long after its invention. The first documented
mention of the microscope is in “Oranda Banashi [Dutch
Tales]” by Gotō Rishun in 1765. In 1781, Nakai Riken of
Osaka wrote “Kenbikyō-ki [Microscope Records]”, statingthat Hattori Eishaku and Aburaya Kichizaemon had mademicroscopes. Japan’s oldest existing microscope, a wooden
microscope (Figure 4.1) made by Kobayashi Kiemon thatsame year, is on display at the Shimadzu Foundation
Memorial Hall (Kyoto). In 1787, Morishima Chūryō includes
sketches of a “mikorasukobiyun” or Culpeper microscope(Figure 4.2), a mosquito, a flea and a mosquito larva in his
work “Kōmō Zatsuwa [Various Accounts of the Dutch]”. His
brother Katsuragawa Hoshū used a microscope in medicine,
and wrote “Kenbikyō Yōhō [How to Use a Microscope]” in
1802. Iinuma Yokusai published “Sōmoku Zusetu [Diagramsof Plants]” in 1832. In 1833, Udagawa Yōan, who had been
given a microscope by Philipp F. von Siebold on a visit toJapan, published “Shokugaku Keigen [Origins of Plants]”.
Doi Toshitsura, feudal lord of Koga Domain, studied snow
crystals under a microscope and published “Sekka Zusetsu[Diagrams of Snow crystals]” (Figure 4.3), which led to alater popular craze in snow crystal patterns. Thus, we see thatmicroscopes in the Edo Period were only used for interest or
for study by a few individuals of culture or scholars ofWestern knowledge.

Fig. 4.2 From “Kōmō Zatsuwa [Various Accounts of the
Dutch]”

Fig. 4.3 From “Sekka Zusetsu [Diagrams of Snow
crystals]”

Fig. 4.1 Japan’s Oldest Existing Domestically Produced
Microscope (held at Shimadzu Foundation
Memorial Hall) 4)

22

In the Meiji Period, Western civilization started flooding
into Japan. In the field of medicine, cutting-edge medical
science from Germany was adopted without delay.
Successive discoveries in the area of disease-causing
pathogens using high-powered microscopes led to rapid
developments in bacteriology and immunology in particular.
As a result, Japanese universities and government institutions
began to focus on experiments, research and education using
microscopes, with many students studying abroad in Europe
and the United States. This led to global-level achievements
by Japanese scholars, such as Kitasato Shibasaburō (clean
culture of tetanus bacillus in 1889, developed serotherapy in
1890, discovered plague bacillus in 1894), Shiga Kiyoshi(discovered dysentery bacillus in 1897), Takamine Jōkichi(invented the Takadiastase enzyme in 1894, discovered
adrenalin in 1900) and Noguchi Hideyo (research on syphilis
spirochete and yellow fever). Microscopes were also used insericulture, which was growing into a major Japaneseindustry at that time, for quality control of silkworm eggs.

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. MarchThis was a major market for imported microscopes at thetime. Microscope imports began to boom around 1887
(Figure 4.4). There was greater demand for the more
affordable Leitz products than for the high-quality Zeiss
products. Reichert products and American microscopes werealso imported. Some attempts were also made at producing
microscopes in Japan at this time.

Fig. 4.4 Examples of Imported Microscopes from the Late
Meiji Period 5)a) Zeiss Iab) Leitz IV (both held by Hamano MicroscopeCo., Ltd.)

difficulties and repeated improvements before finallypresenting the microscope under Terada’s name at the Tokyo
Taisho Exhibition at Ueno Park in 1914, where they won
bronze (the Tanaka microscope won silver at this Exhibition)11). Matsumoto Fukumatsu of Iwashiya Matsumoto Kikaiten,
the long-standing medical instrument store that had imported
German microscopes, had long dreamed of a Japanese
microscope that could hold its own against the products fromoverseas. Matsumoto met with registered owner Terada andmanufacturers Katō and Shintō for some discussions aboutfurther improvements to the quality of the microscope andhow to work towards manufacture and sales. Taking this on
board, the three worked hard to improve their product andfinally produced a microscope of satisfactory quality. They
named this microscope (Figure 4.6) the “M & Katera”, using
the first letters of Matsumoto, Katō (& Shintō) and Terada. In
1915, the following year, Matsumoto established M & Katera
Optical Works as the manufacturing division and started
developing, selling and advertising microscopes.
Coincidentally, the outbreak of the First World War in 1914
made it difficult to import microscopes into Japan, whichmeant a favorable start to production and sales. Tanaka Shoji
Co., Ltd. (the new name of Tanaka Partnership) and M &Katera Optical Works both suffered heavy damage to theiroffices and factory in the Great Kanto Earthquake of 1923.
While Tanaka withdrew from microscope manufacturing,
Matsumoto was determined to turn disaster into opportunity
and weathered the storm by engaging in technologicaldevelopments to produce high quality microscopes.

4.2 The Birth of the Japanese Microscope 1) 6) 7)
Although several Japanese microscopes were exhibited atthe 4th National Industrial Exhibition held in 1895 in the late
Meiji Period, these were far from practical, withmagnifications of only around 20×. The first commercial
advertisement for a Japanese microscope appeared in the
medical journal “Chūgai Iji Shinpō Vol. 697” in 1909, for a
microscope by Iwashiya Iwamoto Tokichi, listed as “theIwamoto purely Japanese microscope”. The quality of the
microscope is unknown, although it had a maximum
magnification of 600× and was about half the price of animported microscope. As there are no existing versions of
this product and no later records of it, it is thought to haveprobably been a limited edition 7) 8).
The earliest Japanese microscope to be industrially mass
produced was the “Tanaka microscope” (Figure 4.5, 600×dry), manufactured in 1907 by Tanaka Mokujirō (Tanaka
Partnership) 8). It won gold at the Tokyo Industrial Exhibition
held the same year. A catalog9) 10) was published thefollowing year, and production grew to around 100
microscopes per month. It was also shown at the JapanBritish Exhibition held in London in 1910 and won bronze.
Katō Kakitsu (in charge of the lenses) and Shintō Shinkichi(in charge of the mechanisms) started out making microscopein 1910, modelled on the Leitz IV. After much trial and error,
the two completed their first prototype in 1912. They werejoined by Terada Shintarō, who worked hard to leverage theirskills to present the microscope as a domestic product at an
Exhibition. The three men worked through repeatedFig. 4.5 Tanaka
Microscope 15)

Fig. 4.6 M & Katera
Microscope 16)

Yamashita Takeshi, an associate of Terada, joined in the
mission to produce a Japanese microscope that would equal
those from overseas. In 1919, he established TakachihoWorks (renamed Olympus Optical Co., Ltd. in 1949, thenOlympus in 2003, referred to below as Olympus). Terada was
a company director and served as technology supervisor for
microscope manufacturing. Suzuki Taiichi, a former
apprentice of Katō, was in charge of lenses and assembly.
The following year, they completed 20 of their firstmicroscope, the “Asahi” (Figure 4.7). The “Olympus”

Systematic Survey on Optical Microscope Technology in Japan

23

trademark was registered that same year. After that, thecompany worked hard to develop high-performancetechnology and began to make great progress from the late
1920s 12) 13).

Fig. 4.8 Kalnew
Microscope 5)

Fig. 4.7 The Asahi 17)

Katō worked with Shintō to establish Kalnew OpticalIndustries (now Shimadzu Device Corporation) in 1924. The
company started manufacturing microscopes (Figure 4.8) andsupplying lenses for the M & Katera. Suzuki of Olympus
established the Toyo Optical Company in 1927 andannounced its first microscope, the “Eliza” (company closed
in 2002).
In 1934, M & Katera Optical Works changed the name ofits microscope to the Tiyoda microscope, after a microscope
developed by Shintō and the team. The company re-launchedunder the new name of Tiyoda Optical in 1942 (referred to
below as Tiyoda). Thus, the three men who developed the M& Katera and its technologies laid the foundation for later
developments in the Japanese microscope industry.
In 1917, Iwasaki Koyata, president of Mitsubishi
Partnership, funded a merger between the optical instruments
division of Tokyo Keiki and the reflector division of Iwaki
Glass, aimed at domestic production of optical instruments.
Nippon Kogaku K.K. (Japan Optical Industries Company)
was established (renamed Nikon in 1988, referred to below as
Nippon Kogaku and as Nikon after the name change) andvery soon merged with the Fujii Lens Factory. In 1921, thecompany engaged eight optics and precision engineers from
Germany and saw rapid improvement in its technology. Oneof these German engineers, Heinrich Acht, produced
mathematical designs for various lenses, including
microscope lenses and photography lenses. Acht’s design
data and German design methods served as a basic design
resource for later photographic lenses. Nippon Kogaku
released its first microscope, the “JOICO” (Figure 4.9), in
1925, based on Acht’s design.

Fig. 4.9 The JOICOMicroscope 18)

From the late 1920s onwards, with Japan growing
increasingly militant, the main orders received by microscope
manufacturers were military related. Portable microscopes
were developed that could easily fold down into a wooden
box. These were sold in great numbers. Companies made useof their optics technologies and began producing opticalmilitary equipment, such as binoculars, periscopes and sights.
In 1938, Olympus developed the Super Photo, a universal
microscope equipped with photographic equipment (the“Universal”, Figure 4.10). Capable of both biological andindustrial applications, the microscope was equipped forreflected and transmitted light bright-field/dark-fieldobservation and had built in devices for photography,
projection and drawing. This was the highest quality
microscope produced in Japan before the war. Although only
a few were sold, this model indicates the level of technology
at the time and served as the forerunner to the company’s
postwar high-end universal measuring microscopes, thePhotomax and the Vanox. Toward the end of the war,
factories had to decentralize their operations due to frequent
air raids. Olympus relocated its microscope division to aplant in Ina, Nagano in 1944. However, the main offices andfactory were heavily damaged in an air raid on Tokyo in May
1945. Such was the situation when the war ended in August.

Fig. 4.10 The “Universal” Super Photo Universal
Microscope Equipped with Photographic Equipment 17)

4.3 Revival of the Microscope Industry
The end of the war in 1945 was followed by a time of24

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. Marchuncertainty. Optical companies faced drastic staff cuts
(Nippon Kogaku went from 25,000 employees to 1,724
employees), factory closures and administrative cuts. On topof that, all industries had to transition from war industries topeace-time industries. However, the Japanese optical industry
recovered relatively quickly, having made great technologicalprogress before and during the war. In January 1946,
members of 73 companies founded the Japan Optical andPrecision Instruments Manufacturers’ Association (president:
Hatano Yoshio of Nippon Kogaku), with the aim of working
together to develop the optical instruments industry in the six
divisions of filming equipment, cameras, telescopes,
microscopes, surveying equipment and precision measuring
equipment. In June 1954, the Association changed its name to
the Japan Optical Industry Association, while the divisions
also changed their names, e.g. the Japan Microscope
Manufacturers’ Association, which continue to the presentday (the association has seven divisions following theestablishment of the Japan Photo and Imaging Accessory
Association and the Japan Medical-Optical Equipment
Industry Association and after the Japan Motion Picture
Equipment Industry Association left the association).
Microscope manufacturer Tiyoda had escaped any war
damage to its factory and resumed production in December
1945 with Shintō as company president. In addition to its
prewar high-end microscope, the ACM (Figure 4.11), and its
portable microscopes, the company also developed a research
microscope, the LCM (Figure 4.12), in 1947, based on the
Zeiss L. Olympus resumed production at its factory in Ina,but had to refit new machinery, equipment and tools. It
produced its first G microscope (Figure 4.13) in July 1946,
while production of its prewar high-end microscope, theUCE, resumed at the end of 1948. Nippon Kogaku had thenation’s best optical technology capabilities and went intofull-scale microscope development and production right after
the war. Production began on the popular O model (Figure4.14) in 1948 and on the high-end oil-immersion K model(Figure 4.15) in 1949. Many other microscope manufacturers
were established after the war (Appendix 2). With increasing
demand for progress in all industries, the microscope industry
began to revive and grow as postwar medical, welfare,research and education institutions were established andexpanded.

Fig. 4.11 Tiyoda ACM 7)

Fig. 4.12 Tiyoda LCM-Bi 7)

Fig. 4.13 Olympus GK 17)

Fig. 4.14 Nikon O 14)

Fig. 4.15 Nikon K 14)

4.4 Creation of Microscope-Related JIS
After the war, much attention was drawn to the importanceand potential of Japanese microscopes as export products
beyond domestic demand. Standards relating to theirperformance and accuracy were urgently needed. In January
1947, the microscope division of the Japan Optical andPrecision Instruments Manufacturers’ Association draftedsome industrial standards for microscopes. These were put up
for deliberation by the microscope committee of the JapaneseIndustrial Standards Committee precision instrument division(chairperson: Hiroshi Kubota, professor at the University ofTokyo) and enacted in October 1948 as JES 7132
Microscopes (JIS B 7132 from December 1949, now JMMAMIS 1001). The result of examining microscopes around theworld, the standard defined specifications such as size
tolerance and eccentricity of various components,
magnification calculation error, image resolving power andperipheral performance. An issue at the time was that it wasdifficult to find something suitable for a test specimen tomeasure microscope resolving power, as it had to be mass
produced identically, have the appropriate microstructure andnot change over time. This was solved by Tiyoda with the
production of a plastic replica diffraction grating, plated on
an angle in a vacuum to form a light and dark grid, thencoated with an emulsion of microparticles 7). Test plates No.1

Systematic Survey on Optical Microscope Technology in Japan25

(300 grooves/mm) and No. 2 (600 grooves/mm) were definedin JES 7140 (now MIS 8602). Figure 4.16 shows a later No. 1
test plate produced by Nippon Kogaku and a partial
photograph of the magnified image. The defect parts of thegrating pattern are useful to assess performance (resolution,
aberration, etc.). By 1951, 11 JIS had been created, covering
areas such as small biological microscopes,
stereomicroscopes, objective thread and graticules foreyepieces, further completing the JIS coverage of
microscopes. Appendix 1 shows a summary of the ISO, JIS
and MIS standards relating to optical microscopes at the timeof writing this report.
Fig. 4.18 Zeiss Photomicroscope (cut-open model to show
the interior structure) 20)

Fig. 4.16 Test Specimens 19)a) Test plate No. 1b) Partial photograph of magnified
grating pattern

4.5 Development of Research Microscopes
Resuming operations after the war, the West German
branch of Carl Zeiss GmbH released the Zeiss “Standard”
microscope (Figure 4.17) in 1950. Each unit wasinterchangeable and further improvements in function andperformance were added. This was literally the world
standard for high-grade microscopes. In 1955, the company
released the Photomicroscope (Figure 4.18), a high-end
automatic photography microscope with a built-in camera
and automatic exposure device. It was very well received as ahigh-status microscope by the top researchers around theworld.

Prompted by this, Japanese companies began working on
improving their own microscopes further. Nippon Kogaku
launched the S model (Figure 4.19) in 1956, with acoarse/fine movement function that moved the stage up anddown. Later, the company standardized more than 30 types ofunits and incorporated them into an industry-leading multiproduct / multi-function system. The company also
developed Japan’s first Köhler illumination system andincorporated it into the S-Ke model (Figure 4.20), launched
in 1961. In 1957, Olympus developed a new research
microscope, the DF model (Figure 4.21), which had amoveable stage. In 1958, the company launched a clinicalresearch microscope, the E model (Figure 4.22), which was
widely adopted for its high cost performance. By 1963, the Emodel had expanded into the FH model (Figure 4.23) withthe addition of a high precision coaxial coarse/fine movement
device and a built-in light source. Meanwhile, Tiyoda
released a large-scale photography microscope, the Polyphoto(Figure 4.24) in 1958. This was equipped with two 35mm
cameras, a revolving nosepiece fitted with six objective
lenses and a built-in Köhler illumination system. Theseground-breaking specifications for a microscope were very
well received. In 1959, the company launched the R model(Figure 4.25) research microscope together with a specialized
photographic device.

Fig. 4.19 Nikon S 18)
Fig. 4.17 Zeiss Standard 20)

26

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. March

Fig. 4.20 Nikon S-Ke 18)

Fig. 4.21 Olympus DF 17)

Fig. 4.23 Olympus FH 17)

Fig. 4.22 Olympus E 17)

emerged, large flagship model research microscopes weredeveloped, featuring combinations of various units andmultiple functions. Zeiss brought out the Ultraphot, a muchlarger version of the Photomicroscope, while Leitz released
the Ortholux and Reichert the Zetopan. These were worldleading high-end universal microscopes.
Olympus set out to develop a high-end universal
microscope to rival these. In 1966, the company launched the
Photomax (Figure 4.26). With standard units integrated into
the main body of the microscope, this could be used in threeways, as a biological microscope, a metallurgical microscopeor a polarized light microscope. It also had over 20
accessories fitted, including automatic exposure photographic
equipment, making it truly universal. The objective lenses
were also from the newly completed Plan series. In 1967,
Nippon Kogaku launched its own high-end universal
microscope, the Apophot (Figure 4.27). Capable of transillumination, epi-illumination and simultaneous illumination,
it used a Köhler zoom system to match the numericalaperture of the objective lenses for trans-illumination. With
detachable photographic and film devices included as well as
all kinds of observation methods possible, this functional andunique design was produced by an industrial designer.

Fig. 4.24 Tiyoda Polyphoto 7)

Fig. 4.26 Olympus Photomax 17)

Fig. 4.25 Tiyoda R + Photographic Device 7)

Amidst these Japanese developments in the microscopeindustry, the National Museum of Nature and Science and theJapan Microscope Manufacturers’ Association held the“History of Japanese Microscopes” exhibition from
September 8 to October 13, 1963. The exhibition showcased
many microscopes from overseas, antique microscopes andJapanese microscopes. The successful event was even visitedby the Emperor Shōwa and the Crown Prince. A
commemorative book, “Wagakuni no Kenbikyō no Ayumi[History of Japanese Microscopes]” 1) was also published.
Later, as various different methods of observation

Fig. 4.27 Nikon Apophot 18)

Systematic Survey on Optical Microscope Technology in Japan27

Olympus launched the Vanox AH (Figure 4.28) in 1971,
with a stronger frame and greater systematicity. It was also
the first Japanese microscope to incorporate an
epifluorescence device and epi-illumination phase contrast
device. In 1974, the company further developed thesystematicity of the E model and released it as the BH series(Figure 4.29). Both the AH and BH had PlanApo series(1975) and LB series objective lenses. In 1976, the company
launched the CH series for clinical examination and student
training. Japanese high-end research microscopes were
improving in function and performance, steadily catching up
to their European counterparts.
Tiyoda had spearheaded the Japanese microscope industry,both before and after the war, ever since thecommercialization of the M & Katera. The company
developed the MT-A research microscope in 1974 andreleased a further improved model, the MT-B (Figure 4.30),
the following year. Significant improvements were also madein operability, such as a super wide field of view (field
number 26.5) at magnification levels from 1× to very high,with parfocal viewing also possible. Although it was wellreceived for its unique technological specifications, Tiyoda
had ongoing operational difficulties and had to close thefactory in 1976. Sakura Seiki took over its operations, but the
microscope business did not survive. Sakura Finetek Japan is
now in charge of this microscope legacy.

4.6 New Optical Systems and Advances in
Biological Microscopes
In the late 1970s, major progress was made with Japanese
microscopes. Nippon Kogaku adopted a completely new CF
optical system (see 7.4.3) and launched the Microphot V
series in 1976 as the successor to its Apophot high-end
research microscope. The V series consisted of the Biophot(Figure 4.31) for biological and medical applications, theMetaphot for metallurgical and industrial applications, andthe Fluophot for fluorescence microscopy. In July 1978, thecompany launched the Optiphot (X model, Figure 4.32) andthe Labophot (Y model, Figure 4.33) as successors to thestandard high-grade L and S models that had been on themarket since 1956. With the superior performance of the CF
optical system and a novel functional design, thesemicroscopes were well received and significantly boosted theglobal status of Nikon microscopes.

Fig. 4.31 Nikon Biophot V 18)

Fig. 4.28 Olympus Vanox
AHB 17)

Fig. 4.29 Olympus BHA 17)

Fig. 4.32 Nikon Optiphot Fig. 4.33 Nikon Labophot Y 18)
X 18)

Fig. 4.30 Tiyoda MT-B 7)

28

In 1975, Olympus also started working on a completely
revised design of its microscope optical system (the LB
series, see 7.4.3) and alterations to the microscope bodies in
the AH, BH and CH series. However, when Nippon Kogaku
announced its CF optical system and V series, Olympus
hurriedly made some minor changes to the AH (Figure 4.28)
and BH (Figure 4.29) to be able to incorporate the new LB
optical system and released the AH-LB and BH-LB in 1978,

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. Marchthereby preventing any major loss in market share. The
development schedule prioritized the later BH model over theflagship AH model, as it had a greater operational impact.
Thus, the BH2 series was launched in 1980. There four typesof BH2 microscope: the BHS (Figure 4.34) and BHSU,
which had a high luminance 12V 100W halogen light, andthe BHT and BHTU (Figure 4.35), which were slightly
smaller and had a 6V 20W halogen light. The BHSU and
BHTU featured a revolving nosepiece that oriented towards
the arm. The BH2 became a worldwide best seller, being wellreceived for its high-performance LB optical system and its
operability and systematicity. Student microscopes included
the Alphaphot YS (Figure 4.36) with a CF optical system,
launched by Nippon Kogaku in 1983, and the CH2 (Figure4.37), launched by Olympus in 1986 with an LB opticalsystem. Major developments were also made in metallurgical(industrial) microscopes following the changes in biologicalmicroscopes. These are discussed in 6.4.

2)

3)

4)

5)

Fig. 4.34 Olympus BHS 17)

the illumination lens changes to match the magnification.
At the same time, the aperture stop narrows to around
80% of the numerical aperture of the objective lens andthe field stop circumscribes the field of vision. To ensure
constant color temperature, changes in brightness aredone by ND filter selection without changing the lamp
voltage. The above are set automatically and instantly.
Selecting the light path and photographic lens for thecamera (up to three) and video camera is done
electrically by pushing the respective buttons.
When photographing under low magnification, thedifficulty of focusing due to the film and the eye having
different depths of focus is resolved with the world’s firstmicroscope autofocus mechanism. This is based on theprinciple of the image phase detection method (Figure4.38), in which a chopper situated at the exit pupil areaof the photographic lens is rotated at high speed and the
movement of the image is used to determine the amountby which the focus is out 21).
A finder optical system is also incorporated to directly
determine the photographic range. This is devised with a
specially shaped prism to reflect twice and return anerected image, as the image rotates by 30° when thecirculating light path returns to the viewing tube prism.
Various kinds of accessories are included to ensure
universality, such as an epifluorescence unit and a phase
contrast unit.

Fig. 4.35 Olympus BHTU 17)

ChopperImage
sensor

ChopperImage
sensorFilm(Pupil)Chopper

Image sensor

FilterEyepiece
Chopperposition
detector

Fig. 4.36 Nikon Alphaphot
YS 18)

Fig. 4.37 Olympus CH2 17)

Objective lensMemoryStage
position
detector

Calculation
processing

Stage
Condenser
lens

After developing the BH2, Olympus started working on acompletely revised design for the high-end AH (Vanox). The
basic concept was to produce a universal photography
microscope with high-powered optical performance and as
many operations as possible automated or electrified.
1) When changing objective lenses (by pushing a button),Image
sensordriverStage
driverComputerFig. 4.38 Microscope Autofocus a) Principle and b)
Configuration(created from cited reference 21)

Systematic Survey on Optical Microscope Technology in Japan29

With features such as the illumination system, imaging
system (objective lens and eyepiece), photographic systemand finder system all included, this was an unprecedented
complex optical system for a microscope (Figure 4.39). The
AH2 (New Vanox) series was developed to incorporate thesefeatures, with three models launched in 1983: the automatic
AHBS (Figure 4.40), the electric/manual AHBT and theindustrial AHMT. The innovation was welcomed by users,
especially those who took frequent micrographs, and took
German manufacturers by surprise.

Photographic lens (interchangeable)

In 1985, Nippon Kogaku launched the Microphot FX, ahigh-end universal photography microscope featuring an
automatic exposure function and the NCF series opticalsystem (see 7.4), with improved resolution and contrast thanthe CF system. In 1988, the company released the Microphot
FXA (Figure 4.41), with features including autofocus (image
contrast method), an electronic revolving nosepiece and acommunication function. The Alphaphot YS2 (Figure 4.42)
was also released the same year, followed by the new
Optiphot 2 X2 (Figure 4.43) and the Labophot 2 Y2 in 1990.

35mm film

Photometry
systemViewing tube prismAF
photometry
systemImage rotating prism

Field mask
Finder magnifying lensViewing tube
prism

Photographic lensLarge photographic
lensFig. 4.41 Nikon Microphot FXA 18)

Camera/AF lightpath changing
prism

Eyepiece

AF photometry system

Pupil viewing lensIntermediate tube lensObjective lensSpecimen

Condenser lens (1×4× out)

Illumination lens(interchangeable)

Aperture stop

Field stop

Color temperaturechanging filter

12V 100W
halogenlamp

Collector lensFig. 4.39 Olympus AHBS Optical Diagram 17)a) Plan viewFig. 4.42 Nikon Alphaphot
YS2 18)Fig. 4.43 Nikon Optiphot 2
X2 18)b) Side viewThus we see that as a result of Nippon Kogaku andOlympus spurring each other on to remodel their microscopes
and develop new optical systems in the late 1970s and further
improving the functions and performance of Japanese
microscopes, they came on par with their German
counterparts, which had dominated the world since the late
19th century.

4.7 Infinity-Corrected Optical Systems andRemodeling of Biological Microscopes
Following the Photomicroscope and Ultraphoto, Zeiss
went for a long time without producing any further worldclass research microscopes. In 1973, the company released
the Axiomat (Figure 4.44), an innovative large-scaleFig. 4.40 Olympus AHBS and Optical System 17)

30

microscope. Unlike conventional objective lenses with amechanical tube length of 160mm, this used a special

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. Marchinfinity-corrected optical system (see 2.4) that allows an

AH2, BH2, CH2 and IMT2 (inverted microscope, see 6.1)

infinite mechanical tube length. The main body of the
microscope was a solid block that offered a variety of

named the AX, BX, CX and IX respectively. The new design

observation methods through different combinations. While
the technology was highly regarded, the model was not aby the AX and IX in 1994 and the CX in 1997. The body

great success, as it was very expensive and a little difficult to
operate. In 1986, Zeiss launched the highly anticipated Axio
series. This was made up of three models: the Axiophot highend photography microscope (Figure 4.45), the Axioplan
research microscope and the Axiotron industrial microscope.
These featured a new infinity-corrected optical system called
the infinity color-corrected system (ICS). The Axio series had
a huge impact on the industry, once again proving Zeiss’technological prowess and heightening the company’s
reputation. In 1992, Leica brought out a high-end microscope

began with the launch of the BX and UIS in 1993, followed
shape of each series had an ergonomic Y shape design. There
were three models in the BX series: the standard BX40, thehigh-grade BX50 (Figure 4.47) and the BX60
epifluorescence microscope. Many new units and accessories
were also developed, such as a variable tilt angle tube toallow adjustable viewing positions (Figure 2.30d) and various
camera adaptors. The AX (Provis) series also included theAX70 research microscope and the fully automated AX80
(Figure 4.48). These superseded the previous BH2 and AH2models with even greater popularity.

of its own, the DM series (Figure 4.46), featuring its own
Delta (Δ) infinity-corrected optical system.

Fig. 4.47 Olympus BX50 17)

Fig. 4.44 Zeiss Axiomat 20)

Fig. 4.48 Olympus AX80 17)

Nikon changed from its conventional NCF optical system
Fig. 4.45 Zeiss Axiophot 20)

Fig. 4.46 Leica DAS
Mikroskop DMRX
22)

to its new CFI60 infinity-corrected optical system in 1996.
The objective lens parfocalizing distance (see 2.4) also
increased from 45mm to 60mm (see 7.4.4 for details). The
company incorporated this system into the new Eclipse

Olympus considered and debated whether it shouldcompete against Zeiss’ new optical system by enhancing its
LB system and improving functions or by designing acompletely new infinity-corrected optical system. In 1988,
the company opted for the latter. The concept andcharacteristics of this new Universal Infinity System (UIS)biological microscope series, made up of the premium grade
E800 (Figure 4.49), the high-grade E600 (Figure 4.50) andthe E400, all launched at the same time. In 1997, these were
followed by the premium fully automated E1000. The main
Japanese high-end biological microscopes had all transitioned
to infinity-corrected optical systems by around the year 2000.

are discussed in 7.4.4. As well as the UIS, the company also
redesigned its microscope bodies, with the successors to the

Systematic Survey on Optical Microscope Technology in Japan31

Fig. 4.49 Nikon Eclipse
E800 18)

Fig. 4.50 Nikon Eclipse
E600 18)

In 2000, Olympus released the Power BX Plus series, acomplete redesign of the BX series. The series had 12 models
in total, including industrial microscopes such as the BX51,
52, 61, 62, 41 and 45. Key features included improved
functionality in fluorescence imaging and differential
interference contrast imaging, computerized control for
digital imaging and an ergonomic design that was easier touse. In 2010, the company launched the BX3 series, a further
complete redesign of this series. This comprised threemodels: the BX43, 53 and 63. The BX43 is the efficient
viewing model, with a newly developed LED light source
offering improved color reproducibility. The BX53 has
improved illumination and an ecology mode operated bymotion sensor. The BX63 (Figure 5.39) features all kinds ofelectronic units and touch panel operation.

Meanwhile, Nikon launched its Eclipse 80i and 90i uprightresearch microscopes in 1994, as well as the Eclipse 50i and55i clinical upright microscopes. The 80i featured improved
functionality in fluorescence imaging and differential
interference contrast imaging, improved illumination and a
new digital imaging head (DIH) that integrated the opticalsystems for the eyepiece, fluorescence device, photography
port and zoom. The 90i (Figure 4.51), an electronic version of
the 80i, was the premium model in the series, incorporating
new software in an easy-to-use digital imaging system. The
50i and 55i (Figure 4.52) offered improved operability as
clinical microscopes. The 50i used halogen illumination,
while the 55i used LED illumination. In 2011, the company
completely redesigned its series, launching the Eclipse Ni
research microscope series and the Eclipse Ci clinicalmicroscope series. The Ni series came with a fullcomplement of electronic accessories to further improve
operability, as well as better optical performance through theaddition of the new CFI Plan Apo λ series objective lenses(see 7.4.5 (4)). The electronic Ni-E (Figure 4.53) and themanual Ni-U were the two models in this series. The Ci
series comprised three clinical microscope models: the LEDlit Ci-E (electronic), the manual Ci-L and the halogen-lit Ci-S
(manual, Figure 4.54).

Fig. 4.53 Nikon Eclipse Ni-E 18)

Fig. 4.51 Nikon Eclipse 90i with DIH 18)

Fig. 4.54 Nikon Eclipse Ci-S 18)

Fig. 4.52 Nikon Eclipse 55i 18)

32

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. MarchReferences
1) Wagakuni no Kenbikyō no Ayumi [History of Japanese
Microscopes], Science Museum Supporters’ Association,
19632) Kobayashi Y.: Sekai no Kenbikyō no Rekishi [History of
the World’s Microscopes], 1980, pp.1-68
3) Tanaka S.: Kenbikyō no Rekishi [History ofMicroscopes], Kyushu Bunko, Touka Shobo, 1979, pp.
131-139
4) Supplied by the National Museum of Nature and Science5) Supplied by the National Museum of Nature and Science(Hamano Microscope collection)6) Teshima Y.: Nihon no Kōgakukōgyō-shi [History of theJapanese Optical Industry], 5th edition, Chapter 2 Section
1 Kenbikyō [Microscopes], Optical Industry History
Editorial Committee, Dec. 1955, pp. 422-426
7) Tiyoda Kenbikyō no Rekishi [History of Tiyoda
Microscopes], Sakura Seiki, 1994, pp. 32-108
8) Inoue R.: Meiji Jidai no Kokusan Kenbikyō ni kansuru
Oboegaki [Notes on Japanese Microscopes in the Meiji
Period], Journal of the Kansai Branch of the JapaneseSociety for the History of Medicine No. 86, pp.16-24,
20079) Tanaka Microscope Catalog, Tanaka Partnership, 1908
10) Physics and Chemistry Instruments and Chemical
Specimen Inventory, Tanaka Partnership, 1908, pp. 269270

11) Overview of Tokyo Taisho Exhibition Exhibit Reviews,
Part 1 Education and Arts, Category 11 winners, silver
medalists p. 33, bronze medalists p. 111, 191412) 50-nen no Ayumi [A 50-Year History], Olympus OpticalCo., Ltd., 1969, pp. 3-110
13) Kusetsu jūsan-nen Orinpasu Kenbikyō/Gentō-ki/Eisha-ki
no Keireki [Thirteen Hard Years: The Career History of
Olympus Microscopes, Slides and Projectors], TakachihoWorks Co., Ltd., 1932
14) Hikari to Mikuro to Tomoni - Nikon 75-nen-shi [Lightand Micro Together: A 75-year History of Nikon], 1993,
pp. 19-20, 40-44
15) Supplied by the National Museum of Nature and Science(Inoue Ryō collection)16) Supplied by Sakura Finetek Co., Ltd.
17) Supplied by Olympus Corporation
18) Supplied by Nikon Corporation
19) Supplied by Japan Microscope Manufacturers’
Association
20) Supplied by Carl Zeiss Co., Ltd.
21) Horikawa Y.: Kenbikyō-yō Jidō Shōten Sōchi[Automatic Focus Devices for Microscopes], Japanese
Journal of Optics, Vol. 13 No. 4, Aug. 1984, p.320
22) Supplied by Leica Microsystems

Systematic Survey on Optical Microscope Technology in Japan33

5

Development of Various Microscopy
Techniques 1) 2) 3)

The 20th century has seen the development of various
methods of viewing objects by microscope. This has gone
beyond simply viewing objects under ordinary natural light toapplying various characteristics of light, such as refraction,
scattering, diffraction, interference, polarized light andfluorescence, to bring out objects and information that would
otherwise be invisible to the naked eye. It is no overstatement
to say that no other optical instrument makes use of as broada range of the properties of light as the optical microscope.
This chapter discusses the principles of different microscopy
techniques and the history of their development in Japan andoverseas.

5.1 Bright Field Microscopy
Bright field microscopy is the most common method usedwith optical microscopes. The illuminated specimen isenlarged by the objective lens and further enlarged by theeyepiece, and then either displayed or recorded by camera orvideo. Many specimens are viewed directly (Figure 5.1a)with bright field microscopy. Anything that is too transparent
to see easily can be viewed with contrast by narrowing theaperture stop of the condenser. However, viewing more
infinitesimal structures requires fixing the specimen in placeand slicing off sections with a device called a microtome.
Since this causes most specimens to become transparent, aprocess called staining is used to color the specimen with a
special dye. The techniques for this process were establishedin the late 19th century. Even today, bright field microscopy
for observing stained specimens is a common use for optical
microscopes, widely used in medical and biological researchand examinations (Figure 5.1b,c). However, since thestaining method requires the specimen tissue to be fixed inplace for coloring, the drawback is that it either destroys theorganism or severely impairs its functions, meaning it cannot
be used to observe specimens in a living state.

5.2 Dark Field Microscopy
If the light illuminating the specimen is prevented fromentering the objective lens, the only light entering theobjective lens is that which is reflected, scattered ordiffracted from the specimen against a pitch-black field. The
advantage is that this requires no fixing in place, staining orother pre-processing of specimens, meaning that specimens
can be observed live. This makes it possible to view thepresence and movement of colloidal particles (several
nanometers in diameter) and bacteria flagella (around 20nm
in diameter), far smaller than the microscope resolution limit(around 200nm).
Dark field microscopy is achieved by simply including adark field condenser, which is designed with a greater
numerical aperture (NA) than the objective lens, so that thelight only shines on the specimen. Types of dark field
condensers include the simple type (Figure 5.2a), which has aring stop on the light source side of an ordinary large aperturecondenser, and special dry (Figure 5.2b) and oil (Figure 5.2c)
types. Special condensers concentrate the light on thespecimen and have a cardioid or similar spherical surface(Figure 5.2b-c, second reflection). Dark field microscopyusing an oil immersion objective with a high NA of around
100× requires an iris diaphragm built into the objective lensitself.

Fig. 5.2 Different Types of Condensers 1)a) Simple

Fig. 5.1 Example Photos of Bright Field Microscopy 1)a) Butterfly scales(not stained)

34b) Kidney (H&E
stained)c) Chromosomes(Giemsa stained)b) Special (dry)c) Special (oil)The first dark field condenser is thought to have been aparaboloid reflector made by British engineer F. H. Wenhamin 1850. Austrian-born chemist R. Zsigmondy (1865-1929)
worked with Zeiss optical researcher H. Siedentopf to inventand develop the ultramicroscope in 1903 for studying
colloids. This dark field microscope prototype illuminated thespecimen from the side, so that light scattered off theparticles of the specimen instead of directly entering theobjective lens. Zsigmondy used the ultramicroscope toresearch colloidal particles far smaller than the resolution
limit of the optical microscope and was awarded the Nobel
Prize in Chemistry in 1925. Dark field microscopy is still

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. Marchused to study things in the nanometer order, such as bacteria
flagella or gold colloid indications in biological and chemical
examinations. Figure 5.3 shows an example photograph using
dark field microscopy.

Fig. 5.3 Example Photograph using Dark Field
Microscopy (Water Flea) 1)

5.3 Phase Contrast Microscopy
Light has the physical properties of a wave. When light issensed by the human eye, photographic film or electronic
image sensor, the amplitude is perceived as brightness
contrast and the wavelength is perceived as color contrast.
However, phase objects that absorb very little of the light
passing through them, such as biological tissue sections andculture cells, can be difficult to perceive, as they are colorlessand transparent (Figure 5.4). Phase contrast microscopy
makes these infinitesimal, colorless and transparent
specimens visible by using light diffraction and interference
to change the light and dark contrast.

through the phase film. As a result, if the phase of the light
passing through the phase film is set to move forward by only
quarter of a wavelength, the phases of the direct wave and thediffraction wave differ by half a wavelength and theamplitude I’ of the compound wave is less than that of thedirect wave (background brightness). That is, a dark contrast
image is formed of the phase object, which has a higher
refractive index than its surroundings. The contrast can befurther increased by having an absorption film on the phase
plate and reducing the intensity of the surround wave (Figure5.6b). This is called positive (or dark) contrast. Similarly,
delaying the phase of the light passing through the phase
plate by only one quarter of a wavelength causes the phase of
the direct wave and diffraction wave to coincide, thereby
increasing the compound wave amplitude I’’ to greater thanthat of the direct wave, making the phase object brighter thanits surroundings (Figure 5.6c). This is called negative (orbright) contrast. Figure 5.7 shows photographs comparing thetwo. Phase contrast microscopy is widely used for studying
live specimens such as culture cells.

Phase
plate
Diffraction wave D

Phase contrast
objective lensDirect wave S

Specimen
Condenser

Ring stop

Fig. 5.5 Structure of a Phase Contrast Microscope1)
Amplitude A

Wavelength λa) Waveform after passing through phase object

Amplitude A’

No object

Direction of light

Phase object

Transmitted
wavefront

Amplitude A’

Amplitude A’

Amplitude object≈ λ/4
λ (1 wavelength)b) Waveform after passing through phase film (positive)

Phase delay

Fig. 5.4 Changes in Light Passing Through an Object 1)

Phase contrast microscopes are structured as shown in
Figure 5.5, with a ring stop at the front focal point of thecondenser and a phase plate with a ring-shaped phase film atthe conjugate back focal point of the objective lens. Figure
5.6 provides a simple explanation of the principle. The phaseshifted wave P that passes through the phase object can beconsidered as the sum of the direct wave S that is unaffectedby the object and the diffraction wave D. If the difference inphase is small enough at this point, the phase of thediffraction wave D is only delayed by one quarter of awavelength behind the direct wave S. While direct wave S
passes through the phase film, diffraction wave D isdiffracted by the phase object and only part of it passesc) Waveform after passing through phase film (negative)

Fig. 5.6 Phase Contrast Principle 1)

Fig. 5.7 Phase Contrast (fibroblast) 1)
a) Positive (Dark)b) Negative (Bright)

Systematic Survey on Optical Microscope Technology in Japan35

Dutch physicist F. Zernike (1888-1966) studied Abbe’s
theory of microscope imaging and published the principle ofphase contrast microscopy in 1932. Zeiss completed a phase
contrast microscope prototype in 1936 and published a paper
on it in 1941, during the Second World War. In 1943, thecompany also successfully filmed cell division, which gained
attention worldwide. As soon as the war was over, the UnitedStates began building phase contrast microscopes. In 1953,
Zernike was awarded the Nobel Prize in Physics for his workon the ground-breaking method of viewing living things, suchas culture cells and chromosomes (so called because they
were previously invisible without being stained), in clear
contrast.

Fig. 5.9 Tiyoda Phase Contrast Device PI 6)

Fig. 5.10 Olympus Phase Contrast Device PA 8)
Fig. 5.8 Zeiss Phase Contrast Microscope Prototype 5)

In Japan, Prof. Kubota Hiroshi of the University of Tokyo
Second Faculty of Engineering took note of Zeiss’ paper andmade recommendations to Tiyoda. Joint research began in1948 6). Miyata Shōichi of Olympus also took note of Zeiss’
paper and began research and development of his own. Prof.
Dan Katsuma, then professor at the University of Tokyo
Misaki Marine Biological Station in Aburatsubo Bay,
Kanagawa (later president of Tokyo Metropolitan
University), owned Japan’s only phase contrast microscope,
an early model made by American company Bausch & Lombbrought over by Dan’s American wife, Jean. They werevisited so frequently by developers from Tiyoda andOlympus observing and comparing prototypes that it became
known as the “Misaki pilgrimage”. In April 1949, Tiyodapresented Japan’s first phase contrast microscope to the Japan
Society of Applied Physics7) and caused a sensation (Figure5.9). Olympus put out a 30th anniversary publication in
October that year, although its adoption of a vacuum
deposition method that made it possible to mass produce
phase film (Figure 5.10) gained more attention 8). In
December the same year, the Phase Contrast Microscope
Symposium (later Research Society) was founded. Throughits publication 9) 10), the group made significant contributions
to users and manufacturers, such as spreading information on
the utility of phase contrast microscopes and how to use
them. Nippon Kogaku and other Japanese microscope
manufacturers also began developing and producing phase
contrast microscopes. These microscopes spread rapidly
throughout Japan, contributing to developments in biology.

36

5.4 Polarized Light Microscopy 11) 12) 13)
The polarized light phenomenon, whereby light polarizes
in the direction of oscillation (see 2.1.3 (3)), was discoveredin 1808 by French physicist E. Malus (1775-1812) observing
light reflected off a palace window through a birefringent
calcite crystal. In 1828, Scottish geologist W. Nicol (17701851) invented the Nicol prism (Figure 2.17) by cementing
together two calcite prisms, enabling him to turn natural light,
which has a random oscillation direction, into linearlypolarized light with a regular oscillation direction. He also
devised other polarizing equipment and studied other rocks
and minerals. In 1834, British scientist H. F. Talbot (18001877, also known for his invention of the calotype
photographic process) invented the polarized lightmicroscope using Nicol prisms in the illumination optical
path and the viewing optical path. In 1851, British geologist
H. C. Sorby (1826-1908), a known pioneer in specimen
staining, began using a polarized light microscope to study
the crystalline structure of rocks and minerals. This work wascontinued by German geologists F. Zirkel (1838-1912) and
H. Rosenbusch (1836-1914), laying the foundations for the
golden age of petrography. However, the Nicol prisms usedin polarized light microscopes were expensive and had anarrow viewing angle. These issues were resolved in 1929
with the invention of a thin polarizing plate by American
physicist E. H. Land (1909-1991), who named his invention“polaroid”. Various improvements followed, resulting in an
inexpensive and highly efficient polarizing element, used in

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. Marchsunglasses and photographic filters and eventually becoming
standard in polarized light microscopes.
The basic structure of a polarized light microscope
comprises a bright field microscope with two polarizing
plates, the polarizer on the condenser side and the analyzer on
the objective lens side. The polarizer and analyzer are placedso that their direction of oscillation is at right angles (calledcrossed nicols), allowing clear viewing of an opticallyanisotropic (birefringent) material against a darkened
background. There are two main types of polarized lightmicroscopy. The basic method involves lowering thenumerical aperture of the illumination (placing the top lens of
the polarization condenser out to the side) and viewing thebirefringence of the specimen with a low-magnification
objective lens of around 4-10×. This is called the orthoscope(Figure 5.11a) and uses test plates (wave plate, sensitive tint
plate) and a compensator (compensation plate). The othermethod involves increasing the numerical aperture of theillumination (placing the top lens of the polarization
condenser into the optical path) and viewing the interference
fringes (representing the optical characteristics of the crystal
specimen) produced near the back focal point of the high NA
objective lens. This is called the conoscope (Figure 5.11b)
and uses a Bertrand lens in the viewing optical path to makeit easier to view the conoscopic image. Professional polarized
light microscopes also have other components in addition to
the polarizer and analyzer, including a rotary stage toprecisely determine the orientation of the sample, test plates
for changing the polarization state, compensators(compensating plates) to measure the birefringence of thespecimen and an eyepiece with cross lines.

The objective and condenser lenses between the polarizer andanalyzer also need to be specially designed for polarization toprevent any optical strain that can cause birefringence. Test
plates can include quarter wave plates, which change thepolarization from linear to circular (or vice versa), half wave
plates, which change the direction of linear polarization or
the rotation of circular polarization, and sensitive tint plates(or one wave plates), which change slight differences inbirefringence into clear colors such as yellow, red or blue.
These plates are made by sandwiching sections of mica or
crystal between two glass plates, although more are now
being made from polymer materials. The compensator is a
device used to measure the birefringence (retardation, see
2.1.3 (3)) of the specimen. These vary by measurement range
and precision, and include the Berek (Figure 3.11) type, theSénarmont type and the Bräce-Köhler type. Figure 5.12 a)shows an orthoscopic image (biotite gneiss, using a sensitive
tint plate), b) shows a conoscopic image of a uniaxial crystal(calcite) and c) shows a conoscopic image of a biaxial crystal(topaz).

(conoscopic image)(orthoscopic image)
Image

Bertrand lensAnalyzer
Test plate /Compensator
Strain-freeobjective lens(lowmagnification)

Interference
fringes(highmagnification)

Fig. 5.12 Polarized Light Photomicrographs 1)a) Orthoscopic image: biotite gneissb) Conoscopic image: calcite (uniaxial crystal)c) Conoscopic image: topaz (biaxial crystal)Specimen

Strain-freecondenser

Polarizer

Fig. 5.11 Polarized Light Microscope Structures 1)a) Orthoscopeb) Conoscope

As previously mentioned, polarized light microscopes
have mainly been used for studying rocks and minerals. As
such, they are also called ore microscopes. In Japan,
Takachiho and Shimadzu jointly produced a mineral
microscope (Figure 5.13) in 1925. In 1949, the Polarization
Microscope Committee was established (with Prof. Emeritus
Tsuboi Seitarō of the University of Tokyo as president) with

Systematic Survey on Optical Microscope Technology in Japan37

the aim of producing proper polarized light microscopes inJapan. In 1951, Nippon Kogaku released its POB polarized
light microscope, funded by a Grant-in-Aid for Scientific
Research from the Ministry of Education, Science andCulture. This was followed by the proper POH polarized lightmicroscope (Figure 5.14) in 1952 14). Olympus launched thePOM (Figure 5.15) in 1960, followed by the POS in 1963.
Since then, each company has produced its own polarized
light microscope system as part of its lineup of units.

oscillation direction of the polarizer. Even after the lightpasses through the analyzer, the pupil of the objective lens is
not completely dark, which causes the formation of a darkcross, known as an isogyre, and deterioration in polarization
performance. This issue was resolved with a rectifier
produced by Inoue Shinya et al. in 1957 15) 16). As shown in
Figure 5.16, the rectifier comprises a combination of a halfwave plate paired with a lens with no refractive power. The
rectifier compensates for the rotation of the polarized lightfrom the lens and is situated with the condenser on the object
side (Figure 5.17). This allows a highly polarized opticalsystem. Inoue also developed video microscopy using image
processing to amplify images with poor contrast. By making
faint birefringence visible for cell division, he was able toidentify the presence of spindles and the cell division
mechanism. The rectifier was commercialized by Nippon
Kogaku in 1975 with the Apophot (Figure 5.18).

Lens with no refractive power

Fig. 5.13 Olympus/Shimadzu Ore Microscope 4)

Polarizer

Half wave plate

Objective lens

Incident linearlypolarized light

Polarized light fromthe objective lensAnalyzer

Polarized light from the halfwave plate

Polarized light from the lens with norefractive power

RectifierFig. 5.16 Explanatory Diagram of a Rectifier (objective lenssection only)(created with reference to cited reference 15)

Fig. 5.14 Nippon Kogaku POH Polarized Light
Microscope 17)

Field stop

Compensator

Polarizer

Half wave plate

RectifierSpecimen

Condenser lensHalf wave plate

Objective lensRectifierAnalyzer

Eyepiece

Fig. 5.17 Rectifier Optical System(created with reference to cited reference 15)

Fig. 5.15 Olympus POM Polarized Light Microscope 4)

Objective and condenser lenses for polarized lightmicroscopes are designed to prevent optical strain. However,rotation of polarization is inevitable due to the sphericalsurface of the lens. The amount of rotation is proportionate to
the numerical aperture of the objective lens. The highest
amount of light leakage occurs at an angle of ±45° to the38

Fig. 5.18 Nippon Kogaku Rectifier Microscope 17)

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. MarchRecent methods have been proposed for enabling
microscopes to directly compensate for deterioration inpolarization using a polarizing liquid crystal element
combined with image processing technology. It is now
becoming possible to sharpen the viewing image and takevarious quantitative measurements.

5.5 Differential Interference Contrast
Microscopy (DIC)
Differential interference contrast (DIC) microscopy makes
it possible to see phase information of a colorless andtransparent object using interference color contrasts onpolarization interference. Figure 5.19 shows the structure andprinciple of how this works.

Vibration direction oflight viewed from above
Interference image(difference in two wavefronts)
Analyzer

Aligned in the same
vibration direction

Two wavefronts joined

Wollaston prism 2

Two separate lightwaves combined

Objective lensSpecimen transmitted wavefront
Specimen (phase object)

Shearing value (lower than
the resolving power)

Two light waves
continue separately

Condenser lensSheared wavefronts

Wollaston prism 1

Incident wavefront
Polarizer

Light waves bisecting withvibration directions at rightanglesLinearly polarized
light

Natural light

Françon in 1947. The first and second Wollaston prisms must
be located at the front focal point of the condenser lens andthe back focal point of the objective lens, respectively.
However, this is difficult in practice, as the back focal pointof many objective lenses falls inside the lens itself. In 1952,
Polish and naturalized French physicist G. Nomarski (19191997) resolved this with the invention of the Nomarski prism(Figure 5.20b), which has one of the Wollaston prism optic
axis on an angle 18). The Nomarski system is the main type ofdifferential interference microscope currently used. Nomarski
DIC microscopes have respective prisms for the condenser
lens and the objective lens, although this can be done in two
ways. One way is to have a prism on the condenser side foreach objective lens and one shared prism on the objective
lens side. The other way is to have the prisms on thecondenser side categorized by the numerical aperture of theobjective lens and have separate prisms on the objective lensside. Adjusting the background contrast can be done either byshifting in the lateral direction of the prism on the objective
lens side or by the Sénarmont method, which includes apolarizer that rotates with a quarter wave plate below thecondenser. These microscopes are most commonly used witha gray contrast background, as this makes the specimen themost visible, although they can be further adjusted using
sensitive color to give bright yellow, red or blue contrast. The
Nomarski prism is made of crystal material and needs to bepolished with minute-level accuracy for the optic axis andsecond-level accuracy for the wedge angle. This makes it oneof the most difficult optical components to manufacture.
Figure 5.21a shows a DIC photomicrograph of a diatom.
Figure 5.21b shows a comparison photomicrograph takenusing a phase contrast microscope.

Figure 5.19
Structure and Principle of Differential
Interference Contrast Microscope(created with reference to cited reference 19)

The linearly polarized light passing through the polarizer
below the condenser (vibration direction shown to the right of
the image) first travels into the first Wollaston prism (Figure
5.20a, a combination of two crystal prisms joined together
that are cut at a narrow wedge angle to have a specificdirection) and splits into two linearly polarized light waves
with vibration directions at right angles to each other. The
two light waves pass through the phase object, undergo
wavefront deformation and then pass through the objective
lens before being combined again by the second Wollaston
prism. The analyzer aligns the vibration direction, causing
interference corresponding to the difference in the two
wavefronts. At this point, if the separation (shearing value)
between the two light waves passing through the phase object
is less than the resolving power of the objective lens, theimage does not double up and has an interference contrast
corresponding to the phase difference (the differential
coefficient of the transmitted wavefront). As a result,differential interference contrast images have a relief-likethree-dimensional feel. This method of differential
interference contrast microscopy was invented by British
microscope designer F. Smith and French physicist M.

shows the optic axis direction of the crystal
shows the vibration direction of the linearly polarized light

Fig. 5.20 a) Wollaston Prism and b) Nomarski Prism

Fig. 5.21 DIC Photomicrographs 1)a) Diatomb) Rat embryo (top: phase contrast; bottom: DIC)

Systematic Survey on Optical Microscope Technology in Japan

39

The Nomarski DIC device for microscopes wascommercialized by Zeiss in 1965 20). In Japan, Yamamoto
Tadaaki of Nippon Kogaku, together with Françon, publishedtheir own theory on differential interference contrast in 196221) 22). In 1966, Nippon Kogaku released the T model
biological DIC microscope (transmitted light type, Figure
5.22a) and the R model metallurgical DIC microscope(reflected light type, Figure 5.22b). Meanwhile, Union
Optical obtained a license for the Nomarski system anddeveloped it for industrial microscopes in 1971 (Figure 6.54).
Olympus also obtained a sublicense and launched its own
Nomarski interference contrast (NIC) device in 1973 forindustrial microscopes (Figure 6.55) and in 1974 forbiological microscopes. These were used with the Vanox(AH) and the BH. Figure 5.23 shows a NIC device for the
BH. From the left, the items are an intermediate tube
(Nomarski prism and analyzer on the objective lens side), a
centering telescope, a condenser and three Nomarski
objective lenses.

Fig. 5.22 Nippon Kogaku Yamamoto-Françon DIC
Microscopes 17)a) Transmitted light type S-Ke-T

strain as possible, meaning specimens in plastic containers
cannot be used. Nevertheless, unlike phase contrast
microscopy, it allows viewing of thick specimens without
difficulty and without a halo appearing. The two systems of
microscopy have complementary image characteristics andare used according to purpose as required. In recent years,
microscopes are being designed in response to user needs,
such as having prisms with different shearing values,
depending on specimen thickness.

5.6 Modulation Contrast Microscopy (MC)Another method for viewing phase objects is modulation
contrast (MC) microscopy (also called relief contrast
microscopy) 23), devised by American R. Hoffmann in 1975.
As shown in Figure 5.24, this is structured with a rectangularslit off the optical axis placed at the front focal point of thecondenser lens and a modulator placed at the conjugate backfocal point of the objective lens. The modulator has threeareas, bright (B), gray (G) and dark (D), as shown in the
figure. The image from the slit is adjusted so that it isprojected into the G area. Polarizing plate P1 is attached tothe slit and P2 is below it. Rotating P2 alters the width of theslit and the amount of light, making it possible to adjust thecontrast of the image. If the specimen has a low refractive
index gradient, light refracts from the slit into the B or D
areas of the modulator. Adding a light-dark contrast to thatpart produces an image with a three-dimensional feel, like
DIC microscopy (Figure 5.25). Modulation contrast
microscopy has an advantage over phase contrast microscopy
in that there are no image halos, and an advantage over DIC
microscopy in that it is possible to use plastic containers.
Although the resolving power is lower than that of DIC
microscopes, it is comparatively lower priced and is steadily
growing in popularity, particularly for studying culture cells.

b) Reflected light type S-R
Image

Modulator
Objective lensModulator and slit
image after
adjustment

Specimen(phase object)

Fig. 5.23 Olympus Differential Interference Contrast Device
BH-NIC 4)

Condenser
Slit

Since biological DIC microscopes make it possible to view
infinitesimal living phase objects in clear contrast, they areoften used for similar purposes as phase contrast
microscopes. However, differential interference contrast
microscopy requires polarized light, so the condenser,
specimen and objective lens must produce as little optical

40

Slit aperture
P1, P2: polarizing plates

Fig. 5.24 Modulation Contrast Principle 1)

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. MarchJapanese fluorescence microscopes began with the releaseof an ultra-high voltage mercury lamp illumination system by
Nippon Kogaku in 1953. This was followed by the Tiyoda H200 in 1954 and the Olympus HLS in 1963. The first
specialized fluorescence microscopes were the Tiyoda FM200A (Figure 5.26) and the Nippon Kogaku S-FS (Figure5.27), both launched in 1965, followed by the Olympus FLM(Figure 5.28) in 1970, in response to growing demand, suchas fluorescent antibody techniques.

Fig. 5.25 Modulation Contrast Image (nerve cell) 1)

5.7 Fluorescence Microscopy
5.7.1

Transmitted Light Fluorescence Microscopes

Fluorescence is a type of photoluminescence, whereby
light (ultraviolet or visible) energy is absorbed (excitation)and released. Photoluminescence with a short (near non-Fig. 5.26 Tiyoda Fluorescence Microscope FM-200A 6)

existent) light lifespan after the excitation stops is called
fluorescence (photoluminescence with a long light lifespan iscalled phosphorescence). Fluorescence has a longer
wavelength than the excitation light (Stokes law, 1852) and isalso far weaker. A. Köhler of Zeiss built an ultraviolet
microscope in 1904 that used objective lenses made from a
combination of fluorite and quartz to improve the resolving
power. Prompted by this, H. Lehmann et al. worked on
developing a fluorescence microscope, which Zeissannounced in 1913. Reichert was quicker off the mark,having commercialized the fluorescence microscope in 191124). At first, fluorescence microscopes were mainly used toview autofluorescence (also called primary fluorescence)emitted by microbes and plant tissues. In 1933, Austrian
researcher M. Haitinger discovered fluorochromes andFig. 5.27 Nikon Transmitted Light Fluorescence
Microscope S-FS 17)

developed a fluorescent staining technique of staining certain
parts of tissues or cells with fluorochromes and viewing thesecondary fluorescence. Many types of fluorescent dyes werelater discovered, expanding the practical applications forfluorescence microscopes. In 1941, American immunologist
A. H. Coons discovered a method of staining antibodies
specifically bound to antigens with fluorochrome and thenidentifying those antigens using a fluorescence microscope.
The establishment of a fluorescent antibody technique using
fluorescein isothiocyanate (FITC) in 1950 25) led to major
breakthroughs in immunology. Thus, through thedevelopment of various fluorochromes, the fluorescenceFig. 5.28 Olympus Transmitted Light Fluorescence
Microscope FLM 4)

microscope has become an essential part of the latest medical
and biological research.

Systematic Survey on Optical Microscope Technology in Japan41

Figure 5.29 shows the optical path of a transmitted lightfluorescence microscope. Figure 5.30 shows thecharacteristics of the specimen excitation light absorption
spectrum and the accompanying fluorescence spectrum(FITC example, intensity normalized respectively). Since
fluorescence is far weaker than excitation light, an ultra-highvoltage mercury lamp is often used for illumination, as it has
a strong bright line from near ultraviolet to visible light. The
excitation light irradiating the specimen is cut from theviewing optical path using a dark field condenser so that only
the fluorescence is observed. To completely isolate theoverlap between the excitation and fluorescence spectra, an
excitation filter is placed on the illumination side to select theexcitation wavelength, while a barrier filter is placed on theviewing side to cut out any excitation light entering theoptical path and only transmit the fluorescence wavelength(Figure 5.30, thin line). The excitation filter in the figure is aninterference filter, which had just begun to be manufactured
at the time. Viewing at high magnification required oil
immersion between the objective lens and dark field
condenser and the specimen. As the immersion liquid could
not have any autofluorescence, glycerol (refractive index
1.450) was used in place of regular oil (refractive index
1.518). To cut out the excitation light in dark fieldmicroscopy, the glycerol objective lens had a built-in iris
diaphragm to lower the numerical aperture (NA) whenviewing.
Ultraviolet tester

Eyepiece

Tube

Wide field dark field condenser
Eyepiece barrier filter
Excitation filter
Objective lensUltra-high voltage
mercury lamp
Reflecting mirror

Reflecting mirror

5.7.2
Epifluorescence Microscopes
Dutch scientist J. S. Ploem (1927-) published a method of
epifluorescence illumination incorporating a dichroic mirror
to reflect short wavelength light and transmit longwavelength light in 1967 27). Shortly afterwards, Leitz
released an epifluorescence device with the brand name
Ploemopak, which had four excitation units that could beswitched easily by rotating. This epifluorescence illumination
system had many advantages over transmitted light systems.
1) Since the objective lens also served as the condenser, theNA and illumination scope of the excitation illumination
was identical to the NA and viewing scope of theobjective lens. This made for a bright, high resolution
fluorescence image with limited photobleaching(phenomenon of gradually decreasing fluorescenceintensity under excitation light).
2) Transmitted light systems used highly viscous immersion
liquids such as glycerol on the dark field condenser side
as well, making them more difficult use. Epifluorescencesystems alleviated this difficulty somewhat by only
having this on the objective lens side.
However, because the excitation light shines directly on
the objective lens in epifluorescence systems, the objective
lens must have as little autofluorescence as possible,
otherwise the background of the fluorescence image becomesbrighter and the contrast decreases. Accordingly, theobjective lens must be made from nonfluorescent glass.
To increase the brightness of the fluorescence, it ispreferable for the objective lens to have a high NA and low
chromatic aberration. Once companies overcame thesehurdles, the epifluorescence microscopes they developed
became the mainstream models that have continued to thepresent day.

Ultra-highvoltagemercury lamp

Heat absorbing
filterExcitation filter

Barrier filter

Collector lensHeat absorbing filter

Additional lens for low
magnification

Fig. 5.29 Optical Path of a Transmitted Light Fluorescence
Microscope (Nikon S-FS)(partially revised from cited reference 26)
Absorption spectrum
Fluorescence spectrum

Dichroic mirror
Collector lensAperture stop

Field stop

Excitation light
Image light (fluorescence)
Cube unit

Objective lensSpecimen

Excitation filter
Barrier filter

Fig. 5.31 Epifluorescence Microscope Structure 1)

Wavelength

Fig. 5.30 FITC Absorption/Excitation Spectra andExcitation/Barrier filter Spectrum Characteristics

42

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. MarchMercury lamp light source

Xenon light source

U excitation bright line
V excitation bright line

Wavelength

Wavelength

IY excitation bright line
G excitation bright line

BV excitation bright line B excitation bright line

Wavelength (nm)Transmittance (%)

UV excitation

V excitation

Wavelength (nm)Transmittance (%)

The following outlines the structure of epifluorescencemicroscopes, based on Figure 5.31. The epifluorescenceillumination device is placed between the base and the tube.
Light from the light source passes through the excitation filter
that selects the wavelength, is reflected by the dichroic mirror
through the objective lens to illuminate (excite) the specimen.
Fluorescence from the excited specimen passes through theobjective lens and transmits the dichroic mirror. Althoughmost of the excitation light is cut out at this point, only thefluorescence passes through the barrier filter to form thefluorescence image to be viewed or recorded. The excitation
light wavelength is selected according to the specimen andthe fluorochrome. Although ultra-high voltage mercury lamps
have been the main light source, improvements in opticalsystems and image sensor sensitivity have seen an increase in
the use of xenon lamps, which have a broader wavelength
range.

Transmittance (%)

Fig. 5.32 Ultra-High Voltage Mercury Lamp and Xenon Lamp Spectral Properties 4)

Wavelength (nm)Transmittance (%)

B excitation

G excitation

Fig. 5.33 Fluorescence Cubes 4)

Wavelength (nm)Fig. 5.34 Spectral Properties of Different Excitation Types 1)

Systematic Survey on Optical Microscope Technology in Japan43

Figure 5.32 shows the spectral properties of both lamps.
The main types of excitation include U (365nm), V (405nm),
BV (436nm), B (490nm) and G (546nm) (main excitation
wavelength shown in brackets). The excitation filters, shownby the dotted lines in the figure, combine with the dichroic
mirror and the barrier filter to form a cube unit (Figure 5.33).
These combinations can be interchanged easily, according to
the different types of excitation. Figure 5.34 shows theproperties of the different excitation filters (EX) for U, V, B
and G, the dichroic mirror (DM) and the barrier filter (BA).
Figure 5.35 shows fluorescence image photographs using U,
B and G excitation. Recent developments in interference
filter technology have made it possible to produce systems
that reflect/transmit several different wavelengths. This
makes it possible to view fluorescence from double or triple
excitation using different fluorochromes at the same time
(Figure 5.36).

(green) and barrier filter (red) 4)b) Fluorescence photomicrograph of triple
excitation filter for U (DAPI stain, cell
nucleus), B (FITC stain, microtubule) and G(TRITC stain, actin filament) 1)

The first Japanese epifluorescence microscope wasreleased by Olympus in 1973 as an attachment unit for the
Vanox (AH) (Figure 5.37). Relatively low autofluorescenceobjective lenses were used. Olympus also developed a
specialized 100× objective lens using a specially developed
silicon oil (less viscous and easier to use than glycerol) for
the immersion liquid. In 1976, Nippon Kogaku launched the
Fluophot epifluorescence microscope (Figure 5.38) with a
special CF UV-F epifluorescence objective lens (Figure
7.22d). As epifluorescence microscopes gained importance infields of research, biological microscopes with built in
epifluorescence devices began appearing in product lineups.
Figure 5.39 shows the Olympus BX63, released in 2010.

Fig. 5.37 Olympus Epifluorescence Device AH-RFL 4)

Fig. 5.35 Epifluorescence Photomicrographs Using
Different Excitation Types 1)a) U excitationb) B excitationc) G excitation

Fig. 5.38 Nikon Fluophot 17)

Fig. 5.36 a) Spectral properties of a 3-band filter for U, B
and G excitation (blue), dichroic mirror

44

Fig. 5.39 Olympus BX63 4)

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. March5.7.3

Example Applications of Fluorescence

Total internal reflection fluorescence microscopy (TIRFM)

Imaging 28) 29)
As mentioned above, as successive new fluorochromes

is a new method of fluorescence microscopy. When theincident light is shone from a medium with a high refractive

and fluorescent proteins were developed for fluorescencemicroscopes, new phenomena came into view that had neverindex to a medium with a low refractive index at an angle ofincidence greater than a critical angle, total internal reflection

been seen before. Some typical examples are given below.
1) Shimomura Osamu (1928-) discovered green fluorescentoccurs. At this time, a very small amount of light leaks to themedium on the low refractive index side at the interface; thisprotein (GFP) in the crystal jelly Aequorea Victoria in
1962 30) and identified its luminescence mechanism. GFP

is called evanescent light (or near field light). TIRFM uses
evanescent light as excitation light to excite only thedemonstrated outstanding properties in detecting specificsingle molecules when used in live cells and tissue. In

fluorescent molecules in a limited area of around 150nm on
the cover glass (or specimen surface). This allows viewing

1992, M. Chalfie (USA) introduced a GFP coded gene toE. coli and nematodes, successfully expressed GFP inwith little fluorescence from the background and high S/Nratio. Figure 5.40 shows this structure. The critical angles oflive cells. After that, GFP spread rapidly as an effective
technology for observing biological activity at molecular

total internal reflection for water (refractive index 1.33) andcells (refractive index 1.37-1.38) on a cover glass (refractive

level. Shimomura and Chalfie were awarded the Nobel
Prize in Chemistry in 2008, together with R. Y. Tsien

index 1.52) are 61° and 64.3° respectively, which equate toobjective lens NAs of 1.33 and 1.37. Since even high-end(USA), who identified the structure and mechanism of
GFP. Successive other fluorescent proteins have beenplan apochromats at 60× and 100× have a NA of 1.40, there
is very little area for total reflection. As such, a NA 1.49

discovered since, such as BFP (blue), CFP (cyan), YFP(yellow) and RFP (red).

objective lens has been developed especially for TIRFM. An
objective lens has also been developed that combines with a2) Calcium ion (Ca2+) controls various cell functions and its
dynamic state is essential to understanding biological

special high refractive index oil and cover glass to give a NAof 1.7 (see 7.4.5 (4)). A TIRFM using prism illumination

functions. In the 1960s, a method was reported ofmeasuring changes in Ca2+ by directly inserting amethod was announced in 1989, followed by thedevelopment of the special high NA objective lenses

fluorescent probe into muscle fiber. In the 1980s, many
more fluorescent probes were developed, and the method

described above, the main TIRFM system using the objective
illumination method that can be combined with other devices

became essential for visualizing the dynamic state of
Ca2+ in cells. When Fura-2, a typical fluorescent probe,and operated easily from above.

binds with Ca2+, its fluorescence intensity (510nm) undera 380nm excitation light decreases, but increases under a

Total internal reflection illumination(evanescent light)
Cover glass
Immersion oil

340nm excitation light. Measuring the fluorescenceintensity ratios makes it possible to determine the Ca2+

Objective lensconcentration. Another fluorescent probe, Indo-1, has afluorescent spectrum under a 340nm excitation light thatchanges depending on the Ca2+ concentration.
Comparing the fluorescence intensity at 480nm and
420nm determines the Ca2+ concentration. There aremany other fluorescent probes for measuring Ca2+ with
one wavelength for excitation and one wavelength forphotometry.
3) Fluorescence in situ hybridization (FISH) is a method for
determining where a particular DNA segment is in a

Field stop

Fiber
Laser

Fig. 5.40 Structure of a Total Internal Reflection
Fluorescence Microscope (inverted)(created with reference to cited reference 31)

Fluorescence microscopy has thus become an essential

chromosome. The chromosome (DNA) is fixed to a
microscope slide and reacted with a probe marked with atool for research, development and inspection in biomedicine
and other cutting-edge fields, due to various developments influorescent reagent to form a hybrid, while viewing
under fluorescence microscopy to determine the location

fluorescence probes and rapid progress in new viewing
methods, ultra-sensitive image sensors and image processing

and number of copies. Since the method was published in
1986, it has been widely used in biomedical fields forsoftware. This rapid progress in fluorescence microscopy was
aided by laser scanning microscopes, multi photon excitation

DNA mapping and detecting genetic abnormalities, as it
is a very simple method yet is highly accurate in

microscopes and super resolution microscopes, discussed in
8.1-8.3.

analysis.

Systematic Survey on Optical Microscope Technology in Japan45

References
1) Nagano C.: Kōgaku wo Chūshin to shita Kenbikyō no
Kiso [Microscope Fundamentals with a Focus on
Optics], Japan Microscope Manufacturers’ Association
website http://www.microscope.jp/knowledge/index.
html (2016.12.20), supplied by Japan Microscope
Manufacturers’ Association
2) Nagano C.: New Optical Technology Handbook, IV
Optical Equipment, 1.2 Optical Microscopes, Asakura
Publishing Co., Ltd., 2002, pp. 685-704
3) Nagano C.: Kōgakukenbikyō no Kiso to Ōyō[Foundations and Applications of Optical Microscopes],
The Japanese Journal of Medical Photography, Vol. 34
No. 2 – Vol. 35 No. 1, 1996-1997
4) Supplied by Olympus Corporation
5) Supplied by Carl Zeiss
6) Tiyoda Kenbikyō no Rekishi [History of Tiyoda
Microscopes], Sakura Seiki, 1994, pp. 83-85
7) Kubota H, Oikawa N.: Ōyō Butsuri [Applied Physics],
Vol. 18 No.6-7, pp. 163-179
8) 50-nen no Ayumi [A 50-Year History], Olympus OpticalCo., Ltd., 1969, pp. 136-138
9) Phase Contrast Microscope Symposium Bulletin, No. 1(Dec 1949), No. 2 (Jul 1950), No. 3 (Oct 1950)
10) Phase Contrast Microscope Research Society News, No.
1 (Jun 1951)
11) Tsuboi S.: Henkō Kenbikyō [Polarized Light
Microscopes], Iwanami Shoten, 1959
12) Inoue T.: New Microscopy Series 4 Ganseki Kaseki no
Kenbikyō Kansatsu [Rock and Fossil Microscopy],
Chijin Shokan, 2001
13) Basic manual for polarized light microscopes, Olympus
Optical Co., Ltd., 1995
14) Hikari to Mikuro to Tomoni - Nikon 75-nen-shi [Lightand Micro Together: A 75-year History of Nikon], 1993,
pp. 121-123
15) Takenaka H., Fujino K. & Rikukawa K.: Rectifiers,
Nikon Technical Journal, No.5, 1973, pp. 14-20
16) Tsuruta T.: Light Pencils, 25. Henkō Kenbikyō to
Rekutifaia [Polarized Light Microscopes & Rectifiers],
New Technology Communications, 1984, pp. 186-196

4617) Supplied by Nikon Corporation18) Nomarski G: US Patent No.2, 924, 142, 195219) Nojima H. (ed.): Kenbikyō no Tsukaikata Nōto
[Notebook on How to Use a Microscope], 3rd Revision,
Yodosha, Apr. 2011, p. 50
20) Lang W: Nomarski Differential Interference- Contrast
Microscopy, ZEISS Information, No.70, 1968, pp. 114120
21) Françon M. and Yamamoto T.: Optica Acta, Vol.9 No.4,
1962, p.395
22) Yamamoto T.: Journal of the Japan Society of Precision
Engineering, Vol.31 No.12, 1965, pp. 1008-1015
23) Hoffmann R and Gross L: Modulation Contrast
Microscope, Applied optics, Vol.14, 1975, pp. 11691176
24) Grundlach H: Fluorescence Microscopy: Past, Present
and Future, Royal Microscopical Society, 1997, pp. 2833
25) Coons A. H. et al.: Localization of antigen in tissue cells,
J. Exp. Med., Vol. 91 No.1, 1950, pp. 31- 37
26) Shio M.: Keikō Kenbikyō to Sono Ōyō [Fluorescence
Microscopes and Their Applications], Nikon Technical
Journal, No.2, 1973, pp. 8-23
27) Ploem J. S.: The use of a vertical illuminator withinterchangeable dichroic mirrors for fluorescencemicroscopy with incident light, Z. wiss. Mikrosk., Vol.68
No.3, Nov 1967, pp. 129-142
28) Miyawaki A.: Keikō Imējingu Kakumei [TheFluorescence Imaging Revolution], Cellular Engineering
Special Volume, Gakken Medical Shujunsha, 201029) The Photobiology Association of Japan (ed.), Funatsu T.
(ed. in charge): “Seimei Kagaku wo Hiraku Atarashii
Hikari Gijutsu [New Technologies that Blaze Trails inLife Science]”, Kyoritsu Shuppan, Dec 1999
30) Shimomura O.: Science 140, 1963, pp. 1339-1340
31) Abe K.: Keikō Kenbikyō [Fluorescence Microscopes]
VII Zen Hansha Keikō Kenbikyō [Total Reflection
Fluorescence Microscopes], in Nojima H. (ed.):Kenbikyō no Tsukaikata Nōto [Notebook on How to Usea Microscope], 3rd Revision, Yodosha, Apr. 2011, pp.
103-110National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. March

6

Development of Various Types of Microscopes

Chapter 4 discussed the birth and development of optical
microscopes in Japan with a focus on biological uprightmicroscopes. As mentioned in 2.7, there are various types of
microscopes with different forms and uses. This chapter
discusses inverted microscopes, stereomicroscopes,
educational microscopes and metallurgical microscopes(including industrial microscopes) and their development inJapan.

MSD (Figure 6.5) were this type. In 1976, Olympus launched
the IMT inverted biological microscope (Figure 6.6) and a
special long working distance objective lens, the LWDC
Plan40×.

6.1 Inverted Microscopes
As mentioned in 2.7.2, inverted microscopes are a type of
microscope in which the specimen is viewed fromunderneath, with the objective lens located under the stage.
For transmitted light systems, the light source, condenser andother parts of the illumination system are positioned above
the specimen. The first inverted microscope prototype wasmade by French optical instrument maker C. Chevalier(1804-1859) in 1834. His compatriot, French chemist H. Le
Chatélier (1850-1936, known for his chemical equilibrium
principle) used an inverted microscope to observe metal
specimens face down, after which inverted metallurgicalmicroscopes also became known as Chatélier microscopes.
Later, inverted microscopes spread in popularity, mainly forobserving metal specimens. Eventually, with the emergenceof phase contrast microscopes and as people started studying
culture cells, inverted biological microscopes became more
popular, as it was easier to view cells at the bottom of theculture fluid on a fixed stage. This section discusses thedevelopment of inverted biological microscopes that are now
the main type used in bio research and inspection. Inverted
metallurgical microscopes are discussed in 6.4.2.
The first inverted biological microscope in Japan was the
PMB (Figure 6.1), produced by Olympus in 1958, based on
an inverted universal metallurgical microscope andincorporating a trans-illumination system. In 1964, Nippon
Kogaku developed the MD (Figure 6.2), a dedicated inverted
biological microscope, in collaboration with the University ofTokyo Institute of Medical Science 2). This had a sideport,
which allowed greater systematicity, while the fixed stage
and moving objective lens focusing mechanism eliminatedany timewise focal loss, which made it possible to performtime lapse filming. This was a trailblazing inverted biologicalresearch microscope, fully equipped with all the
specifications needed for cell research at the time. In 1967,
the MD was systemized into the multipurpose Model M,
which could be used for biological or metallurgicalmicroscopy, or both. Tiyoda launched its T-2 inverted
microscope (Figure 6.3) in 1965. As the study of culture cells
became more widespread, a succession of simpler inverted
microscopes called culture microscopes emerged, starting in
1966. The Olympus CK (Figure 6.4) and Nippon Kogaku

Fig. 6.1 Olympus PMB 1)

Fig. 6.2 Nikon MD 3)

Fig. 6.3 Tiyoda T-2 4)

Fig. 6.4 Olympus CK 1)

Fig. 6.5 Nippon Kogaku
MSD 3)

Fig. 6.6 Olympus IMT 1)

Systematic Survey on Optical Microscope Technology in Japan47

As discussed in 4.6, Japanese upright microscopes
underwent a complete redesign of the objective lens and otherparts of the optical system from the late 1970s, resulting in
new microscope performance, function and design. New
inverted microscopes were also launched as a result. In 1976,
Nippon Kogaku introduced the CF optical system to themarket. The company launched the Diaphot TMD inverted
biological microscope in 1980 (Figure 6.7), followed by the
TMS culture microscope in 1984. The TMD was highly
regarded for its superior optical performance, its consistencyof form and the diversity of its system, which included
epifluorescence and differential interference contrast. The
model took an increasing share of the bioresearch domain,
both in Japan and overseas. In 1978, Olympus released the
new LB optical system, followed by the IMT2 (Figure 6.8)
and CK2 (Figure 6.9) microscopes in 1984. In 1993, Nikon
launched the TMD300 (Figure 6.10), an improved version of
the Diaphot. In 1994, Olympus switched to a new infinity
corrected optical system and released the IX50 and IX70
(Figure 6.11) inverted biological microscopes with the UIS
optical system. Nikon responded with the launch of the
Eclipse TE300 in 1997 (Figure 6.12), featuring the CFI60
optical system. Nikon later released the Eclipse Ti-E in 2007
(Figure 6.13), while Olympus launched the IX2 series in2002 and the IX3 series (Figure 6.14) in 2012, each model
progressing in response to the latest needs in the field.

Fig. 6.9 Olympus CK2 1)

Fig. 6.10 Nikon TMD300 3)

Fig. 6.11 Olympus IX70 1)

Fig. 6.12 Nikon TE300 3)

Fig. 6.13 Nikon Ti-E 3)

Fig. 6.7 Nikon TMD 3)

Fig. 6.14 Olympus IX83 1)

Fig. 6.8 Olympus IMT2 1)

48

One important application for inverted microscopes isinfertility treatment. Unlike artificial insemination, in which
active sperm are selected and placed artificially into theuterus to aid impregnation, in vitro fertilization (IVF)
involves extracting eggs that have grown to near ovulation(ovum collection), fertilizing them with sperm and thenplacing them back in the uterus once they have undergone
cell division (embryo transfer). Following the birth of thefirst child conceived by in vitro fertilization in the United
Kingdom in 1978, the process spread rapidly around theworld. In Japan, around 40,000 babies are born each year
through IVF. Intra-cytoplasmic sperm injection (ICSI)National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. Marchinvolves injecting a sperm directly into an extracted egg
under microscope. The process was first performed in 1992
(using a Nikon TMD). Figure 6.15 shows an example
inverted microscope fitted with a micromanipulator. Figure
6.16 shows a sperm being injected into a human embryo. In
1996, Dolly, the cloned sheep, was born in the United
Kingdom in 1996 (announced in 1997). The process involved
taking the nucleus of a somatic cell from a sheep, transferring
it into the enucleated unfertilized germ cell of another sheep
and, following cell fusion, placing the embryo into the uterus
of a surrogate mother ewe (a Nikon TMD was used).
Although cloning technology has since been used on larger
mammals, such as cattle and horses, Japan announced in2000 that human cloning technology would be prohibited bylaw.

Fig. 6.15 Olympus IX71 + Manipulation System 1)

Fig. 6.16 Injecting a Sperm into a Human Embryo 5)(1801-1875)) in 1893. The company replaced the relay lenswith this system to produce a compact prototype of themodern stereomicroscope (1897) and marketed it as theGreenough microscope (Figure 6.17).
Takachiho produced Japan’s first stereomicroscope, the
XA, in 1933 (Figure 6.18) 3). It had three objective lenses anda maximum total magnification of 48×, as well as a hand restfor easier operation. Nippon Kogaku launched its firststereomicroscope, the SM, in 1954 (Figure 6.19). Equippedwith a three-level magnification system of the Galileo
telescope type (combination of convex and concave lenses)
and designed to prevent loss of focus while changing
magnification, the microscope also had an epi-illumination
device. Olympus released its X model (Figure 6.20) withsimilar specifications in 1959.

Fig. 6.17 Zeiss Stereomicroscope (1897) 6)

Fig. 6.18 Olympus XA 1) 7)

6.2 Stereomicroscopes
Stereomicroscopes are microscopes with two separate
optical axes from the specimen to the left and right eye. The
parallax caused by the angle between the optical axes createsa stereoscopic view. Since it is used for tasks such as
inspection and dissection, the viewing image must be an erect
image with the same orientation as the specimen. American
biologist H. S. Greenough devised a method for stereoscopic
viewing of an erect image and took it to Zeiss. His idea wasto have an objective lens on each optical axis as well as arelay lens to erect the respective images. However, Zeiss had
already made binoculars using the Porro prism (an erecting
prism invented by Italian optical instrument inventor I. PorroFig. 6.19 Nippon Kogaku SM 3)

Systematic Survey on Optical Microscope Technology in Japan49

Fig. 6.20 Olympus X 1)

In 1957, American Optical launched a stereomicroscope
under the brand name Cycloptic. It had two parallel opticalaxes from the objective lens and a variable magnification
optical system (five levels ranging from 0.7× to 2.5×, byrotating two Galileo telescopes). In contrast to the Greenough(convergent) system, this arrangement is called the common
main objective (CMO) system or parallel optical axis system.
This stereomicroscope was rapidly adopted, particularly foruse in the fledgling semiconductor manufacturing process.
Two years later in 1959, rival American company Bausch &Lomb brought out its own stereomicroscope under the brandname StereoZoom, with a Greenough system and aconsecutive zoom mechanism. The objective lens had amagnification range of 0.7-3× (zoom ratio of 4.3), while theerect image was produced by an arrangement of fourreflecting mirrors in the tube. As this system was able to keep
up with current needs, such as providing moreinterchangeable lenses, an illumination system, an arm, astand etc., it was well received in the semiconductor industry
and other industrial fields, as well as in biology andmedicine. Production and sales continued for more than 40
years until 1990, when Bausch & Lomb merged with the
Leica Group, along with other companies, including
American Optical.
Japanese stereomicroscopes adapted early to zoom
capabilities. While zoom lenses had been used in TV cameras
and small-scale video cameras that did not need highresolution, in 1959, Nippon Kogaku brought out the Nikkor
Zoom 8.5-2.5cm for use in the Nikon F single-lens-reflex(SLR) camera. This demonstrated the high standard of opticaldesign technology at the time. This was developed for use asa stereomicroscope zoom lens and went on the market in1961 in the SMZ (Figure 6.21). The magnification was 0.84× (zoom ratio of 5). Meanwhile, Olympus had made its own
progress on stereomicroscope zoom lenses, having pioneered
camera lenses, and unveiled the SZ (Figure 6.22), Japan’s
first stereomicroscope with zoom capability, in 1960. The
microscope was released onto the market in 1961, the same
year as the SMZ. In 1966, the SZ was the first Japanese
microscope to be awarded the Good Design Award(inaugurated in 1957 by the Ministry of International Tradeand Industry, symbolized by the “G Mark” system). Both ofthese models were easier to use than the existing stepped
magnification system and many were adopted into assembly
processes in electronics industries such as precision
technology and semiconductors. The microscopes were also
widely adopted in biomedical research and other fields andhave since proven to be long sellers. The SMZ is still being
manufactured and sold today, more than 50 years after it was

50

launched. In 2011, it was awarded the Good Design Long
Life Design Award. The convergent (Greenough) system has
continued to the present day in popular model
stereomicroscopes, manufactured and exported by Olympus
and Nikon, as well as mid-sized microscope manufacturers
such as Meiji Techno (formerly Meiji Labax), Carton
Optical, Kyowa Optical, Seiwa Optical, Minato Optical,
Optart and Nissho Optical. Since around the turn of the
century, an increasing number of microscopes have been
fitted with white LED illumination for energy conservationand longevity.

Fig. 6.21 Nikon SMZ 3)

Fig. 6.22 Olympus SZ 1)

With growing demand for stereomicroscopes to havehigher magnification and resolution for applications, such as
integrating semiconductors and handling tissue cells, thelimitations of the Greenough system started becoming more
apparent. Drawbacks included difficulty in correcting opticalaberration due to the optical axis biasing towards the
specimen and difficulty in adding various units into the
middle of the optical system. These were proving to be major
limitations to its systematization. To resolve these issues, asingle-objective, parallel optical path system wasreconsidered. The first dedicated single-objective
stereomicroscope in Japan was the SMZ-10 (Figure 6.23),
released by Nippon Kogaku in 1977. The objective lenses
had a magnification of 0.66-4× (zoom ratio of 6). Bychanging the objective lens and the eyepiece, the total
magnification was 3.5-160×. Various illumination systems,
including epi-illumination using the same axis, andaccessories such as a stand were added to the line up to meetthe needs of stereomicroscope users in the research market.
Although the global market for high-end stereomicroscopes
was dominated by Swiss company Wild (later Wild Leitz,
now Leica Group), the SMZ-10 was the forerunner of highend Japanese stereomicroscopes. By way of competition,
Olympus brought out the SZH high-end stereomicroscope in1985 (Figure 6.24). The objective lens had a high zoom ratioof 8.5, with magnification of 0.7-6× (total magnification of
3.5-360×). The single objective lens maintained high optical
performance by taking measures to prevent image distortion
from the large decentralized optical system and incorporating
technology such as semi apochromatic lenses to prevent
chromatic aberration.

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. MarchFig. 6.23 Nikon SMZ-10 3)

Fig. 6.24 Olympus SZH 1)

It was a high-end system that included many accessories aswell. In 1990, Nikon released the SMZ-U stereomicroscope
system (Figure 6.25) with a zoom ratio of 10 (0.75-7.5×
objective lens, 3.75-450× total magnification). After that,
Olympus brought out the SZH10 with a zoom ratio of 10(0.7-7×), followed by other products with even higher zoom
ratios, such as the SZX12 (0.7-9×, zoom ratio of 12.86,
Figure 6.26) and the SZX16 (0.7-11.5×, zoom ratio of 16.5,
Figure 6.27). Following the SMZ800 in 1999, Nikon alsobrought out the SMZ1000 and SMZ1500 (0.75-11.25×, zoom
ratio of 15, Figure 6.28), and then the SMZ25 in 2013 (0.6315.75×, zoom ratio of 25, Figure 6.29, combined with theepifluorescence set). Throughout this time, both companies
were also producing additional accessories such as
epifluorescence units, revolving nosepieces for changing
objective lenses, variable tilt tubes and electronic focusing
devices, as well as steadily building up their optical
performance by changing over to apochromatic lenses andhigher resolution (currently, the highest NA in the world for astereomicroscope is 0.312).

Fig. 6.28 Nikon SMZ1500 3)

Fig. 6.29 Nikon SMZ25 3)

As a result of Olympus and Nikon working together todevelop products with higher specifications and better
performance, Japanese products now lead the world also in
the area of stereomicroscopes.

6.3 Educational Microscopes
There is no clear definition of educational microscopes.
They are usually microscopes that are used for scienceeducation in elementary and secondary schools. Thesemicroscopes are equipped with the minimum required
functions and performance, are robust, durable andmoderately priced. In elementary school, children start using
microscopes in their science classes from 5th grade. The next
step up, used by university science and medical students, arecalled student microscopes and are outside the scope of thischapter. Japan’s first specifically educational microscope was
the Sakura (Figure 6.30), produced by Takachiho Optical in1922 at the request of a scientific instruments dealer in Kyoto
for a simple microscope to use in elementary and secondary
schools. Modelled on a German-made student microscope, it
only had one objective lens. It was later developed into the
Hatsukaze on an ST model.

Fig. 6.25 Nikon SMZ-U 3)

Fig. 6.30 Olympus Sakura 1)

Fig. 6.26 Olympus SZH12 1) Fig. 6.27 Olympus SZH16 1)

Systematic Survey on Optical Microscope Technology in Japan51

After the war, with the view that science education would
play an important part in laying the foundation for a cultural
nation, the Japanese government established the Science
Education Promotion Act in 1953 and executed it thefollowing year. Japan Industrial Standards also began to be
formulated for microscopes, with JIS B 7132 Biologicalmicroscopes enacted in 1949, followed by 7133 Biologicalmicroscopes for dry objectives, 7134 Small size biologicalmicroscopes, 7139 Stereo microscopes etc. in 1951 (seeAppendix 1). As this took place, microscope manufacturers
focused their efforts on developing educational microscopes
based on these JIS standards. Olympus released the MK(MIC) low-cost, simple microscope in 1959 (Figure 6.31),
aimed also at ordinary household use. With objective lenses
able to be changed by turning a handle, it had four
magnification levels and a total magnification of 40-300×.
Designed for ease of use, the tube was tilted at 30° andfocusing was performed by moving the stage up and down. In
1960, this microscope was designated by both the JIS and theScience Education Promotion Act. The same year, theMicroscope Observation Contest started by Olympus incollaboration with children’s newspaper Mainichi Shogakusei
Shimbun changed its name to the Natural Science
Observation Contest (Shizecon). To this day, the contest
continues to contribute to promoting science education forschoolchildren. Kalnew Optical released the SGL-600
educational microscope in 1960 (Figure 6.32), the year after
it became an affiliated company of Shimadzu. Developedwith guidance from Tokyo University of Education (now the
University of Tsukuba), the microscope was fully designed
for children, including its overall size, the viewing angle andthe up and down movement of the stage, making it theexemplary educational microscope of the day. The same year,
Nippon Kogaku also launched an educational microscope, theE model (Figure 6.33, E stands for Elementary). Based on the
S research microscope and designed for science classes, thismicroscope was packed away into a unique rocket shell shapestorage box to make it easy for children to handle. As otherJapanese microscope manufacturers also began bringing out
their own educational microscopes, the major companies
stopped investing in new products for this market. This
allowed major educational equipment companies such as
Uchida Yoko and Shimadzu Rika to dominate this area.
Recent changes have been seen with ICT entering the scienceclassroom, such as microscopes with digital displays (Figure6.34 shows a microscope with a digital display, released in2014) and improved educational software.

Japan has always aimed to be a nation of science andtechnology. Microscopes that focus on science education are
an important educational tool and a first step in getting
children interested in science. Microscopes make it possible
for children to enjoy their learning as they observe the microworld with their own eyes. With more microscopes in thismarket now being imported from China and other emerging
nations, the hope is that the mid-sized Japanesemanufacturers will still hold their ground in this country, themicroscope superpower.

Fig. 6.33 Nippon Kogaku E 3) Fig. 6.34 Uchida D-EL4N 9)

6.4 Metallurgical (Industrial) Microscopes
6.4.1

Reflected Light (Incident Light, EpiIllumination) Microscopy 10)
Thus far, we have discussed microscopy of biological
specimens by transmitted light illumination or fluorescence.
For viewing specimens made of metal or ceramic material
that do not transmit light, reflected light illumination is used.
Figure 6.35 shows an illumination optical system for standard
reflected light microscopy. Light from the light source isreflected off the half mirror and illuminates the specimen
through the objective lens. The light reflected from thespecimen passes through the objective lens and is transmitted
by the half mirror to form an image. Dark field anddifferential interference contrast are also often used inreflected light microscopy.
Primary
image

Imaging lensCollector lensHalf mirror
Light source

Aperture stop

Field stop

Light path showing the imaging
relationship of the specimen

Fig. 6.31 Olympus MK(MIC) 1)52

Fig. 6.32 Shimadzu Kalnew
SGL-600 8)

Objective
lensLight path showing the imaging
relationship of the light source

Specimen

Fig. 6.35 Reflected Bright Field Optical System 10)

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. MarchFigure 6.36 shows a reflected dark field optical system. The
incident light forms a ring through the aperture and isreflected by a mirror with a hole. The light travelling along
the illumination optical path through around the dark fieldobjective lens illuminates the specimen by means of a ringshaped lens or mirror. The image is formed by only the lightscattered or diffracted by the specimen passing through theobjective lens. Any small flaws or level differences stand out
as visible by sparkling, making this very effective forinspecting the surface of the specimen. Figure 6.37 shows areflected differential interference contrast optical system.
Light from the light source is linearly polarized by thepolarizer on the illumination optical path and then reflectedby the half mirror to the Nomarski prism, which divides it
into two linearly polarized light rays vibrating at right angles
to each other that illuminate the specimen at a separation(shearing value) lower than the resolving power. The twolinearly polarized light rays reflected by the specimen are
combined once more by the Nomarski prism. After passing
through the analyzer, a contrast image is obtained that
corresponds to the differential coefficient of the level
difference (phase contrast) of the specimen with interference.
The contrast, including sensitive color, can also be adjusted
by moving the prism horizontally. Since reflected differential
interference contrast makes it possible to detect minuteirregularities that could not be detected under reflected brightfield microscopy, it is widely used in inspection processes.
Mirror with
hole

Ring
stop

Dark field objective
lensFigure 6.38 shows the same view of an integrated circuitunder reflected bright field, reflected dark field and reflecteddifferential interference contrast microscopy.
6.4.2

History and Development of Metallurgical(Industrial) Microscopes
French chemist and mathematician F. de Réaumur (16831757) made observations of the surface structure of fracturesin iron under microscope and published “L’Art de Convertir
le Fer Forgé en Acier [The Art of Converting Forged Iron
into Steel]” in 1722. German physician J. N. Lieberkühn(1711-1756) fitted a concave mirror (called a Lieberkühn
mirror) to a microscope to perform animal dissections underreflected light (Figure 6.39). British geologist H. C. Sorby(see 5.4) used a microscope fitted with a special reflected
illumination system to examine microstructures. He
published his findings on the crystalline structure of minerals
in 1858 and on the structure of iron and steel in 1863. After
that, the United Kingdom began to produce many
metallurgical microscopes. Specimens view undermetallurgical microscopes are often larger and heavier thanthose view under biological microscopes. The surface of thespecimen also needs to be perpendicular to the viewing
optical axis. To resolve these issues, the inverted
metallurgical microscope (Chatélier microscope) was
devised, with a fixed stage and the specimen observed fromunderneath (see 6.1). This has a coaxial system in which theobjective lens itself serves as the condenser lens to allow theincident light to illuminate the specimen perpendicularly.
There are two ways to achieve this: using a thin plate, as
shown in Figure 6.40 a), or using a prism, as shown in Figure6.40 b).

Specimen

Fig. 6.36 Reflected Dark Field Microscopy 10)
Polarizer

Analyzer
Half mirror

Nomarskiprism

Fig. 6.39 Lieberkühn Mirror Reflected Illumination(created with reference to cited reference 11)

ObjectivelensSpecimen

Fig. 6.37 Reflected Differential Interference Contrast
Microscopy 10)

Fig. 6.38 Photographs of an Integrated Circuit under
Reflected Light Microscopy 10)a) Bright Fieldb) Dark Fieldc) Differential Interference
Contrast

Fig. 6.40 Reflected Illuminationa) Thin Plate Methodb) Prism Method(created with reference to cited reference 11)

Systematic Survey on Optical Microscope Technology in Japan53

At first, semi-transmissive mirrors were difficult tomanufacture, so the thin plate method only resulted in dark
images, as much of the illumination light was lost. While theprism afforded brighter illumination through total reflection,
the resolving power was lower, as half of the objective lens
aperture was hidden, resulting in uneven image brightness
and lateral shift during focusing. Ultimately, once it became
possible to produce uncolored semi-transmissive mirrors, thethin plate method took precedence. There are two ways inreflected dark field illumination to have the light passing
around the objective to illuminate the specimen: using a ringshaped concave mirror, as shown in Figure 6.41 a), or using aring-shaped lens, as shown in Figure 6.41 b). This prototype,
Ultrapak, made by Leitz, was originally made for biologicaluse, but was also used in metallurgical microscopes as well.

After the war, the first company to establish itself in
metallurgical microscopes was Union Optical (referred to
below as Union, the company went insolvent in 2010),
founded in 1948. The company launched the UM inverted
metallurgical microscope (Figure 6.44 shows the NUM, an
improved version of the UM) in 1952. This was followed bya succession of small to medium metallurgical microscopes,
including the MeC, and the company emerged as a prominent
national metallurgical microscope manufacturer 14).
Meanwhile, Olympus brought out the PMF universal inverted
metallurgical microscope in 1954 (Figure 6.45). This
microscope shifted away from the horizontal design with a
new vertical style. The photomicrographic equipment wasalso compact and easier to use, having switched from thelarger dry plates to 35mm film. Capable of reflected lightphase contrast and polarized light microscopy, this truly was
the pinnacle of Japanese metallurgical microscopes at thetime. Olympus released the MF in 1959 (Figure 6.46), which
would become the benchmark standard for uprightmetallurgical microscopes. In 1964, the company further
developed the PMF to produce the PMG (Figure 6.47), thehigh-end universal inverted microscope with an inbuilt
photometer for photomicrography. In 1967, the company also
launched the Neopak MN bright/dark field metallurgicalmicroscope (Figure 6.48).

Fig. 6.41 Reflected Dark Field Illuminationa) Concave Mirror Methodb) Lens Method(created with reference to cited reference 11)

Japanese development of metallurgical microscopes beganwith Takachiho Works in 1928, with a subsidy from the
Ministry of Commerce and Industry. Developers studied themetallurgical microscopes made by Reichert, the most
reputable in the world at the time, and completed the
Olympus MC in 1930 (Figure 6.42) 12). The company also
developed the PMA photomicrograph apparatus (Figure 6.43)
for inverted metallurgical microscopes. This was a horizontal
device, like many photomicrographic devices at the time. In
1938, the company developed the Super Photo “Universal”(Figure 4.10), equipped for reflected light and transmitted
light bright-field/dark-field observation and with built in
devices for photography.

Fig. 6.42 Olympus Metallurgical Microscope MC 13)

54

Fig. 6.43 Olympus Inverted Metallurgical Microscope
Photomicrograph Apparatus PMA 13)

Fig. 6.44 Union Universal Inverted Microscope NUM 15)

Fig. 6.45 Olympus Universal Inverted Microscope PMF 1)

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. MarchUnion announced the UPM universal upright microscopearound 1967 (Figure 6.49). This and other high-end models
for reflected/transmitted bright field illumination, as well asphase contrast, interference, polarized light and dark field
illumination, led the company to dominate the Japanese
metallurgical microscope market alongside Olympus. Nippon
Kogaku added a reflected light illumination system to its S
biological microscope system for research and stepped into
the arena with the S-M upright metallurgical microscope in1961 (Figure 6.50). In 1964, the company brought out the
ME inverted metallurgical microscope.

Fig. 6.46 Olympus Metallurgical Microscope MF 1)

Metallurgical microscopes were also developed as optical
instruments for inspecting and measuring precision parts invarious industrial fields. Relatively simple versions aretoolmakers’ microscopes and factory microscopes. Nippon
Kogaku pioneered this field in Japan, developing various
measuring instruments for its own use as inspection tools
from 1920. With the Second Sino-Japanese War making it
difficult to import measuring instruments from the West, thecompany answered the call of the nation and in 1938 began
supplying others with many kinds of optical instruments 16).
In 1939, the No. 1 universal projector (also called ameasuring projector or profile projector) (Figure 6.51) wascompleted. After the war, as the manufacturing industry
advanced, various manufacturers started putting out thesekinds of measuring microscopes in full force. Typical models
include the SM factory microscope (Figure 6.52), released byUnion in 1955, and the MTM large moiré fringes toolmakers’
microscope (Figure 6.53). These are optical instruments thatuse microscope technology. The developments in measuringmethods and advances in technology and company products
are very interesting. However, no further detail is given here,
as the topic of this report is optical microscopes.
As mentioned in 5.5, Nippon Kogaku released the
Yamamoto-Françon type S-R reflected light differential
interference contrast microscope in 1966 (Figure 5.22b).

Fig. 6.47 Olympus Universal Inverted Microscope PMG 1)

Fig. 6.50 Nikon
Fig. 6.51 Nippon Kogaku
Metallurgical
Universal
Microscope SMicroscope No. 1 16)
3)
M

Fig. 6.48 Olympus Bright/Dark Field Metallurgical
Microscope Neopak MN 1)

Fig. 6.52 Union Factory Microscope SM 15)
Fig. 6.49 Union Universal Upright Microscope UPM

14)

Systematic Survey on Optical Microscope Technology in Japan55

Fig. 6.53 Olympus Large Toolmakers’ Microscope MTM 1)

Union developed a Nomarski type reflected light differential
interference contrast system and launched it in the form of
the ME-IC in 1971 (Figure 6.54) 17). Olympus sublicensed theNomarski patent from Union and added the M-NIC incident
differential interference contrast unit (Figure 6.55) to its
lineup in 1973 for use in the MF and universal AHM
microscopes. Nippon Kogaku went for a long time without
putting out any new industrial microscopes except for an IC
inspection microscope in 1974. In 1976, the company
launched the Metaphot metallurgical/industrial microscope(Figure 6.57) at the same time as the new CF optical system.
This was followed by the Optiphot XP industrial microscopein 1978 and the Optiphot-55 IC inspection microscope thefollowing year (Figure 6.58).

The company strengthened its assault on the industrial
microscope market by responding to market needs, such as
better optical performance, dark field and differential
interference contrast (using the Nomarski system) capabilities
and adding a large stage for handling wafers (the 55 in thename of the microscope stands for the stage size of 5″×5″).
Olympus responded by developing the new infinity
correction (IC) series of lenses for industrial microscopes(see 7.4.3). The lenses were launched in 1981 with the BH2UMA universal reflected light microscope (Figure 6.59),
capable of switching easily between bright field, dark field,
polarized light and differential interference contrast. The
following year, Nikon launched the Optistation wafer
inspection microscope device (Figure 6.60), mainly used forvisual inspection during the lithography and etchingprocesses in semiconductor manufacturing. This vastly
increased the industrial microscope’s share of thesemiconductor manufacturing industry. Both companies
continued to bring out new innovations, such as more typesof objective lenses, larger stages to match larger sizes ofliquid crystals and wafers (Nikon brought out the Optiphot88 in 1987), and automating various operations.

Fig. 6.57 Nikon Metaphot 3)

Fig. 6.54 Union ME-IC 15)

Fig. 6.55 Olympus M-NIC 1)

Later, as the market for metallurgical microscopes
expanded, metallurgical microscopes other than inverted
microscopes began to be known as industrial microscopes, as
it was becoming common to use them for applications otherthan examining metal specimens. The Olympus BHM
industrial microscope (Figure 6.56), launched in 1975 basedon the high-end BH microscope system, became thebenchmark standard.

Fig. 6.56 Olympus BHM (optical path diagram) 1)

56

Fig. 6.58 Nikon Optiphot-55 3)

Fig. 6.59 Olympus BH2M (optical path diagram) 1)

Fig. 6.60 Nikon Optistation 15)

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. March

In 1993, Olympus brought out the new UIS infinity
corrected mechanical tube length optical system forbiological microscopes. The following year, the company
launched the UIS optical system for industrial microscopes,
together with the BX60M industrial microscope (Figure6.61). The year after that, Olympus launched the MX50
semiconductor inspection microscope (Figure 6.62), which
had a large stage capable of holding 6″ and 8″ wafers, and theMX40 ordinary class industrial inspection microscope. The
MX50 had improved operability, such as a variable tilt tube
(0-35°). The MX80 (Figure 6.63) could be extended toinspect a 300mm wafer, photo mask or flat panel display(FPD).

It also had more automated and electronic functions, such as
auto focus. Nikon responded by incorporating the CF & IC
series developed in 1994 into the Optiphot 100S
metallurgical and LSI inspection microscope (Figure 6.64). In
2000, the company launched the Eclipse L200 LSI inspection
microscope, with the newly developed CFI60 optical system
built in and capable of handling 200mm wafers. The
company also put out the L200A the same year (Figure 6.65),
with more automated functions and greater system
scalability. In 2001, Nikon released the Eclipse L150 and
L150A industrial microscopes capable of handling 150mm
wafers. These were followed by the Eclipse L300D FPD
inspection microscope in 2004 (Figure 6.66), capable ofhandling a 400mm × 300mm sample size. In 2005, thecompany followed with the Eclipse LV150 industrial
microscope (Figure 6.67), successor to the Optiphot 100S,
and the 100 series.

Fig. 6.61 Olympus BX60M 1)
Fig. 6.64 Nikon Optiphot 100S 3)

Fig. 6.62 Olympus MX50 1)
Fig. 6.65 Nikon Eclipse L200A 3)

Fig. 6.63 Olympus MX80 1)
Fig. 6.66 Nikon Eclipse L300D 3)

Systematic Survey on Optical Microscope Technology in Japan57

Union incorporated its new SPLM series infinity corrected
optical system into the Versamet-3 high-end inverted
metallurgical microscope, launched in 1990 (Figure 6.71).

Fig. 6.67 Nikon Eclipse LV150A 3)

Despite the emergence of a new optical system in the late1970s, new models of inverted metallurgical microscopes
were slower to be developed than upright/inverted biologicalmicroscopes or upright metallurgical microscopes. Nippon
Kogaku launched its first inverted metallurgical microscope,
the Epiphot TME, in 1981 (Figure 6.68). Until then, Olympus
and Union had dominated the Japanese inverted metallurgicalmicroscope arena. However, the high performance of the CF
optical system and the robust design were well regarded byusers. Olympus brought out the IC series infinity corrected
optical system in 1981 and launched the PMG3 high-end
inverted metallurgical microscope in 1987 (Figure 6.69).
Inverting the previous reverse image and incorporating azoom mechanism, this was a drastically improved designfrom the PMG2 high-end universal microscope released in1972. The IC optical system also offered improved
performance and was well received by many users. The
following year, the company also launched the popular PME3
(Figure 6.70).

Fig. 6.70 Olympus PME3 1)

Fig. 6.71 Union Versamet-3 14)

Nikon launched the TME300 universal research
microscope (Figure 6.72) and the TME200 as successors to
the TME from 1995, using the CF & IC optical system. In
2006, the company released the Eclipse MA100 popular
inverted metallurgical microscope using the new CFI60
optical system. This was followed by the MA200 in 2008
(Figure 6.73), with a new box design. These microscopemodels have continued to the present day.

Fig. 6.68 Nikon Epiphot TME 3)

Fig. 6.72 Nikon Epiphot TME300 3)

Fig. 6.69 Olympus PMG3 1)

58

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. MarchOlympus launched the GX71 high-end system inverted
metallurgical microscope (Figure 6.74) and the GX51
metallurgical microscope system, using the industrial UIS
optical system introduced in 1994. The company also
launched the GX41 small-scale inverted metallurgicalmicroscope in 1994 (Figure 6.75). All new products since2000 have changed from the 35mm camera and large size infavor of digital systems. This has the advantage of improved
performance and operability.

Fig. 6.73 Nikon Eclipse MA200 3)

Fig. 6.74 Olympus GX71 1)

References

1) Supplied by Olympus Corporation
2) Kato J.: Seibutsu-yō Tōritsu Kenbikyō [Inverted
Biological Microscopes], Nikon Technical Journal, No.
9, 1974, pp. 6-20
3) Supplied by Nikon Corporation
4) Tiyoda Kenbikyō no Rekishi [History of Tiyoda
Microscopes], Sakura Seiki, 1994, p. 98
5) Nagano C.: Kōgakukenbikyō no Kiso to Ōyō[Foundations and Applications of Optical Microscopes],
The Japanese Journal of Medical Photography, Vol. 35
No. 1, 1997, pp. 2-7
6) Supplied by Carl Zeiss
7) Olympus Microscope catalog, Takachiho Works Co.,
Ltd., 1934, p. 138) Supplied by Shimadzu Rika Corporation
9) Supplied by Uchida Yoko Co., Ltd.
10) Nagano C.: Kōgaku wo Chūshin to shita Kenbikyō no
Kiso [Microscope Fundamentals with a Focus on
Optics], Japan Microscope Manufacturers’ Association
website http://www.microscope.jp/knowledge/index.
html (2016.12.20), supplied by Japan Microscope
Manufacturers’ Association
11) Mütze K. et al.: ABC DER OPTIK, Verlag Werner
Dausien, 1961, pp.561-562
12) 50-nen no Ayumi [A 50-Year History], Olympus OpticalCo., Ltd., 1969, pp. 46-49
13) Kusetsu jūsan-nen Orinpasu Kenbikyō/Gentō-ki/Eisha-ki
no Keireki [Thirteen Hard Years: The Career History of
Olympus Microscopes, Slides and Projectors], TakachihoWorks Co., Ltd., 193214) 20-Nen no Ayumi [A 20-year History], Union OpticalCo., Ltd., 1968
15) Union Optical product catalog16) Hikari to Mikuro to Tomoni - Nikon 75-nen-shi [Lightand Micro Together: A 75-year History of Nikon], 1993,
p. 85, p. 375
17) Kikuchi Y.: Kanshō Kontorasuto [Interference Contrast]
ME-IC, Ryokosha Technical Bulletin, Vol. 8 No. 90,
1971

Fig. 6.75 Olympus GX41 1)

Systematic Survey on Optical Microscope Technology in Japan59

7

Development of Optical Technology for
Microscopes

Technological components of microscopes include opticalsystems, mechanical systems, electrical/electronic systems
and software. Of these, it is the optical system that mostdetermines microscope performance. This chapter discusses
the history and development of the optical system,
particularly the central component at the heart of the
microscope: the objective lens. This is also the author’s fieldof expertise.

7.1 History of Objective Lenses 1)
7.1.1
Advances in Basic Performance
As discussed in 3.2, following the invention of thecompound microscope around 1600, the objective lenses usedin microscopes were single lenses (Figures 3.1, 3.2) until theinvention of achromatic lenses. These single lenses were notcapable of high magnification. Even after the successful
manufacture of achromatic lenses by Dollond in 1758, as
mentioned in 3.3, no high magnification objective lenses
were immediately forthcoming that were capable ofsatisfactorily eliminating the spherical aberration caused byincreasing the numerical aperture. This was resolved by
Lister in 1830. Figure 7.1 shows how a virtual image O′ of an
object O is created by plano-convex achromatic lens A, after
which a real image of O′ is created by plano-convex
achromatic lens B. This made it possible to manufacture
objective lenses with relatively high numerical aperture andlow spherical and chromatic aberration.
In 1837, Amici added a hemispherical lens on the object
side of Lister’s objective lens to successfully produce a highNA, high-magnification objective lens that corrected
spherical and chromatic aberration (Figure 7.2). On theunderstanding that increasing the numerical aperture would
increase the resolving power, he also came up with the ideaof immersion lenses, in which the space between thespecimen and the apex of the objective lens is filled withliquid to increase the numerical aperture. He successfullycompleted the first water-immersion objective lens in 1853.

Although these gradual improvements were being made to
microscope objective lenses, it was Abbe (Figure 3.6) who
transformed Zeiss into a top microscope manufacturer. Fromthe 1870s, he established microscope image formation theory,came up with designs by objective lens ray tracing and set up
testing systems in the manufacturing process. Lens design by
ray tracing was practiced in part at the start of the 18th
century and is still used today. In 1819, J. Fraunhofer (17871826) designed a large-diameter (φ244mm) refracting
telescope objective lens using glass data (refractive index anddispersion properties). In 1870, Abbe adopted this method ofdesign for microscope objective lenses and found a way ofcorrecting comatic aberration by meeting the sine condition(the ratio of NA between the object side and image side isconstant in whole NA and equal to the magnification value).
Using this method, he completed designs for a series ofobjective lenses, correcting spherical aberration and meetingthe sine condition (aplanat), as well as correcting chromaticaberration (achromat). He also developed and introduced
many measuring tools taking after his name, such as the Abbe
refractometer, the Abbe apertometer and the Abbe sinecondition test chart, to check material quality and thatprocessing and assembly were being carried out according to
the design values. In 1872, Zeiss abandoned its conventional
manufacturing method based on the experience and intuitionof craftspeople and switched completely to using Abbe’s
designs, securing its position as the world’s leading
manufacturer. That year, using a vast number of calculations
and experiments, Abbe derived a theory of image formationthat the numerical aperture had to be larger for the objective
lens to capture high-order diffraction rays from the object,which was necessary for accurately reproducing
microstructures as images. He showed that microscope
resolving power δ could be represented as δ = λ/2NA (where λis the wavelength). Abbe also developed the Abbe condenser(Figure 2.32) the same year, having found during thisresearch that the illumination system also needed to performbetter. In 1877, Abbe developed homogenous immersion(HI), using cedar oil, which has a similar refractive index tothe cover glass and lens apex. This design made it possible toFig. 7.1 Lister Objective Lens
(created with reference to cited reference 1)

Fig. 7.2 Amici Objective Lens
(created with reference to cited reference 1)

60

eliminate aberration, even with a high NA, since the second
spherical surface of the objective lens worked as a refractive
surface, not the first surface. Recognizing the importance of
optical materials, Abbe met with Schott (Figure 3.7) and in1882 the two jointly established an optical glass factory in
Jena to research and develop new types of glass. In 1886,
Abbe used a new type of barium crown glass and natural

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. Marchfluorite (CaF2) to produce an apochromatic objective lens thatlenses. Later, Zeiss and Leitz added Plan objective lens series

was achromatic over the entire range of visible light. Unlike
optical glass with regular dispersion properties, fluorite hasto their lineups. The development of the highest quality Plan

anomalous dispersion properties (see 2.1.1) and can achieveeffective achromaticity for a third wavelength when used as apredominance of German microscopes.

Apochromat objective lenses demonstrated the unwavering

convex lens. However, natural fluorite is a difficult material
to work with, as it is difficult to get superior transparency andhomogeneity, it scratches easily (4 on the Mohs hardness
scale) and, being a crystal, does not lend itself well to highprecision polishing. Figure 7.3 shows the structure of anapochromatic lens 60× (dry system = not oil immersion, ×represents magnification). The shaded lenses in the figure are
made of fluorite.

Fig. 7.4 Zeiss Plan Achromat 40× /0.65(created with reference to cited reference 3)

7.1.2

Advances in Objective Lens RelatedStandards and Technology (see 2.4)

(1) Mechanical Tube Length
The mechanical tube length is the distance from theFig. 7.3 Zeiss Apochromat 60× /0.95(created with reference to cited reference 2)

If the Lister and Amici achromatic lenses were the firststep in microscope objective lens development and theapochromatic lens mentioned above was the second step, then
the third step would be the plan lens. Microscope objective
lenses do not have as wide a view angle as photographic
lenses. High magnification lenses in particular have such ashort focal length that the curvature of field cannot readily becorrected. Focusing on the center of the field of view makes
the peripheral edges blurry. With the increase inphotomicrography in the 20th century, there has been agrowing need to have the entire field of view in focus.
Although a method was used to correct field curvature using

objective lens revolving nosepiece mount to the eyepiecetube mount. The distance of 160mm, recommended by theRoyal Microscopical Society (RMS) in 1882, was adopted by
Zeiss and many other manufacturers, although not all. For
example, Leitz used a distance of 170mm. The related
German industrial standard Deutsches Institut für Normung(DIN) 58887 was published in 1975, stipulating 160mm andinfinite distance. At that point, Leitz changed from 170mm to160mm. Infinity-corrected mechanical tube length opticalsystems emerged in the 1920s and 30s and had been sold by
Zeiss and Leitz for metallurgical microscopes. However, thissystem saw little growth in popularity over the next 60 years.
It was not until Zeiss announced the ICS optical system in1986 that major manufacturers, including Japanesecompanies, began adopting infinity-corrected optical systems.

a negative projection lens for photography (Zeiss called thisthe Homal), there was strong demand to be able to correct
field curvature and peripheral aberration using the objective
lens alone. Other methods to correct curvature of field
include using a convex lens with a high refractive index and aconcave lens with a low refractive index or using strong
negative meniscus lenses (lenses with surfaces on both sides
curving in the same direction). Since microscope objective
lenses are often made from low refractive index, lowdispersion glass to correct chromatic aberration, the first
method was difficult to design and deploy. The second
method required a high level of competence in complex lensdesign to produce a well-balanced design to also compensate
for peripheral aberrations. The first Plan objective lens was
designed by P. H. Bögehold (1876-1965) of Zeiss and(2) Parfocalizing Distance
The parfocalizing distance is the distance between thespecimen and the objective lens revolving nosepiece mount.
This is designed with a constant value to ensure that the focus
is maintained when the revolving nosepiece is turned tochange the objective lens. Many companies previously used avalue of around 37mm, although most German manufacturers
used 45mm. After DIN 58887 was published, stipulating
45mm, Japanese companies also transitioned to new opticalsystems with a 45mm parfocalizing distance. However,Nikon adopted a 60mm parfocalizing distance for its CFI60
series in 1996 and has continued to use this distance eversince.

patented in 1938 (Figure 7.4) 3). The first lens on the object
side and the last lens on the image side are strong meniscus
Systematic Survey on Optical Microscope Technology in Japan

61

(3) Screw Thread Shape (see Table 2.1)
The shape of the screw thread for mounting the objective
lens onto the revolving nosepiece affects the mechanicalcompatibility of objective lenses from different companies.
The dimensions specified by the RMS have long been used as
the standard dimensions and are still used by many
manufacturers today. This specification is known as the
Whitworth screw, with a thread angle of 55°, outer diameterof 20.32mm (0.8″) and pitch of 0.706mm (1/36″). However,with objective lenses growing in diameter in recent years,
M25 and M27 threads are now also being used. Reflected
light dark field objective lenses have a larger thread diameterto allow illumination light around them. These use W26, M27
or M32 diameter values. All of these, including factors suchas dimensional tolerance, are stipulated in ISO 8038 (JIS B
7141). Table 7.1 shows the focal length, parfocalizing
distance, screw thread shape and year of adoption for theinfinity-corrected mechanical tube length optical systems ofmajor microscope manufacturers.

company named a successful prototype lens the “Zuikō”, aJapanese abbreviation of the name of the laboratory 6).Prior tothat, Nippon Kogaku had employed eight engineers from
Germany in 1921, after Germany was defeated in the FirstWorld War. These engineers worked on research andintroducing technology for optical designs, design drawings,
glass processing and machine processing 7) 8). Among theengineers were optical design expert M. Lange andmicroscope designer H. Acht. As well as working on various
camera lenses (the prototypes for the later “Nikkor” lens),
these two, especially Acht, worked on designing anddeveloping the objective lenses for Nippon Kogaku’s firstmicroscope, the JOICO (Figure 4.9). Acht’s design data andGerman design methods served as a basic design resource forlater photographic lenses. Later, as Japan grew increasingly
militant, optical companies began devoting their resources todesigning and manufacturing optical military equipment,such as binoculars, sights, range finders and periscopes. Great
progress was made in Japanese optical technology.
After the war, optical instruments transitioned into apeacetime industry. With growing demand for binoculars andcamera lenses, optical companies devoted their efforts todeveloping new products. Designing new lenses was done by
coming up with different lens types and glass combinations.
This meant tracing several hundred light rays using
trigonometric functions, which required vast amounts ofmathematical calculations. These were all completed
manually, logarithm tables on hand (Figure 7.5). One highend lens could take three years to design. Designers alsoacquired knowledge and techniques from lens design
literature, such as “Applied Optics and Optical Design”(Conrady, 1929, Part 1) 9), “Grundlagen der praktischen
Optik” (Berek, 1930) 10) and “Renzu no Sekkei to Sokutei[Lens Design and Measurement]” (Ashida Seima, 1940) 11).
In 1951, Suzuki Tatsurō (1919-1993) et al. published an
academic paper on a lens design method 12) 13).

7.2 Advances in Lens Design
After Abbe started developing microscope lenses at Zeissusing ray tracing, other companies in the West began
adopting this method and producing microscopes withsuperior optical performance. In Japan, the objective lenses
used in the Tanaka microscopes and M & Katera were
manufactured by engineers taking apart, analyzing,measuring and reproducing these Western lenses by trial anderror to ensure their performance by any means possible. It
was a natural progression for these business owners toprioritize optical design research. M & Katera Optical Works
founded the M & Katera Optical Research Laboratory in1931 and began working on lens design using manual
calculation 4) 5). In 1935, Takachiho founded Mizuho Optical
Research Laboratory and began working on mathematicaldesigns for photographic lenses. The following year, theTable 7.1 Optical System Related Dimensions of Major Microscope Manufacturers
Manufacturer(optical system)

Tube lens focal
length (mm)*Parfocalizing
distance(mm)

Screw thread shape( ) means reflected
light dark field

E. Leitz(DELTA)(HC)(CF)(CF & IC)
(CFI60)
(LB)
(IC)
(UIS)

250
200
200
(MTL = 160, 210)
200
200
(MTL = 160)
180
180

45
45
45
45
45
60
45
45
45

RMS
M25 (M32)
M25 (M32)
RMS
RMS (M27)
M25 (M32)
RMS
RMS (W26)
RMS (W26)

For Axiomat
(ICS)

250
164.5

45
45

M27
RMS, M27 (M27)

Leica
Nikon
Olympus
Zeiss

Year transitioned to infinity
corrected optical system
Metallurgical /Biologicalindustrial—
1931, 1972
1992
1997
1976
—
1994
1996
1999
1978
―
—
1981
1993
1994
—
1924
1973
1986

(* MTL in parentheses stands for mechanical tube length in finite corrected optical system)

62

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. MarchFig. 7.5 Female Employees Working on Lens Design
Calculations 7)

This method used the differential calculation coefficients ofeach lens component to effectively estimate the rates ofvariability for different lens aberrations. The introduction of
Monroe electronic calculators (Figure 7.6) from 1953
increased the calculation efficiency several times over that of
calculation by hand. Fuji Photo Film (now FUJIFILM)
devised a way to automate lens design and spent seven years
developing the FUJIC, Japan’s first working electronic digitalcomputer, completed in March 1956 (Figure 7.7). Thismachine increased the calculation efficiency around 2000
times over that of calculation by hand. Relay automatic
calculators were introduced to the production system in 1957.
Olympus bought a FACOM 138, the first automatic
calculator commercialized in Japan (Fuji Tsushinki, now
Fujitsu), while Nippon Kogaku bought a similar Germanmachine the same year. Nippon Kogaku introduced anelectronic computer in 1962 and Olympus did the same in
1963, dramatically increasing calculation speeds. Researchon how to use electronic computers to correct lens aberration
had begun around 1955.

Fig. 7.6 Monroe Electronic Calculator 7)

Fig. 7.7 The FUJIC, Japan’s First Automatic Calculator(held by the National Museum of Nature and Science, photographed by
the author)

Major optical manufacturers started building their own lensdesign computer programs, incorporating aspherical surfaces,
zoom lenses and other design considerations to achieve toplevel, world-class optical design technology. Later advancesin supercomputers, microcomputers and personal computers
and the accompanying increase in processing power anddecrease in cost gave designers greater control to produce
high-end lens designs. Commercial lens design software also
grew in popularity, making it now possible even for
individuals to design high-end lenses.

7.3 Advances in Optical Glass 14)
The first research on glass used in lenses, or optical glass
production methods, was carried out by P. L. Guinand (17481824) of Switzerland. After the discovery of achromaticlenses and as lead-oxide-rich flint glass (used widely by
craftspeople) began to be used in lenses, there were issues
with cords or striae and other refractive index irregularities
and issues with visible light transmittance. Around 1790,
Guinand came up with a method of melting the materials in a
crucible at high temperature and stirring them mechanically.
This method is still used today. Fraunhofer took this method
and further improved it to successfully produce large
amounts homogenous optical glass in 1812, which he used tocomplete a 175mm diameter achromatic objective lens for atelescope. He also made detailed refractive index readings ofthe dark lines he discovered in the solar spectrum (Fraunhoferlines) and based his lens design and production on this data.
French company Parra-Mantois and British company Chance
Brothers continued with Guinand’s production method andthe two countries became major suppliers of optical glass in
the late 19th century. There were further advances in lensdesign theory and high hopes for new types of optical glasswith refractive index and dispersion properties not found in
the existing optical glass to correct various aberrations in abalanced manner. German optical glass researcher Schott met
with Abbe of Zeiss, who had established the design theory for
microscope objective lenses and observed the properties of
optical glass, and in 1884 the two jointly developed new
types of glass, such as barium crown glass, and alsoestablished an optical glass factory in Jena (see 3.4). This
glass had a higher refractive index than existing glass, which
made it very useful for designing apochromatic objective
lenses and high-performance photographic lenses. A
company catalog published in 1886 lists 44 types of opticalglass and their characteristics and prices, including 19 new
types of glass. By 1888, 24 more types had been added. The
following year, dense crown glass was successfully
developed. The 1913 catalog lists 97 types of glass, including
17 new types, while the 1923 catalog lists 114 types,
including 22 new types of glass. Figure 7.8 shows an opticalglass map from the 1923 catalog, believed to be the earliest

Systematic Survey on Optical Microscope Technology in Japan63

by Schott. The existing types of glass form an arc from theupper right of the figure to the lower left, with many new
types of high refractive index glass widely distributed. Due to
Schott’s development of new glass and superior productquality control, Schott glass gained a high reputation as “Jenaglass”, surpassing optical glass from Britain and France.
Later, G. W. Morey of the United States developed highrefractive index lanthanum glasses, containing rare elements
such as lanthanum (La), thorium (Th) and tantalum (Ta).
These glasses dramatically improved the potential of opticaldesign.

When optical glass production resumed in Japan after thewar, there was a growing demand for optical glass, mainly
for camera lenses. There was also strong demand for highrefractive index glass. Optical glass manufacturers begansharing technology and collaborating on research with
universities and government research stations. In 1948,
collaborative research by five members of the Japan Optical
Glass Manufacturers’ Association resulted in thedevelopment of a new type of glass. To achieve a highrefractive index required glass containing elements such as
lanthanum (La), tantalum (Ta), titanium (Ti) or zirconium(Zr). As this glass was difficult to melt in conventional clay
crucibles, platinum crucibles began to be used in glass
production. Prominent manufacturer Ohara successfully
developed LaSF glass (now called S-LAH) in 1958, with arefractive index of 1.8. The number of glass types increased
to 138 by 1962, 207 by 1967 (Figure 7.9) and 229 by 1986.
Meanwhile, Schott successfully developed a low refractive
index, low dispersion glass (ED glass) called FK01 (now SFPL51) in 1975. followed by FK03 (now S-FPL53) in 1989,
which had almost identical optical properties to fluorite. This
made it possible to transition away from fluorite, which was
expensive and difficult to work with, and contributed greatly
to the design and development of apochromats, semiapochromats and other high-quality microscope objective
lenses.

Fig. 7.8 Schott 1923 Optical Glass Map 15)

In Japan, many ordinary glass industries came into being
in the early 20th century, but manufacturers of colorless,homogenous optical glass were nonexistent. This glass had tobe imported. The first optical glass was successfully
produced by the naval arsenal in Tokyo (Tsukiji) in 1918.
After that, Nippon Kogaku took the lead in developing andproducing glass, achieving success in high volume melting in
1927 and producing 15 types of glass by around 1935. That
year, principal researcher Ohara Jinpachi (1888-1968)
founded the Ohara Optical Glass Manufacturing Company(now Ohara Inc., referred to below as Ohara) and became
Japan’s first specialized optical glass manufacturer. The
company continues to supply optical glass to many optical
instrument manufacturers today. Fuji Photo Film (nowFig. 7.9 Glass Chart from 1967 (nd – vd) Ohara Optical
Glass 16)

FUJIFILM) started producing optical glass in 1938, while the
Chiyoda Optical Seiko (now Konica Minolta) did the same in1944. Toyo Optical Glass Manufacturing (now HOYA) was
founded in 1941 to produce optical glass, as was the Sumita
Optical Glass Manufacturing Company (now Sumita Optical
Glass Inc.) in 1953.

The Ohara Optical Glass Manufacturing Company
changed its name to Ohara Inc. in 1985. In 1990, thecompany named its own glass instead of using names
designated by Schott. It also led the world in developing leadfree and arsenic-free glass as an environmental measure,announcing this initiative in 1991. After that, out ofconsideration for eco-friendly resource conservation, thetypes of glass dropped from around 250 to 112. By 1997, all64

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. Marchrecommended optical glass was eco-friendly. Short flint(KzF, KzFS), the anomalous dispersion glass used in
microscope objective lenses, also ceased production.
However, research on an eco-friendly alternative resulted in
the successful development of S-NBH and S-NBM glass in
1998. Initiatives to develop an optical glass with low
autofluorescence to use in fluorescence microscopes
culminated in the announcement of a new type of S-NBH

1/12 objective lens in 1918 (focal length in inches, around90×). Along with this, improvements were also being madeto the accuracy of the fine movement mechanism for focusing
and the cross-motion stage mechanism for moving thespecimen in the XY direction. In 1924, a high-end
microscope was developed with a total magnification of
1000×. Takachiho had produced a 100× objective lens in1920 (Figure 7.10) and launched the GK high-end oilimmersion microscope (“Showa”) in 1927.

glass in 2007. Further progress was made on high refractive
index glass and now there are several types of glass on themarket with a refractive index of over 2.0. Figure 2.4 shows
the latest optical glass map (Ohara).
Ohara, HOYA, Sumita Optical Glass, Hikari Glass (Nikon
Group since 2004) and other outstanding optical glass
manufacturers have been proactive in understanding global
trends and the needs of optical instrument manufacturers.
These Japanese companies have worked on developing new
types of optical glass and making improvements to productquality and cost. This has been a key contributing factor inJapan continuing to remain at the top of the global opticalindustry.

7.4 Japanese Development of Objective
Lenses
7.4.1
To 1945 5) 6)
Industrial production of microscopes in Japan, as
mentioned in 4.2, began with copying products imported
from Leitz and other overseas companies. However, this wasa constant struggle, as there were significant differences in
performance and there was no access to design data including
optical materials, especially for producing objective lenses.
According to Suzuki Taiichi, an apprentice to Katō Kakitsu
in charge of lens machining and assembly at M & Katera,
early objective lens manufacturing was as follows, “Wewould cut Leitz objective lenses through the center andmeasure their thickness, curvature and distances, etc. andthen grind out several types of glass we had in stock andreplace them for the Leitz lenses one by one to decide whichglass was best. We repeated this endlessly and managed to
produce what looked like objective lenses using only the
glass we had. But ordinary grinding methods were no goodfor the top high magnification objective lens, which was
hemispherical or thicker with a narrow radius of curvature, so
we would stick the lens on the head of a nail on the end of apole and manage to grind it that way. Our glass was made up
of different materials from Leitz lenses, so some of our lenses
would not focus, even when touching the specimen coverglass. Lens manufacturing in those early days was done in a
special small room in the factory with a contact window. The
technology was almost like a secret art.” Improvements weremade through these vast amounts of trial and error. Objective
lens machining and assembly technology steadily improved.
M & Katera Optical Works released its first oil-immersed

Fig. 7.10 Achromat 100×oil-Immersion Lens
Cross Section 17)

However, the highest quality objective lens in the world
was the Apochromat, completed by Abbe in 1879. Due to the
distinctive characteristics of the glass, it was thought to be
impossible to manufacture in Japan. In 1928, TakachihoWorks started researching the Apochromat, funded by anindustrial research grant from the Ministry of Commerce andIndustry. One of the materials in the convex lens wascolorless and transparent natural fluorite. The company did
not know where to obtain this and searched everywhere for asource. It was found to be naturally present at Obira mine(Ōita prefecture). As fluorite is a crystal with low hardness,processing it for high-precision lenses required a lot of skill
and expertise. Alum was also used as another material for aconcave lens. There were anecdotes of this substancedeliquescing and disappearing during research and analysis.
The grinding method and frame structure for the alum lensalso needed new technological development.

Fig. 7.11 Apochromat 90×oil-Immersion
Objective Lens 18) 19)a) Front sideb) Reverse sidec) Cross section 17)

Systematic Survey on Optical Microscope Technology in Japan

65

Researchers persevered through these setbacks to produce a
90× Apochromat oil-immersion objective lens prototype in1931 (NA 1.30, Figure 7.11), followed by 10× (NA 0.30) and20× (NA 0.65) Apochromats and a 40× Apochromat dry
objective lens (NA 0.95) with a correction collar in 1934
(Figure 7.12). These were launched in combination with the“Fuji OCE” high-end microscope 6) 17).Completing these
Apochromats was a ground-breaking result, indicating therising level of optical technology in Japan at the time.

completed its Plan objective lens series for industrial
microscopes in 1966 (mechanical tube length 200mm,
parfocalizing distance 42.5mm), while Nippon Kogaku did
the same around 1970 (mechanical tube length 210mm,
parfocalizing distance 33.6mm). Compared to Achromat
objective lenses, these have more lenses, including meniscus
lenses, and use more fluorite and ED glass with higher
magnification.
OlympusAch objective lenses
mechanical tube
length= 160mmparfocalizing
distance= 36.65mm

Fig. 7.13 Structure of Achromat Objective Lenses
Fig. 7.12 Apochromat Objective Lensesa) 10×b) 20× c) 40× with correction
collar(Olympus) 21)

19)d) Ditto,
Reverse side

Nippon Kogaku
Ach objective lenses

7.4.2

Development from 1945 to 1975

After the war, the Japanese microscope industry resumed
production of its prewar models, but as demand grew, there

mechanical tube
length= 160mmparfocalizing
distance= 33.6mm

was also demand for higher performance. While
manufacturers of course worked on mechanical precision, aFig. 7.14 Structure of Achromat Objective Lenses

major challenge was improving the optical components,(Nippon Kogaku) 22)

especially the objective lens. In 1950, the first issue of the
Journal of the Mechanical Testing Laboratory was published,“Kokusan Kenbikyō no Genjō [Current State of Domestically
Produced Microscopes]”, including promising results of areview of objective lenses indicating that Japanese lenses
were not inferior to Western lenses. However, the objective

OlympusPlan objective lenses
mechanical tube
length= 160mmparfocalizing
distance= 36.65mm

lenses reviewed were only achromats, not apochromats or
semi-achromats (fluorite). Flat-surfaced plan achromats had
also not yet been developed by any company. Thus, it wasconceded that overall microscope optical performance inJapan was still largely trailing behind the West.
Olympus and Nippon Kogaku both added plan objective
lenses to their lineup between 1963 and 1967. In contrast, apaper published in 1964 described a total of 66 types of
biological and industrial plan objectives produced by Leitz,
ranging from 1× to 160×, showing a stark contrast intechnological development capabilities 20). Figures 7.13 and7.14 show the structures of Olympus and Nippon Kogaku
Achromat objectives (Ach) at the time, while Figures 7.15
and 7.16 show the two companies’ Plan Achromat objectives(Plan). The horizontal lines in the upper section of eachfigure indicate the objective lens mounting position(revolving nosepiece mounting position), the lenses withdiagonal lines and cross hatching indicate ED glass andfluorite, respectively (the same applies below). Olympus

66

Fig. 7.15 Structure of Plan Achromat Objective Lenses(Olympus) 21)
Nippon Kogaku
Plan objective lenses
mechanical tube
length= 160mmparfocalizing
distance= 33.6mm

Fig. 7.16 Structure of Plan Achromat Objective Lenses(Nippon Kogaku) 22)

The highest quality plan apochromat (PlanApo) objective
lens had been manufactured in series in Germany since the1950s. In Japan, Nippon Kogaku launched the first PlanApo
100×oil-immersion objective lens (Figure 7.17) and plan

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. Marchfluorite PlanFl 40× in 1964. Olympus had completed anapochromat objective lens series before the war, but after the
war only continued with semi-apochromat objective lenses
using fluorite, the Fl 100× (NA 1.30, oil-immersion) and Fl
40× (NA 0.77), released in 1953-1955. The company
completed a plan apochromat series comprising 4×, 10× and20× lenses in 1972, followed by a 40× with a correction
collar and an oil-immersion 100× in 1974 (Figs. 7.18 and7.19). The most difficult of these was the 100×, made up of atiny hemispheric front lens of crown glass with a refractive
index almost identical to that of the immersion oil and ameniscus lens made of flint glass with a very high refractive
index (Figure 7.20). The rearmost concave lens was made upof three layers, consisting of alum with anomalous dispersion
properties (n=1.456) sandwiched between regular glass
lenses (the dotted area shown in the figure). Engineers had tostudy in Germany to learn the grinding technology to achievethis. Japanese objective lenses seemed to catch up theGerman lenses technically, but were still no match in terms ofactual overall performance.

Flint glass (n=1.89)
Crown glass (n=1.52)
Immersion oil (n=1.52)
Cover glass (n=1.53)
Specimen

Fig. 7.20 Structure of Plan Apochromat 100×oil Front Lens

7.4.3

Development from 1976 to 1992

Japanese microscope manufacturers added new models totheir lineups, from ordinary educational and student
microscopes to high-end microscopes for cutting-edge
research. These were well received and their market share
grew, although they still were not as highly regarded as theworld-leading German microscopes, especially in fields suchas biomedical research. To overcome this situation, Japanesemanufacturers had to engage in research and development torebuild their entire microscope systems, and above all, toachieve top-ranking optical performance.
Nippon Kogaku led out by changing the parfocalizing
distance of its objective lenses from 33.6mm to the 45mm
specified by the German industrial standard (DIN) (nochange to the 160mm mechanical tube length). The company
also made plans to redesign the optical system and embarked
on a project with members from business, design, technology
and manufacturing. The change in parfocalizing distance was
useful in adding a greater degree of freedom in opticaldesign, but it disadvantaged users in terms of compatibility
with other microscope systems. The decision was made basedon this issue. It was common practice in optical design to use

Fig. 7.17 Nippon Kogaku Plan Apochromat 100×oila) structural view

22)b) external view

(Mechanical tube length: 160mm; parfocalizing distance: 33.6mm; NA:
1.30; WD: 0.12)

the compensation method established by Abbe in the late 19th
century to correct lateral chromatic aberration between theobjective lens and the eyepiece. By contrast, Nippon Kogaku
designed a new chromatic aberration free system (CFsystem), in which chromatic aberration in the objective lensOlympusand eyepiece are corrected separately. After testing this new
design against the conventional system, the decision was

PlanApo objective
lensesmade to transition to the new system and development began

mechanical tube
length= 160mmparfocalizing
distance= 36.65mm

23) 24). The CF system has the following five distinguishing

characteristics.
NA

Fig. 7.18 Structure of Plan Apochromat Objective Lenses(Olympus) 21)

1) Lateral chromatic aberration is corrected properly fromthe center of the field all the way to the peripheral edge.
2) There are no changes in color at field stops of eyepiece,
allowing 100% effective field viewing (in theconventional system, there are red tinges inside of thestops).
3) When a graticule is inserted into the eyepiece, there areno color changes around the graduated scale or numbers.
4) Longitudinal chromatic aberration is improved for theobjective lens and eyepiece.

Fig. 7.19 Plan Apochromats(from left) 4×, 10×, 20×, 100×oil 21)

Systematic Survey on Optical Microscope Technology in Japan67

5) Both the objective lens and eyepiece are their own
complete optical systems and can be applied to any field.
The Abbe compensation method was adopted because it
was difficult to correct lateral chromatic aberration,
particularly for high magnification objective lenses. This was
resolved by dividing the objective lenses into front and reargroups and over-correcting the front group, then inversely
correcting the rear group. Figure 7.21 shows the structures of
CF system Achromat (Ach) objective lenses, Plan Achromat
objective lenses (Plan) and Plan Apochromat objective lenses(PlanApo). The distinguishing characteristics are clearlyshown when compared to the conventional structure of theAch 40× and 100×oil (e.g. Figure 7.14). For high-quality
Plan and PlanApo objective lenses, aberrations such as strong
chromatic aberration and curvature of field could becorrected even at high numerical aperture by using fluorite or
the newly developed ED glass. For epifluorescence, the CF
UV-F series was also added to the lineup, lenses with low
autofluorescence and high transmittance in the nearultraviolet range. Figure 7.22 shows the external view ofdifferent biological CF series objective lenses. The CF MPlan(structure shown in Figure 7.23) and CF MPlanApo
metallurgical objective lens series were also developed(mechanical tube length 210mm, parfocalizing distance45mm), as well as the CF BD Plan and CF BD PlanApo
series for reflected light bright/dark field microscopy. The CF
system was launched in 1976 in three microscopes in the
newly developed high-end Microphot V series: the Biophot
biological microscope (Figure 4.31), the Fluophot
fluorescence microscope (Figure 5.38) and the Metaphot
metallurgical/industrial microscope (Figure 6.57).

Fig. 7.22 Nippon Kogaku Biological CF Objective Lenses 22)a) Ach series: front row 4× 10×; back row 20×, 40×,
100×oilb) Plan series: front row 4×, 10×, 20×; back row 40×,
40×NCG (no cover glass), 100×oil, 100×oil with irisc) PlanApo series: front row 4×, 10×, 20×; back row 40×,
60×, 100×oil, 100×oil NCG (no cover glass)d) UV-F series:10×, 20×, 40×gly, 100×gly (gly refers toglycerol immersion)

NipponKogakuCF MPlan
objective lensmechanicaltube length= 210mmparfocalizing
distance= 45mmFig. 7.23 Structure of Nippon Kogaku CF MPlan Objectives

Nippon Kogaku(extract from series) 22)

CF Achmechanical tube
length= 160mmparfocalizing
distance= 45mm

Nippon Kogaku
CF Planmechanical tube
length= 160mmparfocalizing
distance= 45mm

Nippon Kogaku
CF PlanApo
mechanical tube
length= 160mmparfocalizing
distance= 45mmFig. 7.21 Structure of Nippon Kogaku CF Objective Lenses(extract from Ach, Plan, PlanApo Series) 22)

68

Olympus started planning development of a new opticalsystem in 1974, changing the parfocalizing distance from theexisting 36.65mm (42.5mm for metallurgical) to the 45mm
specified by the DIN. The distinguishing characteristics ofthis long barrel (LB) biological microscope objective lenssystem are given below 25).
1) The main Plan objective lens series are the high-grade
SPlan and the regular DPlan series.
2) The high-end SPlanApo series increases the NA andcompletely corrects chromatic aberration.
3) The standard field number increased from 18 to 20,
intended to enlarge objective lens working distance andimprove operability.
4) SPlanFl 1× and 2× very low magnification objective
lenses added to the lineup with the same parfocalizing
distance as other magnifications.
5) Improved image contrast range using new ED glass andnew multicoating technology.
6) Ach and regular Plan objective lenses designed to reduce
costs while maintaining or improving existing
performance.
7) Basic optical design concept is that lateral chromaticaberration remains the same as the compensation methodwith 160mm mechanical tube length.

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. March

However, not long after this design was established,
Nippon Kogaku announced the CF optical system and a new
microscope series. Olympus hurriedly pushed forward with
the SPlan series and released it on the market in 1978 (themicroscopes were the AH-LB and the BH-LB). In developing
the LB, the company had formed an internal advisorycommittee for matters relating to design, processing andevaluation. The committee was involved in the developmentof various technical elements, including development andtheoretical optimization of a new phase film for phase
contrast microscopy and development of non-fluorescent oil(silicone oil) for epifluorescence microscopy. Figure 7.24
shows the structure of the DAch, SPlan and SPlanApo in the
LB objective lens series. Figure 7.25 shows photographs ofthese lenses.
Olympus
LB seriesDAchmechanicaltube length= 160mmparfocalizing
distance= 45mmAfter bringing the LB optical system to a certain point ofcompletion, Olympus moved on to developing
metallurgical/industrial objective lenses. The design concept
was not simply lengthening the parfocalizing distance from
42.5mm to 45mm, but changing the mechanical tube lengthfrom the conventional 200mm to an infinity corrected opticalsystem (see 2.4). The objective lens series was named theinfinity corrected (IC) optics 26). Since the tube and eyepiece
were the same as for the LB optical system, the compensation
method was used for correcting lateral chromatic aberration.
The focal length of the tube lens was set at 180mm after
various testing. Like the biological LB system, the plan
objective lenses were divided into the high-grade MSPlan
series (Figure 7.26a) and the regular MDPlan series. These
were joined in the lineup by the bright and dark field
NeoSPlan series (Figure 7.26b) and NeoDPlan series. These
were all launched in 1981, together with the MSPlan-NIC
and NeoSPlan-NIC series with reduced optical strain forreflected polarized light / differential interference contrast
microscopy and the ultra-long working distanceULWDMSPlan (Figure 7.26c) and ULWDNeoSPlan(Figure7.26d). Including later additions, the number ofobjective lenses has grown to over 50 types.

Olympus
LB seriesSPlanmechanicaltube length= 160mmparfocalizing
distance= 45mmOlympus
LB series
SPlanApo

Fig. 7.26 Olympus IC Objective Lenses 21)

mechanicaltube length= 160mmparfocalizing
distance= 45mma) MSPlan 1.5×, 2.5×, 5×, 10×, 20×, 50×, 100×dry, 100×oil,
MSPlanApo 50×b) NeoSPlan 5×, 10×, 20×, 50×, 100×c) ULWDMSPlan 20×, 50×, 80×d) ULWDNeoSPlan 20×, 50×, 80×Fig. 7.24 Structure of Olympus LB Objective Lenses(extract from DAch, SPlan, SPlanApo series) 21)

Fig. 7.25 Olympus LB Objective Lenses (Biological) 21)

Precision measuring instrument manufacturer Mitutoyo
Manufacturing (name changed to Mitutoyo Corporation in
1987, referred to as Mitutoyo below) joined the microscopeindustry in 1984 with the launch of the FS optical microscope
series, mainly aimed at the industrial market. The mostprominent feature of this series was the infinity corrected
objective lens series (tube lens focal length 200m), with aparfocalizing distance 95mm, more than double the standard
parfocalizing distance (not stipulated in ISO 9345-2 or JIS B
7132-2) 27) 28). The standard MPlanApo and the bright/darkfield BD PlanApo series were designed with an ultra-longworking distance to make good use of the particularly long
parfocalizing distance. The series also featured Apochromat
lenses using many ED glasses.

a) DAch 4×10×, 20×, 60×, 40×, 100×oilb) SPlanFl 1×, 2×, SPlan 4×, 10×, 20×, 40×, 100×oil, 100× dryc) SPlanApo 4×, 10×, 20×, 40×, 60×oil, 100×oil (with iris)
Systematic Survey on Optical Microscope Technology in Japan

69

Table 7.2 Mitutoyo MPlanApo Objective Lens Specifications
MPlanApo

1×
0.025
11

2×
0.055
34

5×
0.14
34

7.5×
0.21
35

10×
0.28
33.5

MPlanApo-SL
MPlanApo-HR

0.21
25.5

0.42
15

20×
0.42
20
0.28
30.5

50×
0.55
13
0.42
20.5
0.75
5.2

80×

0.5
15

100×
0.7
6
0.55
13
0.9
1.3

200×

0.62
13

(top line: NA, bottom line: WD)

Table 7.2 shows the specifications of the MPlanApo, thelong-working-distance MPlanApo-SL and the high-NA
MPlanApo-HR series. Figure 7.27 shows photographs of theMPlanApo series. Maintaining its presence in the industrial
market, Mitutoyo later expanded its lineup with the MPlanNIR and LCD inspection LCDPlan-NIR series withchromatic aberration correction for visible and near-infrared
light and increased near-infrared transmittance, the MPlanNUV and LCD inspection LCDPlan-NUV series withchromatic aberration correction for visible and nearultraviolet light and increased near-ultraviolet transmittance,
the MPlan-UV series with fluorite and synthetic quartz lenses
to ensure UV transmittance and performance, and the
GPlanApo series, designed for viewing through a thick
3.5mm cover glass.

Fig. 7.27 Mitutoyo MPlanApo (back row) and MPlanApoHR (front row) Series 29)

Nippon Kogaku launched the Microphot FX high-end
universal photography microscope in 1985 together with new
NCF series objective lenses, which had better contrast andresolving power than the existing CF series. The NCF Plan
and NCF PlanApo series (Figure 7.28) had higher numericalapertures than the CF Plan and CF PlanApo, rivalling the
SPlan and SPlanApo by Olympus.
7.4.4
Developments Since 1993
Changes in parfocalizing distance and the transition of
metallurgical/industrial objective lenses to infinite
mechanical tube length continued in Japan. In 1986, as thiscame to near completion, Zeiss announced a succession of
new microscopes featuring a completely new infinity colorcorrected system (ICS) 30), including the Axiophot, Axioplan,
Axiotron and Axiovert (see 4.7). The ICS system wasdesigned for infinity corrected mechanical tube length as wellas lateral chromatic aberration correction in both biologicaland metallurgical/industrial microscopes.
All the objective lenses and eyepieces were completely new
designs, evidence of the company’s credibility as a leader inhigh-end microscopes. The tube lens was combined with theobjective lens and corrected all aberrations. The idea of an
infinity corrected optical system for biological microscopes
was not new, but the full-scale adoption of it by Zeiss gained
the approval of biomedical researchers around the world.
Leica announced the Delta optics system 31) using a similar
idea in 1992 and developed it into the harmonic compoundsystem (HCS) in 1998.

NipponKogakuNCF Plan
objective lensmechanicaltube length＝160mmparfocalizing
distance＝45mm

NipponKogakuNCF PlanApo
objective lensmechanicaltube length＝160mmparfocalizing
distance＝45mm

Fig. 7.28 Structure of Nippon Kogaku NCF Objective Lens
(extract from NCF Plan, NCF PlanApo Series) 22)

70

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. MarchIn Japan, Olympus started investigating how to adopt this
optical system. In 1988, after studying the technological andbusiness aspects of it, the company started a development
project, having decided to use the new concept to completely
redesign its objective lenses and eyepieces for biological andmetallurgical/industrial microscopes. The optical system wasnamed the universal infinity system (UIS), designed forsystem scalability in order to incorporate various needs andperform at a world-class level 32) 33). The distinguishing
characteristics of the system are given below, with respect to
how it differs from the prior ICS series.
1) It offers world-class resolving power and contrast for all
types of microscopy.
2) It has high system scalability through infinity correction,with biological and metallurgical/industrial microscopes
using the same design concept.
3) It is a highly scalable, fully flexible system thatcompletely corrects all aberration in the objective lens,
tube lens and eyepiece respectively.
4) It has a lineup of universal objective lenses in one series
that can be used for various different types of
microscopy.

5) It is designed for significantly improved operability, withthe standard field number increased to 22 (previously 20)
and the objective lens working distance (WD) also
increased.
Following a variety of design tests and prototype
evaluations, the tube lens focal length was set at 180mm, thesame as the IC optical system. There were two series ofuniversal objective lens, the Plan Apochromat and the Plan
Fluorite. This was difficult to design, as these needed tomaintain the original high level of bright field performance aswell as achieve improved near-ultraviolet transmittance andpolarized light characteristics. The degree of design freedom
was limited by the selection of glass, which had to have highnear-ultraviolet transmittance and low autofluorescence,
especially for fluorescence microscopy. It was around thistime that special optical glass with near-identical properties
to fluorite emerged, such as FK03 (made by Ohara, now
called S-FPL53) and GFK70 (made by Sumita Optical Glass,also called Gadron) (see 7.3). These types of glass were usedin lens design as a substitute for the difficult-to-process
fluorite, which led to improved productivity. The
development of broadband anti-reflection coating technology,
including for the near-ultraviolet range, also served as a
useful resource. The introduction of high-speed, highaccuracy and highly efficient automated lens processing lines
to factories also played a significant role in improved
productivity. In 1993, the UIS system was launched with the
newly developed BX microscope series (see 4.7). The
following year, UIS systems for inverted biologicalmicroscopes and metallurgical/industrial microscopes was
released with the AX, IX and BXM series of microscopes.
These were highly regarded by users in Japan and overseas.

Olympus
UIS series
UPlanFlmechanicaltube
length= ∞parfocalizin
g distance= 45mmOlympus
UIS series
UPlanApomechanicaltube length=∞
parfocalizin
g distance= 45mmOlympus
UIS series
PlanApomechanicaltube length=∞
parfocalizin
g distance= 45mmFig. 7.29 Structure of Olympus UIS Objective Lenses 21)a) extract from the UPlanFl, UPlanApo and PlanApo seriesb) Structure and cross-sectional photograph of the PlanApo 60×oil
Systematic Survey on Optical Microscope Technology in Japan71

Figure 7.29 shows the structure of UIS objective lenses and across-sectional photograph of the PlanApo 60×oil. Figures
7.30 and 7.31 show photographs of the biological andmetallurgical/industrial series.

Meanwhile, Nikon kept up with the transition tomechanical tube length infinity correction by developing the
new CF & IC optical system for metallurgical/industrial
objective lenses in 1994, combining CF objective lenses with
infinity correction. The tube lens had a focal length of
200mm. With a higher NA and better resolving power andcontrast that the previous CF MPlan series, the newtechnology comprised the CF IC EPI Plan, the long-workingdistance CF IC EPI Plan ELWD and the super-long-workingdistance CF IC EPI Plan SLWD, as well as the bright/darkfield CF IC BD Plan and CF IC BD Plan ELWD series(Figure 7.32).

Fig. 7.30 Olympus UIS Objective Lenses (Biological) 21)a) Ach 10×, 20×, 40×, 60×, 100×oilb) Plan 10×, 20×, 40×, 60×, 100×oilc) UPlanFl 4×, 10×, 20×, 40×, 60×oil iris, 100× oil, 100×oil irisFig. 7.32 Nikon CF & IC Objective Lenses 22)d) PlanApo 1.25×, 2×, 40×, 60×oil, 100×oile) UPlanApo 4×, 10×, 20×, 20×oil, 40×, 40×oil, 60×, 100×oila) CF IC EPI Plan 5×, 10×, 20×, 50×, 100×f) LCPlanFl 20×, 40×, S-40×, 60×cb) CF IC EPI Plan ELWD 20×, 50×, 100×c) CF IC EPI Plan SLWD 10×, 20×, 50×, 100×d) CF IC BD Plan 5×, 10×, 20×, 50×, 100×e) CF IC BD Plan ELWD 20×, 50×, 100×f) CF IC EPI PlanApo/CF IC BD PlanApo 150×

Nikon also developed the new CFI60 optical system, withfully redesigned biological and metallurgical/industrial
objective lenses. The company announced the system in 1996
with the new Eclipse microscope series. Designed withimproved specifications and performance, the major featuresof the system included the biological objective lenses also
having infinity corrected mechanical tube length, theparfocalizing distance lengthening from the previous 45mm
to 60mm and the revolving nosepiece mounting threadchanging from RMS to M25. Table 7.3 compares the
specifications of NCF series (Plan and PlanApo) and CFI60
series (Plan Fluor and PlanApo) biological objective lenses.
The working distance (WD) clearly increases at low andmedium magnification.

Fig. 7.31 Olympus UIS Objective Lenses(Metallurgical/Industrial) 21)a) MPlan 5×, 10×, 20×, 50×, 100×b) MPlan-BD 5×, 10×, 20×, 50×, 100×c) UMPlanFl 5×, 10×, 20×, 50×, 100×d) UMPlanFl-BD 5×, 10×, 20×, 50×, 100×e) LMPlanFl 20×, 50×, 100×f) LMPlanFl-BD 20×, 50×, 100×g) LMPlanApo(-BD) 250×

Table 7.3 Comparison of Nikon Biological Objective Lens CFI60 and NCF Series Specifications 22)

NCF series
CFI60
series

72

4×
0.13
16.22
0.13
17.1

10×
0.30
9.22
0.30
16.0

Plan (Fluor) series
20× 40× 60×0.50 0.70
1.78 0.61
0.50 0.75 0.85
2.10 0.66 0.30

100×oil
1.25
0.16
1.30
0.16

2×
0.05
5.80
0.10
8.50

4×
0.20
15.0
0.20
20.0

10×
0.45
2.75
0.45
4.00

PlanApo series
20× 40× 60×0.75 0.95
0.64 0.13
0.75 0.95 0.95
1.00 0.14 0.15

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. March

60×oil
1.40
0.17
1.40
0.13

100×oil
1.40
0.1
1.40
0.13

Figure 7.33 shows photographs of the main lineup of the
CFI60 series.

Fig. 7.33 Nikon CFI60 Objective Lens (Biological) 22)

In 2012, Nikon launched the industrial CFI60-2 objective
lens series using its own phase Fresnel lens technology, witheven lower chromatic aberration and longer working distance34). The phase Fresnel lens is a type of diffractive opticalelement (DOE) with negative dispersion properties (forconvex lenses, the shorter the wavelength, the longer the
focal length), unlike regular refracting lenses. This
combination makes it possible to offset color shift, thereby
achieving powerful correction of chromatic aberration. The
CFI60-2 objective lens series comprises the long-workingdistance TU Plan EPI/BD ELWD, the super-long-workingdistance T Plan EPI SLWD, the high-end long-workingdistance TU Plan Apo EPI/BD, the standard design TU Plan
Fluor EPI/BD, the very low magnification T Plan EPI and thepolarized light TU Plan Fluor EPI P, all with phase Fresnel
lenses. Figure 7.35 shows photographs of the CFI60-2 series.

a) CFI Plan Apo 20×, 2×, 40×, 4×, 60×oil, 10×, 100×oilb) CFI Plan Fluor 4×, 40×, 10×, 60×, 20×, 100×oilc) CFI Plan 1×, 2×, 4×, 40×, 10×, 100×oil, 20×d) CFI Ach 4×, 40×, 10×, 100×oil, 20×e) CFI S Fluor 10×, 20×, 40×, 40×oil

Olympus revised the UIS optical system in 2004 anddeveloped the new UIS2 optical system, launched with thePower BX Plus upright biological microscope and the PowerIX Plus inverted biological microscope. The main features
are given below.
1) Improved fluorescence S/N ratio through new lenscoating technology and careful selection of glass.
2) High-end objective lens UPLSAPO series offers
advanced correction of chromatic aberration from 430nm
visible light to 1000nm near-infrared, as well as
improved transmittance from near-ultraviolet to nearinfrared, suitable for cutting-edge applications such as
multicolor fluorescence microscopy.
3) Uniform illumination system and more accurate color
representation of the specimen for digital imaging.
4) Environmentally friendly, with all glass material used in
the optical system made from eco glass, free from lead,arsenic and other toxic substances.
Figure 7.34 shows a photograph of the UIS2 series.

Fig. 7.35 Nikon CFI60-2 Objective Lensa) T Plan 1×, 2×b) T Plan SLWD 10×, 20×, 50×, 100×c) TU Plan Fluor 5×, 10×, 20×, 50×, 100×d) TU Plan Apo 50×, 100×, 150×

7.4.5
Objective Lenses with Special Characteristics
Thus far, this chapter has discussed standard objective
lenses of various companies. However, as design technology
has progressed, other objective lenses with various
specifications and characteristics have been developed tomeet a diverse range of needs. Below is a discussion of someof these lenses with special characteristics.
(1) Very Low Magnification Objective Lenses
While biological microscopes usually have magnificationsof 4× or higher, some very low magnification objectives
lenses have been developed with magnifications of 2× orlower to allow viewing and recording of specimens at a wider
field. These lenses have a longer focal length, making it
harder to design them with the same parfocalizing distance asother magnification levels. For example, the Olympus Plan
1.3× had a parfocalizing distance of 60.6mm instead of theFig. 7.34 Olympus UIS2 Objective Lens 21)a) UPlan SApo 4×, 10×, 20×, 20×oil, 40×, 60×w, 60×oil, 100×oilb) PlanApo N 1.25×, 2×, 60×oil, 60×oil SC

usual 36.65mm, which made it less user-friendly. In 1975,
Tiyoda became the first company in Japan to achieve successwith very low magnification objective lens parfocalizingc) UPlanFL N 4×, 10×, 20×, 40×, 60×oil, 100×oil

distance, announcing the Plan 1× objective lens (NA 0.035,d) Plan N 2×, 4×, 10×, 20×, 40×, 50×oil, 100×oil

WD 1.6mm) with a field number of 26.5 together with its
Systematic Survey on Optical Microscope Technology in Japan73

new MT-B microscope. In 1976, Nippon Kogaku included

viewing became more commonplace, primarily in the

the CF Plan 1× to its lineup of CF objective lenses. Olympus

industrial inspection market. This need was met by the CF

launched the SPlanFl 1× with its LB series and the PlanApo

MPlanApo 200× (NA 0.95, WD 0.2mm) and the UIS series

1.25× (NA 0.04, WD 5.1mm) with its UIS series. Figure 7.36

LMPlanApo 250× (NA 0.90, WD 0.80mm, Figure 7.38).

shows the structure of the SPlanFl 1×. As the figure shows, alens with a focal length of 138mm has been made to fit
within a parfocalizing distance of 45mm and the exit pupil(back focal point) must fit on the same mounting surface as
lenses of other magnifications. This is a special type of lensmade up of a convex lens group, a concave lens group andanother convex lens group. Nikon developed the Macro 0.5×
objective lens for its CFI series (NA 0.025, WD 7.0mm,
Figure 7.37; even smaller than the other figure). This system
had an additional lens (the lens at the top of the figure)separate from the objective lens, while the objective lensitself had a larger parfocalizing distance of 60mm, which
made the design possible, although the specifications of a
400mm combined focal length and a φ50mm microscope
field of view are not seen anywhere else in the world.

Fig. 7.38 Olympus LMPlanApo250× 21)(3) Ultra-Long Working Distance Objective Lenses
Microscope objective lens working distance (WD)generally gets shorter as magnification increases, although
the longer the working distance, the more convenient andreliable it is to use in terms of specimen visibility andconcerns over the objective lens colliding with the specimen.
Accordingly, long WD objective lenses have been added to
product lineups, especially for metallurgical/industrial
microscopes and culture microscopes. These lenses usually
have L or LWD in the name. Figure 7.39 shows the structureof an ultra-long WD objective lens. While the NA of 0.45 is
low for 50×, the 15mm WD is around 4.2 times longer than
the focal length. The lens is made with many ED glasses, as
the front lens inevitably increases the beam height, making it
susceptible to chromatic aberration. The back lenses include astrong concave power lens. This example shows aparfocalizing distance of 45mm, although long WD objective
lens design is easier for objective lenses with parfocalizing
distances of 60mm or 95mm, mentioned previously.

Fig. 7.36 Olympus SPlanFl
1×

21)

Fig. 7.37 Nikon CFI Macro
Plan 0.5× 22)(2) Ultra-High Magnification Objective Lenses
As microscope resolving power is mainly determined by
the objective lens NA, indiscriminately increasing themagnification does not necessarily make it possible to view
the specimen in high detail. Generally, the effective range ofthe total magnification M is between 500NA and 1000NA.
Magnification beyond this is called empty magnification (see2.5). With the highest magnification objective lenses
achieving 100×, or at best 160×, the need arose for an easierFig. 7.39 Olympus SLMPlan 50× 21)

way to view higher levels of magnification as monitor

74

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. March

(4) High Numerical Aperture (NA) Objective Lenses

Since the objective lens is stationary, it has a relatively low

Since the immersion oil used for increasing NA has amagnification and high NA, and changes in magnification are

refractive index ne of 1.518, for a long time the maximum

carried out using a separate magnification changing device.

limits for increasing objective lens aperture NA in opticalFigure 7.41 shows the exterior view of a Nikon CFI75 LWD

design were thought to be 1.30-1.40. However, recent

16× W (NA 0.80, WD 3.0mm), with a unique parfocalizing

developments include the Olympus PlanApo N60×oil (NAdistance of 75mm.

1.42) in the UIS2 series (2004) and the Nikon 100×oil H (NA1.45) in the CFI PlanApoλ series (2011). With the emergenceof total internal reflection fluorescence microscopy (TIRF,
see 5.7.3) increasing the demand for objective lenses to havea high NA, manufacturers began to sacrifice image flatness
for high NA in their high magnification objective lenses.
Nikon brought out the CFI Apo TIRF 60×oil and 100×oil(both NA 1.49), while Olympus brought out the Apo N
60×oil TIRF, 100×oil TIRF (both NNA 1.49) and the 150×oil
TIRF (NA 1.45), as well as the Apo 100×oil HR (NA 1.65,
Figure 7.40) and Apo N 100×Hoil TIRF (NA 1.70), whichused special oil (nd = 1.780, νd = 19.1) and special coverglasses.

Fig. 7.41 Nikon CFI75 LWD 16× W 22)(6) Infrared Objective Lenses
The Si, GaAs and ceramic parts of semiconductors aretransparent under infrared light with a wavelength over 1μm.
This means that infrared light microscopy can be used fornon-destructive viewing of IC patterns from the reverse sideof chips (the reverse side of the silicon substrate needs to be
ground), internal viewing of MEMS, inspecting ceramics prefiring and various other applications, with the result shown
on a TV monitor. Designed to take non-microscope viewing
into account as well, infrared objective lenses correctaberrations in the range from visible to near-infrared(wavelength around 2μm) and ensure broad-spectrum
Fig. 7.40 Olympus Apo 100 ×oil HR 21)(5) Water Immersion Objective Lenses
Objective lenses have long been used with water as theimmersion liquid (see 7.1.1). In recent years, this has again
resurged for viewing cells in culture fluid. E. Neher and B.
Sakmann, developers of one such electrophysiologicaltransmittance. Infrared objective lenses are also usedapplications such as femtosecond lasers and laser repair ofsemiconductor circuits and liquid crystal substrates by YAG
laser (1064nm). Products include the Olympus
ULWDMIRPlan series (IC series) and LMPlan-IR series(UIS series), the Nikon LRPlanApo-NIR series and the
Mitutoyo MPlanApo NIR series.

technique, the patch clamp, were awarded the Nobel Prize inPhysiology or Medicine in 1991, bringing neuroscience andelectrophysiology into the spotlight. Water immersion
objective lenses also played an important role in viewing andhandling culture cells in new areas of technology, such as
genetic analysis and monomolecular imaging. An uprightmicroscope with a special stationary stage is used for this.
Unlike ordinary objective lenses, the water immersion area isinsulated, and the lens has longer working distance and anangled tip to make manipulation easier. High magnification
objective lenses have a correction collar mechanism tocorrect aberration relative to the depth of the immersed cells.

(7) Deep Ultraviolet Objective Lenses
Various companies have worked on developing ultraviolet
objective lenses for viewing specimens in the ultraviolet
range and for achieving higher resolution images. Ordinary
optical glass, even fluoro-crown glass, with high ultraviolet
transmittance, allows only wavelengths as low as 300nm. In
deep ultraviolet, lower than 300nm, the optical materials arelimited to fluorite, quartz etc. In 1959, Zeiss launched the
Ultrafluar series, with high spectrum transmittance fromaround 240nm in the deep ultraviolet range through to near
Systematic Survey on Optical Microscope Technology in Japan75

infrared. Used in biological microscopes with glycerol as theor field lens, collecting the light rays from the objective lens

immersion liquid (ne=1.450, ve=58), these were adopted forand the back lens, or eye lens, enlarging the image. This two-board wavelength range spectrum photometry andlens system has long been used, as a single-lens system

fluorescence microscopy. Deep ultraviolet objective lenses

requires a larger lens diameter for a larger field. The Huygens

for high resolution industrial use include a special 100× lens

eyepiece (Figure 7.43), invented by Dutch physicist C.

(NA 0.9, WD 0.42mm, λ 266nm) in the LU2000-DUV laser

Huygens in 1703, uses simple lenses for the field lens andmicroscope developed by Nikon in 1998 for use in a wafer

eye lens, with the objective lens image position between theinspection system, allowing contactless, non-destructive, real

two lenses. The Ramsden eyepiece (Figure 7.44), invented bytime inspection and evaluation at an ultra-high resolution of

British J. Ramsden in 1783, has the image position on the

0.1μm L/S. In 2001, Olympus developed the MApo 10× -objective lens side. The latter has the advantage of easily

248NC (NA 0.90, WD 0.2mm, λ 248nm, Figure 7.42) for

being able to insert graticules with crosshairs, graduation

DUV, as well as a DUV confocal unit. Both lenses werescales at the objective lens image position. In 1849, C.

extremely complicated optical systems to manufacture, madeKellner of Germany (see 3.4) invented the Kellner eyepiece

up of groups of single lenses of synthetic fluorite and(Figure 7.45) by replacing the eye lens in the Ramsden lens

synthetic quartz without using cement lenses, requiring very

with an achromatic lens to improve chromatic aberration. Ashigh accuracy in processing and assembly.

these eyepieces had relatively low field numbers, indicating anarrow field of view, and a low eyepoint height (the eye
position of the viewer, shown in the figures as ●EP), they
were used less frequently as microscopes became moreadvanced.

Fig. 7.43 Huygens Eyepiece

Fig. 7.42 Olympus MApo100× -248NC 21)(8) Other Lenses
There are many other microscope objective lenses besides
the above, each designed for a different purpose. Other types

Fig. 7.44 Ramsden Eyepieceof lenses include interference objective lenses thatincorporate two-beam or multi-beam interferometers,
reflection objective lenses, made up only of reflective
surfaces and with no chromatic aberration, and measuring
microscope objective lenses that fully correct distortion. The
history and technological development of each of these has
been omitted from this report due to space and time
constraints.

7.5 Eyepiece Development in JapanThe eyepiece (see 2.6.3) is the lens that enlarges the image
from the microscope, telescope or binocular objective lens.
This is made up of two groups of lenses, with the front lens,76

Fig. 7.45 Kellner Eyepiece

In 1860, Austrian optical instrument maker S. Plößl
invented the Plößl eyepiece, an improved version of the
Kellner eyepiece with four elements in two groups (Figure7.46). In 1880, Abbe invented the Abbe eyepiece, made up ofa triplet lens and a single lens (Figure 7.47). This eyepiececorrects aberration relatively well and is known as theorthoscopic eyepiece. It is still used today, as it can have a

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. Marchhigh field number and be combined with high-end objective
lenses, and has a high eyepoint, which makes it easy to use.

7.51). All of these eyepieces had quite complex lensstructures to correct various aberrations.

In 1918, H. Erfle of Zeiss invented an eyepiece with a wide
field of view for military binoculars (Figure 7.48). An
improved version of the Plößl eyepiece with an additional
single (or doublet) lens, this eyepiece has also been widelyused in microscopes.

Fig. 7.49 SW 10× 21)

Fig. 7.46 Plößl Eyepiece

Fig. 7.50 WH 10× 21)

Fig. 7.47 Abbe Eyepiece

Fig. 7.51 SWH 10× 21)

Fig. 7.48 Erfle Eyepiece

Before and after the war, most Japanese microscope
eyepieces were the Huygens, Ramsden or Kellner types
described above. As development progressed on Plan
objective lenses, higher quality eyepieces with higher field
numbers began to emerge. Standard 10× eyepieces included
the Olympus WF10× (Abbe type), with a high eyepoint andfield number of 18, and the Nippon Kogaku HKW10× (Plößltype), both of which appeared in the 1960s. In an ordinary
viewing tube, the sleeve that held the eyepiece had a standard
φ23.2 inner diameter. Olympus developed a new φ30 superwide field viewing tube and used it in the EH and FH stands
with the super-wide field eyepieces SW7× (field number 29)
and SW10× (field number 26.5, Figure 7.49). In the late1970s, improvements were made to eyepieces as new opticalsystems were adopted. Nikon developed the CF eyepieces,including the ultra-wide field UW10× with a field number of
26.5, while Olympus developed the WHK10× (Erfle type)with a field number of 20 for the new LB optical system. On
completion of the UIS optical system, the company
developed the WH10× with a field number of 22 (Figure7.50) and the SWH10× with a field number of 26.5 (Figure

Improvements to eyepieces have continued in this mannerand objective lenses continue to progress in keeping with new
microscope technology. It can only be imagined what new
developments will emerge in the future. While microscope
images may never be visible to the naked eye, there are highhopes for new concept eyepieces, such as combining withdigital display technology.

References
1) Tsuruta T.: History of Optical Technology, New Optical
Technology Handbook, Asakura Publishing Co., Ltd.,
2002, pp. 1-81
2) Bögehold H.: Das Optische System des Mikroskops, Veb
Verlag Technik Berlin, 1958, pp.77-100
3) Bögehold H.: Microscope objective, USP No.2, 206,155,
19384) Ikegami S.: Round-Table Discussion “The Past andPresent of Microscopes”: Nihon no Kenbikyō
Seizōgaisha no Kōgaku Sekkei Gijutsu [Optical Design
Technologies of Japanese Microscope Manufacturers](1910-1936), Journal of History of Science, Japan, Vol.
270, 2014, pp. 227-230

Systematic Survey on Optical Microscope Technology in Japan77

5) Tiyoda Kenbikyō no Rekishi [History of Tiyoda
Microscopes], Sakura Seiki, 1994, pp. 66-70
6) 50-nen no Ayumi [A 50-Year History], Olympus OpticalCo., Ltd., 1969, pp. 67-72
7) Hikari to Mikuro to Tomoni - Nikon 75-nen-shi [Light

22) Supplied by Nikon Corporation
23) Ushida K.: Atarashii Kenbikyō Kōgaku-kei [NewMicroscope Optical Systems], Japanese Journal of
Optics, Vol. 10 No. 5, 1981.10, pp. 326-333
24) Shimizu Y. and Takenaka H.: Microscope Objectiveand Micro Together: A 75-year History of Nikon], 1993,

Design, Advances in Optical and Electron Microscopy

pp. 19-20, 40-44, p. 117, p. 181

Vol.14, Academic Press, 1994, pp.249-334

8) Tsuruta T.: Kōgaku Sekkei Kotohajime [The Beginning25) Matsubara M.: Saikin no Kenbikyō Taibutsu Renzu ni

of Optical Design], No. 5: Light Pencils, Newtsuite [The Latest Microscope Objective Lenses], Optical

Technology Communications, 1997, pp. 95-130

and Electro-Optical Engineering Contact, Vol. 16 No. 3,9) Conrady A. E.: Applied Optics and Optical Design, Part

1978, pp. 24-32

1, Oxford Univ. Press, 1929 Part 2, Dover N.Y., 1958

26) Matsubara M.: Kenbikyō no Chishiki – Mugen’en Hosei

10) Berek M.: Grundlagen der praktischen Optik; Analyse

Kenbikyō Kōgaku-kei [Microscope Knowledge: Infinity-

und Synthese optischer Systems, Berlin, 1930

Corrected Microscope Optical Systems], O plus E, Dec.

Japanese translation Miyake K.: Renzu Sekkei no Genri

1981, pp. 83-87[Lens Design Principles], Kodansha, 1970
11) Ashida S.: Renzu no Sekkei to Sokutei [Lens Design andMeasurement], Kawade Shobo, 1940
12) Suzuki T.: Proc. Jpn. Acad. 27 (1951) No.4, p.179, p.184
13) Suzuki T.: Kōgaku Renzu Jidō Sekkei no Hatten[Development of Automatic Lens Design], Applied
Physics, Vol. 51 No.5, 1982, pp. 508-512
14) Kurokawa T.: Garasu no Gijutsu-shi [History of Glass
Technology], Agne Gijutsu Center, 2005, pp. 151-196
15) Supplied by Schott Japan Corporation
16) Supplied by Ohara Inc.

27) Nakamura T., Arisawa K.: Chō Chōsadō Kyori wo motsu
Kenbikyō Kōgaku-kei to sono Tenkai [Ultra-Long
Working Distance Microscope Optical System and its
Development], Optical and Electro-Optical Engineering
Contact, Vol. 29 No. 3, 1991, pp. 360-368
28) Arisawa K., Nakamura T.: Atarashii Sekkei ni yoru
Kenbikyō no Kōgaku-kei [Newly Designed Microscope
Optical Systems], O plus E, Oct. 1993, pp. 94-97
29) Supplied by Mitutoyo Corporation30) Muchel F.: “ICS”-A New Principle in Optics, ZEISSInformation, Oberkochen, 30 20, 1989/1990

17) Kusetsu jūsan-nen Orinpasu Kenbikyō/Gentō-ki/Eisha-ki31) Euteneuer F., Müller-Rentz A und Schade K. H.:

no Keireki [Thirteen Hard Years: The Career History of

DELTA – das neue Mikroskop-Optiksystem,

Olympus Microscopes, Slides and Projectors], Takachiho

Mitteilungen für Wissenschaft und Technik Bd. X. Nr.4,

Works, Co., Ltd., 1932, pp. 5-12
18) Supplied by Hamano Microscope Co., Ltd.
19) Supplied by Olympus Museum of Technology andHistory Zuikodo20) Claussen H. C.: Microscope Objectives with Plano-

1992, S.114-122
32) Nagano C.: New Microscope Optical Systems: UIS,OMR (Olympus Microscope Review), No. 22, 1993, pp.
34-3833) Nagano C.: Saikin no Seibutsu Kenbikyō Kōgaku-kei –Correction, Applied Optics, Vol.3, No.9 1964, pp.993-

Mugen’en Hosei Kōgaku-kei to Shisutemu-ka [The1003

Latest Biological Optical Systems: Infinity-Corrected21) Supplied by Olympus Corporation

Optics and Systematization], Optical and Electro-OpticalEngineering Contact, Vol. 31, No.12, 1993, pp. 705-712
34) Yoshida M.: Proceedings from the 38th Optical
Symposium, Vol. 38, Jun. 2013, pp. 85-88

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8

The Latest Optical Microscopes

As discussed in previous chapters, long and tireless efforts

A confocal optical system can be arranged by having a

have been made to improve the specifications andperformance of optical microscopes through the mastery of

pinhole at a conjugated position with the spot on thespecimen when focusing (Figure 8.2). Images created in theseincreasingly advanced optical technology. This has resulted
in extremely high-level optical instruments, and it was

confocal optical systems have the following distinguishing
characteristics compared to ordinary microscope images.

believed that it would be difficult to extend much further
beyond the bounds of existing designs and production

1) Since the light from outside of the focal position is
excluded, it is possible to optically section thicktechnology. Accordingly, little was expected in terms ofprogress on electron microscopes and various probe

specimens. Processing then overlapping these images canform a clear, three-dimensional image.

microscopes. However, in the late 1980s, the laser scanningmicroscope and other new types of optical microscopes2) Light outside of the specimen spot, a cause of flares inordinary microscopes, is cut out completely, allowing abegan to emerge. These once again drew microscopes into
the limelight, with the special characteristic of being able tovery high contrast image to be obtained.
3) Making the pinhole very small can theoretically increase

view live specimens. This chapter discusses the rapid
development and popularization of laser scanning

the resolving power by 1.4× that of ordinary
microscopes.

microscopes, multiphoton excitation microscopes and superresolution microscopes. Each of these is still developing interms of theoretical research, technological development andapplication. The hope is that these will be the subject of their

X scanner
Beam expanderLaser

own systematic survey of technology in the future.

Detector

8.1 The Laser Scanning Microscope (LSM) 1) 2)
The laser, one of the greatest inventions of the 20th
century, was invented in the 1960s. Due to its distinguishing
characteristics of coherent phases, superior directionality andinferior image glaring with interference noise. Instead, lasers
are used in microscopes to form images by rapidly scanning a

Dichroic mirror

ConfocalpinholePupil projection
lens

Eyepiece

Detector

Epifluorescenceillumination
systemTube lensSignal processor

Frame memory

Controller

Monitorto X-Yscanners

Objective lensSpecimen
Condenser lensTransmitted lightillumination system

monochromaticity, it has been used in various fields,
including imaging, information, communication, measuring,
medicine and processing. Using a laser beam as a microscope
illumination source on its own would only produce an

Y scanner
Pupil relay lensTransmitted
light detector

to Signal
processor

Fig. 8.1 Basic Optical System of a Laser Scanning
Microscope 1)

laser spot on the specimen. Figure 8.1 shows the basic opticalsystem of a laser scanning microscope. The laser beam passes
Incident laser
Light detector

through a beam expander and expands in diameter, thenconverges again after passing through two scanners (such as a
mirror galvanometer) in the X and Y directions. The lightpasses through the objective lens and forms a spot on thespecimen. The light reflected or fluoresced from thespecimen travels back through the incident light path of the

Objective lenslaser and is transmitted into a detector system by a half mirror
or dichroic mirror. The signal is processed, and an image is

Focus
position

displayed on a monitor. The laser beam transmitted by the
specimen passes through a condenser lens and into a detector.
The combined use of a Nomarski prism can produce a
differential interference contrast image for non-stained
specimens.

ConfocalpinholeFig. 8.2 Confocal Optical System 1)

The basic principle of confocal microscopes that havepinholes on the illumination side and the detection side to
manipulate the specimen was invented by MIT graduate M.
Minsky in 1957. In 1966, Czech scientist M. Petráň invented
Systematic Survey on Optical Microscope Technology in Japan79

the multi-pinhole microscope. Using an extension of the
Nipkow disk principle for mechanical television image
scanning, this microscope makes it possible to view theconfocal image with the naked eye or by CCD by rapid
rotation. This idea was first applied to lasers for laser
scanning microscopes by P. Davidovits and A. M. D. Egger
in 1969. Theoretical research on LSMs and confocal opticalsystems was propelled by British scientists C. J. R. Sheppard
and T. Wilson around 1977-1980. As the advantages of theconfocal laser scanning microscope (CLSM) would be

Fig. 8.3

Olympus LSM-

Fig. 8.4 Nikon RCM8000 4)

GB200 3)utilized best in fluorescence microscopes in medicine andbiology, developments were concentrated on fluorescencemicroscopes, with various combinations of fluorochromes
and lasers being developed. The industrial LSM had the same
basic structure, but had a micro electro mechanical system(MEMS) built into the XY scanner to make it more compact.
It has been widely used for high-resolution three-dimensional
measuring instruments.
Commercialization of the LSM started in 1982 with Zeiss

Fig. 8.5 Olympus FV1000 3)

announcing an LSM with a He-Ne laser and galvanometer
mirror scanning. In 1985, Bio-Rad started marketing the
MRC-500, jointly developed with Cambridge University. The
same year, NJS Corporation (now Lasertec Corporation)
announced a color LSM, marketed from 1986 as the ILM
series (industrial). Olympus released the biological LSM-GB(upright) and LSM-GI (inverted) in 1990. These machines
had an image memory of 640×480 pixels. An improved

Fig. 8.6 Olympus FV10i 3)

model, the LSM-GB200, was launched in 1992 (Figure 8.3).
Nikon released its first LSM in 1993, the RCM8000 (Figure8.4). Yokogawa Electric entered the biotechnology arena in
1996 with the launch of the CSU series CLSM scanning unit,
using a rapidly rotating multi-pinhole disk. The same year,
Olympus brought out the new Fluoview (FV) LSM, followedby the FV300/500 in 1999, the FV1000 in 2004 (Figure 8.5),
the box-shaped FV10i in 2008 (Figure 8.6) and the FV3000
in 2016. With each model, the company has continued to add
improvements function and performance. Nikon launched theFig. 8.7 Nikon C2+ 4)

Digital Eclipse C1 confocal system in 2002, followed by theC1si real spectral imaging LSM system with an added
spectral function in 2005, the functionally-improved A1/A1R
CLSM system in 2008 and the C2+/C2si+ in 2011 (Figure8.7). Major Japanese industrial laser scanning microscopes
include the Olympus OLS (LEXT) series (Figure 8.8), theKeyence VK-X series and the Lasertec Optelics.

Fig. 8.8 Olympus LEXT4000 3)

80

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. March

8.2 The Multi Photon Excitation Laser Scanning
Microscope (MPE LSM) 5) 6) 7)
When fluorescent molecules are irradiated with an
excitation light, if two excitation photons are absorbed at thesame time (two-photon excitation), the energy doubles, aphenomenon similar to an excitation light with a half
wavelength. Where this occurs with more than two photons,
it is called multi photon excitation (MPE). This process only
occurs very rarely in the natural world, although theprobability can be increased by increasing the photon density
to very high levels. Two-photon excitation microscopes use afemtosecond (10-15) ultra-short pulse laser for an illumination
source to prevent damage to the specimen from the highphoton density. When a laser beam is concentrated onto the
focal position of an objective lens, it automatically produces
a confocal effect as two-photon excitation occurs in that
position only. The image is formulated by scanning with X
and Y scanners in the same way as a regular LSM, but there
is no fluorescence loss as no confocal pinhole is required(Figure 8.9). Fluorescence detection near the image of theobjective lens detects more fluorescence, including scatteredfluorescence. Since the excitation wavelength can be twice as
long, a near-infrared laser (Ti:sapphire) is used as it produces
better biological tissues transparency than visible light or
ultraviolet lasers. This allows microscope imaging to depthsof several hundred μm to several mm below the surface of thetissue without causing damage. As a result, it is possible toview neural activity and blood flow in living animals. Twophoton excitation microscopes are often structured like aconfocal LSM, although they have a broader wavelength
range than one-photon excitation microscopes, so theobjective lenses need to be high performance lenses with hightransmittance across the wavelength range and havechromatic aberration properly corrected, as well as a long
working distance to achieve deep specimen viewing. Insteadof water, the immersion liquid is usually either silicone oil, as
it has a closer refractive index to biological cells, or a special
solution to make the tissue more transparent. Figure 8.10
shows an example of a special multi-photon excitation
objective lens (Olympus XPlan N 25× SVMP, NA 1.0 WD
4mm, silicone immersion). Japanese MPE LSMs date back to
2006, with the launch of the FV1000-MPE by Olympus(Figure 8.11) and the A1R-MP by Nikon (Figure 8.12).
Photomultiplier
PinholeVisible /ultraviolet laser

No pinhole needed

Near infrared ultrashort pulse laser

Focal position

Fig. 8.9 Comparison of LSM and MPE LSM Structures 1)

Fig 8.10 Olympus MPE Specialized Objective andConfiguration 3)

Fig. 8.11 Olympus FV1000-MPE 3)

Fig. 8.12 Nikon AIR-MP 4)

8.3 The Super Resolution Microscope (SRM) 8)
9) 10) 11)

Super resolution in optical microscope is an opticalmethod of producing a resolution higher than the resolution
limit (around 200nm) given by the 2.7 formula (see 2.5)
taken from Abbe’s imaging theory. Electron microscopes use
electron beams with wavelengths far shorter than light andproduce higher resolutions than optical microscopes.
However, there are many issues with their use in bioresearch,such as being unable to produce images of living cells andincapable of multi-staining. Accordingly, there has been ademand for a super resolution microscope with thetechnology to go beyond optical limits using light that is notharsh on organisms. New super resolution methods
developed to resolve this include PALM, STED and SIM.
Each of these targets fluorescence imaging. Developers E.
Betzig (USA), S. W. Hell (Germany) and W. E. Moerner
Systematic Survey on Optical Microscope Technology in Japan

81

(USA) were awarded the Nobel Prize in Chemistry in 2014.
The main features of each system are outlined below.
(1) Localization
Photo-activated localization microscopy (PALM) uses
strong excitation specific to certain fluorescent probes in a
specimen to illuminate certain molecules separately andlocate the center. Once the fluorescence fades out, excitation
is carried out again to find the center of a different molecule.
By repeating this process, it is possible to measure between
different points of light emission with an accuracy of around
10nm, making it possible to record the location of eachmolecule in the specimen and build up a fluorescent image
from their distribution. While the fluorescence fromindividual molecules is extremely faint, imaging is possibleusing total internal reflection fluorescence microscopy (see5.7) to suppress the background image significantly.
Stochastic optical reconstruction microscopy (STORM) is
another method of super resolution microscopy that uses asimilar optical system and analysis method.
(2) Stimulated Emission Depletion (STED)
Overlaying stimulated emission depletion laser beams(STED beams) with a toroidal intensity distribution at theexcitation laser focal point causes the excited fluorescentmolecules in the middle to emit light by natural emission andin the peripheral area by stimulated emission. The stimulated
emission has the same wavelength as the STED beam. Whenthe intensity is increased, the area of natural fluorescenceemission decreases. Cutting out the stimulated emission
wavelength can produce fluorescence emission with highresolution of several dozen nm.

(3) Structured Illumination Microscopy (SIM)The specimen is illuminated with excitation light that has afringe pattern (structured illumination). Images are captured
while changing the direction and phase of the fringe. The
images are then combined, processed and recompiled as ahigh-resolution image. The resolution can be twice as high asthat of a regular microscope. This system has the advantage
of being able to produce high-resolution images relatively
quickly using conventional fluorescent probes.
Leica was the first to commercialize a super resolution
microscope (STED) in 2007, followed by Zeiss (PALM) at
the end of 2009. Nikon also launched the N-SIM (Figure8.13) and the N-STORM (Figure 8.14) at the end of 2009, ina license agreement with the University of California andHarvard University, respectively. Olympus launched the FVOSR software module for spinning disk super resolution
microscopy (SDSRM), jointly developed in 2015 withRIKEN. The company integrated this software into the FV
series confocal LSM.

82

Super resolution microscope technology is still underdevelopment, with the expectation that it will be possible toview live specimens at higher resolutions. There are highhopes that these new optical microscopes will lead toamazing discoveries in life science in the near future.

Fig. 8.13 Nikon N-SIM 4)

Fig. 8.14 Nikon N-STORM 4)

References
1) Nagano C.: Kōgaku wo Chūshin to shita Kenbikyō no
Kiso [Microscope Fundamentals with a Focus on
Optics], Japan Microscope Manufacturers’ Association
website http://www.microscope.jp/knowledge/index.html(2016.12.20), supplied by Japan Microscope
Manufacturers’ Association
2) Kawata S. (ed.): Atarashii Kōgaku Kenbikyō Daiikkan
Rēza Kenbikyō no Riron to Jissai [New Optical
Microscopes Vol. 1: Laser Microscope Theory andPractice], Interdisciplinary Planning, 1995
3) Supplied by Olympus Corporation4) Supplied by Nikon Corporation
5) Miyawaki A.: Keikō Imējingu Kakumei [TheFluorescence Imaging Revolution], Cellular Engineering
Special Volume, Gakken Medical Shujunsha, 2010, pp.
227-234
6) Okubo Y., Iino M.: Nikōshi Reiki Kenbikyō [TwoPhoton Excitation Microscopes], Experimental Medicine
Special Volume: Staining and Bioengineering
Experiment Handbook, Yodosha, 2006, pp. 262-267
7) Nojima H. (ed.): Kenbikyō no Tsukaikata Nōto
[Notebook on How to Use a Microscope], 3rd Revision,
Yodosha, Apr. 2011, pp. 136-226
8) Fujita K.: Chō-Kaizō Kenbikyō no Shinten[Development of the Super-Resolution Microscope],
Biophysics and Physicobiology, Vol. 50 No. 4, 2010, pp.
174-179
9) Furuta A.: Saibō-nai no Seimei Genshō wo miru ChōKō-Kaizōdo no Keikō Kenbikyō no Kaihatsu[Development of the Super-Resolution Fluorescence
Microscope for Viewing Intracellular Life Phenomena],
Nikkei Science, Dec. 201410) Okada Y.: Raibuimējingu no tame no Chō-Kaizō
Kenbikyō [Super-Resolution Microscopes for Live
Imaging], Optical and Electro-Optical Engineering
Contact, Vol. 51 No. 4, 2013, pp. 4-1211) Nagai T.: Kaisetsu Genkai wo Koeta Chō-Kaizō Keikō
Kenbikyō [Super-Resolution Fluorescence Microscopes
Beyond the Diffraction Limit], Chemistry, Vol. 69 No.
12, 2014, pp. 21-26

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. March

9Conclusion and Discussion

It has been more than 420 years since the microscope wasinvented. Its development history includes the knowledge,
passion and perseverance of pioneers wanting to explore themicroscopic world. It has played a significant role indevelopments in medicine and other fields of science andindustry. The history of microscope development can bedivided into the following time periods, as shown in the flow
chart of optical microscope development in Appendix 3.
1) Dawn Era: From the emergence of the first microscopes
through to the early 19th century, scientific results fromcompound microscopes include R. Hooke’s publicationof “Micrographia” (1665) and A. Leeuwenhoek’s
discovery of microbes using a single-lens microscope(1673). Single-lens microscopes offered better
magnification and resolving power.
2) Performance Improvement Era: In the mid-19th century,
high-magnification objective lenses began to be
produced using combinations of achromatic lenses.
These compound microscopes far outdid single-lensmicroscopes in performance and operability. Researchbegan on objective lens theory and design. Polarized
light microscopes and reflected light microscopes
emerged at this time.
3) Theory/Technology Establishment Era: In the late 19th
century, E. Abbe of Germany established a microscope
imaging theory and a method of objective lens design by
ray tracing. Apochromatic lenses and the homogenous
immersion method reached completion, significantly
improving performance. Successive discoveries of
disease pathogens were made using microscopes during
this time, while German microscopes made by Zeiss andLeitz (now Leica) took a world-leading position. By theturn of the 20th century, German researchers had
produced a succession of microscopes with various
viewing methods still used today, such asstereomicroscopes, ultramicroscopes (dark fieldmicroscopes) and fluorescence microscopes.
4) Intense Pursuit Era: In the 20th century, impacted by twoworld wars, the microscope development environmentchanged drastically, with the development of lens designby computer and new types of glass, and the introductionof electronics technology. Japan started with zeroexperience in microscope production and steadily
improved its products. With several new optical systems
developed from the late 1970s onwards taking optical
microscope performance close to its upper limits, Japancame to rival Germany for global dominance.
5) New Optical Microscope Era: The emergence ofconfocal laser scanning microscopes in the late 1980s
drew attention to optical microscopes, once thought to belimited, as essential tools in bioimaging and othercutting-edge fields of research. Progress has been madeon multi photon excitation laser scanning microscopes
and super resolution microscopes, with further
development expected.

This report discusses Japanese microscope technology,
especially optical technology, in the context of optical
microscope history, in the light of above. In the late Meiji
Period, the dawning era of the optical industry, the pioneersof Japanese microscope industry made earnest efforts toduplicate German microscopes by dismantling them,measuring them and producing their own. Replicating theperformance of objective lenses was a near impossible task,
requiring high-precision machining and assembly, while notknowing the type of glass used. These challenges were
surmounted with ardor and true artisan spirit, and the “M &Katera” microscope was launched in 1914, laying thefoundation for the Japanese microscope industry that
followed. Takachiho Works (now Olympus) was establishedin 1919 and went on to complete the high-end apochromatic
objective lens in 1934. This ground-breaking achievement
demonstrates the level of growth in the Japanese opticalindustry at this time. In 1917, Nippon Kogaku (Japan Optical,
now Nikon) had the best optical technology in Japan and wasdeveloping and producing all kinds of optical instruments.
Thus we see that the basic technology in the Japanese opticalindustry was already at world standard before the war. Afterthe war, as the industrial world transitioned to peacetime
industries, the optical instruments industry came into fullbloom. The postwar rebuild of the microscope industry began
by reviving prewar microscope models, accompanied byresearch and standardization initiatives by industry,
government and academia. Olympus and Tiyoda Optical(formerly M & Katera) completed their own phase contrast
microscopes, prototyped by the Germans during the war. This
was a particularly noteworthy achievement, given the poor
development conditions following the war. Japanese
microscopes were being produced by Tiyoda Optical,
Olympus, Nikon and many other manufacturers. These
companies were steadily and reliably growing morecompetent in their development and production capabilities,
and the products being developed were becoming moreadvanced and higher quality. As a result, production
increased to meet the steadily growing domestic demand as
well as the growing number of exports to the West and otherregions overseas. Japan’s global reputation for quality, value
and service was growing. In the 1950s, companies began
launching system microscopes with different model units,
such as the Nikon S series and the Olympus E series. The
1960s saw the development of high-end universal
photography microscopes, such as the Tiyoda Polyphoto, theOlympus Photomax and Vanox and the Nikon Apophot.
Differential interference contrast, epifluorescence,
modulation contrast and other new viewing methods wereincorporated, and systems began to catch up with those of theworld-leading German microscopes. The quality of Japanese
optical microscopes started taking great strides forward in thelate 1970s. Central to this was the development of new
objective lenses and optical systems, with overall microscope
systems improving to match. In 1976, Nikon launched the
Systematic Survey on Optical Microscope Technology in Japan83

new CF series optical system and new V series microscope,
followed by the X and Y series in 1978. Olympus brought out
the new LB series optical system in 1978, followed by theBH2 series in 1980, the IC series industrial microscope
optical system in 1981 and the New Vanox AH2 in 1983. In
1985, Nikon added the new, high-spec NCF series opticalsystem to its lineup. German company Zeiss announced the
new ICS infinity-corrected optical system and the new Axio
series microscope in 1986, while Leitz (Leica) announcing
the Delta optical system and new DM series microscope in
1992. Olympus responded with the new UIS infinitycorrected optical system and the BX, AX and IX in 19931994, and Nikon announced the new CFI60 optical system
and Eclipse series in 1996. These four companies from Japan
and Germany continue to compete for the top position in the
global optical microscope industry.
Throughout the development history of optical
microscopes, all kinds of optical theories and technologies
have emerged, each limited by the resolution limits of light.
Aware of this, some researchers believed that there was nofurther scope for optical microscope development, in contrast
to electron microscopes or probe microscopes. However, asphase contrast and differential interference contrast made it
possible to observe live cells directly and the emergence of
new fluorochromes and fluorescent proteins meant
fluorescence microscopes had a central role in immunology,
DNA, neurology and molecular biology, interest in optical
microscopes grew once more. This was spurred on all themore by the emergence of laser scanning microscopes in thelate 1980s. Confocal laser scanning microscopy wasparticularly effective and combined with fluorescencemicroscopy to become an essential part of cutting-edge
bioimaging research. With developments being made in multi
photon excitation laser scanning microscopes and superresolution microscopes, the importance of optical
microscopes can only be expected to increase in future.
Japan has thus come to rival Germany in leading the worldin the field of optical microscopes. How has the Japanese
optical microscope industry been able to develop to thispoint, having started out by replicating microscopes fromoverseas only 100 years before? This is undoubtedly due to
the Japanese people’s strong interest and adoration for optical
instruments and our aptitude for precision machining, as well
as official recognition of the importance of these opticaldevices through national policy. Domestic production of
optical glass, independent development of lens design
software, technology development and standardization
through postwar collaboration between industry, government
and academia, as well as various other concurrent
developments in infrastructure, have been important elements
as well. The urge to compete with Germany and challenge its
revered position, as well as development rivalry between
Tiyoda, Olympus, Nikon and other Japanese manufacturers,
were essential to the development of the Japanese optical
microscope. On top of this, forward progress in medical andbioscience research and all kinds of industry areas meant
strong user demand, which provided feedback to microscoperesearchers and developers and a driving force to refine theproduct further.
Looking back at the history of optical microscopes in

84

Japan, whether it be the emergence of new methods ofmicroscopy or the adoption of infinity-corrected opticalsystems, it has all been to keep in step with inventions or
technological innovations overseas, especially Germany. It
has been a history of playing catchup, of working out how todevelop and market products with better function,
performance and cost performance than the preceding
German counterparts as soon as possible. However, amidst
all this, developers, engineers and manufacturers have put
their original creative ideas together and devoted themselvesto producing good products. This is Japan’s strength, and has
been the driving force in attaining to a world-leading
position. By sheer persistence, Japan has been able toproduce world-first products and technologies, such as the CF
optical system by Nikon and the fully automated universal
microscope by Olympus. Japan has finally drawn level toGermany and can be expected to produce new, original andimportant technologies and products in the future. Whether
this happens or not only depends on how much is invested
into technological development. This strongly depends on the
magnanimity of forward-thinking senior managers.
As stated many times over, microscopes are an important
tool in understanding the microscopic world. The aspirationof developers, or, to use an old turn of phrase, the “romance”
of developing our own products to achieve the ideal ofcontributing to the world has been a major source of
motivation. When the author was in charge of microscopelens design, he came across a translation of Scheffel’s“Gläserne Wunder”, or “the wonder of glass”. Translated
during the Pacific War, the book told the story of microscope
development success by Zeiss, Abbe and Schott. The authorof the present report recalls being profoundly impacted by
Abbe talent as a physicist, his struggle to establish
microscope theory and design, his leadership and guidance ofyoung researchers and his competence as a business manager
after Zeiss’ death, establishing the Carl Zeiss Foundation andsetting in a ground-breaking social security system that
implemented eight-hour work days, paid leave, a pension
system and freedom of ideology and background. The author
resolved to aspire to becoming a developer like Abbe. The
idea of taking over microscope development, brought thus far
by the wisdom, passion and perseverance of one’s forebears,
including current superiors and seniors, and contributing to
the advancement of science and industry by developing a
global-performing product was indeed a “romantic” notion
and it came with a sense of self-fulfillment. The author
recalls with gratitude being given the opportunity to work on
microscope development, and how deeply moving it was torival the world-leading German microscopes in a fight to the
top through the development of new LB, IC and UIS opticalsystems. Of course, there were many others working on thisbesides the author, and the sentiment is surely shared by all
business-founding pioneers, superiors, seniors and juniors
alike, and indeed anyone who has worked alongside Japanese
microscope manufacturers. It is because of this vector of
positivity, formed by so many involved in microscope
development, that Japan has become a microscopesuperpower. Such is the emotional belief of the author.
Dr Yamanaka Shinya was awarded the Nobel Prize inPhysiology or Medicine in 2012 for his research on iPS cells.

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. MarchDr Yoshinori Ōsumi received the same award in 2016 for his
research on autophagy. Both were dependent on the optical
microscope. In 2014, the Nobel Prize in Chemistry wasawarded to Betzig (USA), Hell (Germany) and Moerner(USA) for their research on super resolution fluorescencemicroscopy. This indicates that the world is paying attention
to new theoretical research using optical microscopes andnew practical development of optical microscopes. It is an
ongoing challenge to develop optical microscopes that go
beyond previous limitations. The author would be delighted if
this report were to be of some use to those working withJapanese microscopes, so that Japanese optical microscopes
will continue to lead the world.

Olympus Corporation:

Abe Katsuyuki
Yamashita Hideto

Olympus Museum of Technology
and History:

Matsui Tadahiko

Nikon Corporation:

Nakamura Atsumi
Mizuno Jirō
Yonezawa Yasuo
Takeuchi AtsushiŌuchi YumikoCarl Zeiss Microscopy GmbH:
Tanaka Tōru
Leica Microsystems GmbH:Acknowledgements
The author expresses heartfelt thanks to the following
people for their contributions of guidance, advice, valuable
resources and information for the preparation of this survey
report, “Systematic Survey on Optical MicroscopeTechnology in Japan”.

Nitta Kō
Sakura Finetek Japan Co., Ltd.
Osaka University Hospital:
Hamano Microscope Co., Ltd.:

Nishimura Hiroyuki
Inoue Ryō
Hamano Ichirō

Optart Corporation, formerly Union Optical Co., Ltd.:
Seya Masaki
Ohara Inc.:

Hirose Kōji
Shishido Hiroshi
Onozawa Masahiro

Shimadzu Rika Corporation:

Umeda Atsushi

Uchida Yoko Co., Ltd.:

Maeda Kimihiko

Shimadzu Foundation Memorial
Hall:

Kawakatsu Misako

Japan Microscope Manufacturers’
Association:

Kobayashi Tetsuo

Schott Japan Corporation:

Inoguchi Kazuyuki

Tanaka Scientific Limited:

Shimodaira KatsuhikoŌfusa Mayu

Mitutoyo Corporation:
Public Relations Section, Sales Division

Systematic Survey on Optical Microscope Technology in Japan85

Appendix 1
1. List of JIS Related to Optical Microscopes
JIS code: year ofenactment/revision
B 7132: 1949 → 1998

Biological microscopes

B 7132-1: 2009

Microscopes - Imaging distances related to mechanical reference
planes - Part 1: Tube length 160 mm
Microscopes - Imaging distances related to mechanical reference
planes - Part 2: Infinity-corrected optical systems

B 7132-2: 2009abolished 2009 ⇒ MIS 1001: 2011
ISO 9345-1
ISO 9345-2

B 7133: 1951

Biological microscopes for dry objectives

abolished 1998 ⇒ JIS B 7132: 1998

B 7134: 1951

Small size biological microscopes

abolished 1999 ⇒ MIS 8801: 2008

B 7135: 1957

Single objective binocular microscopes

abolished 1986 ⇒ JIS B 7132: 1986

B 7136: 1965

Medium size biological microscopes

abolished 1999 ⇒ MIS 9503: 2008

B 7137: 1990

Stage micrometer for biological microscopeabolished 1999 ⇒ MIS 9001: 2008

B 7138: 1990

Net Stage micrometer for biological microscopeabolished 1999 ⇒ MIS 9002: 2008

B 7139: 1951 → 1997

Stereo microscopes

B 7139-1: 2008

Stereomicroscopes - Part 1: Minimum requirements forstereomicroscopes

abolished 2008 ⇒ reorganized into JIS
B 7139-1 to 4:2008

B 7139-2: 2008

Stereomicroscopes - Part 2: Testing of stereomicroscopes

ISO 15227

B 7139-3: 2008

Stereomicroscopes - Part 3: Marking of stereomicroscopes

ISO 11883

B 7139-4: 2008

Stereomicroscopes - Part 4: Information provided to the user

ISO 15362

B 7140: 1951

Microscope test specimens

abolished 1999 ⇒ MIS 8602: 2008

B 7141: 2012

Microscopes - Screw threads for objectives and related nosepieces

ISO 8038

B 7142: 1951

Microscopes-Screw threads for objectives

abolished 1994 ⇒ JIS B 7141: 1994

B 7143: 1951 → 1977

Engagement between microscope eyepiece and eyepiece sleeves

ISO 10937

B 7144: 1951

Microscope - Connection of condensers for transmitted light with
substage sleevesabolished 1999 ⇒ MIS 9501: 2008

B 7145: 1951

Microscopes - The fitting of stage accessories

abolished 1999 ⇒ MIS 9502: 2016

B 7146: 1951

Fit of clips

abolished 1995 ⇒ JIS B 7145: 1995

B 7147: 1967

Biological microscope objectives

abolished 1999 ⇒ MIS 9301: 2011

B 7148: 1967

Microscope eyepieces

abolished 1999 ⇒ MIS 9201: 2007

B 7149: 1951

Microscopes - Eyepiece reticles

abolished 1999 ⇒ MIS 9505: 2007

B 7150: 1967

Micrometer microscopes

abolished 1999

B 7151: 1967

Micrometer eyepieces

abolished 1999

B 7152: 1967

Biological microscope objectives and eyepieces - Methods ofmeasurement of performance
Designation of microscope objectives - Part 1: Flatness offield/Plan
Designation of microscope objectives - Part 2: Chromatic
correction
Designation of microscope objectives - Part 3: Spectral
transmittanceabolished 1999 ⇒ MIS 9101: 2016

B 7251: 2000

Reference system of polarized light microscopy

ISO 8576

B 7252: 2015

Marking of microscope objectives and eyepieces

ISO 8578

B 7254: 2007

Microscopes - Magnification

ISO 8039

B 7255: 2007

Microscopes - Interfacing connection type C

ISO 10935

B 7256: 2007

Microscopes - Information provided to the user

ISO 12853, 2017 revision expected

K 2400: 2015

Microscopes - Immersion liquids for light microscopy(Supplementary Issue)

ISO 8036

R 3702: 1957 → 1996

Cover glasses for microscopes

ISO 8255-1 & ISO 8255-2

R 3703: 1957 → 1996

Slide glasses for microscope

ISO 8037-1 & ISO 8037-2

T 4204:

Hemocytometer

abolished 2001

T 10936-1: 2014

Operation microscopes - Part 1: Requirements and test methods

ISO 10936-1

B 7158-1: 2010
B 7158-2: 2011
B 7158-3

86

As at Dec 20, 2016

Corresponding ISO,combined/abolished

Title

ISO 11884-1 & ISO 11884-2

ISO 19012-1
ISO 19012-2
ISO 19012-3, 2017 enactment expected

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. March2. List of ISO Standards Related to Optical Microscopes
Code: year ofenactment/revision

As at Dec 20, 2016
Corresponding
JIS

Title

ISO 8036: 2015

Immersion liquids for light microscopy

K 2400

ISO 8037-1: 1986

Slides – Part 1: Dimensions, optical properties and marking

ISO 8037-2: 1997

Slides – Part 2: Quality of material, standards of finish and mode of packaging

ISO 8038: 2013

Screw threads for objectives and related nosepieces

B 7141

ISO 8039: 2014

Values, tolerances and symbols for magnification

B 7254

ISO 8040: 2001

Dimension of tube slide and tube slot connections―

ISO 8255-1: 2011

Cover glasses – Part 1: Dimensional tolerances, thickness and optical properties

ISO 8255-2: 2013

Cover glasses – Part 2: Quality of material, standards of finish and mode of packaging

ISO 8576: 1996

Reference system of polarized light microscopy

B 7251

ISO 8578: 2012

Marking of objectives and eyepieces

B 7252

ISO 9344: 2016

Graticules for eyepieces(B 7149)

ISO 9345-1: 2012

Imaging distances related to mechanical reference planes – Part 1: Tube length 160 mm

B 7132-1

ISO 9345-2: 2014

Imaging distances related to mechanical reference planes – Part 2: Infinity- corrected opticalsystems

B 7132-2

ISO 10934-1: 2002

Vocabulary for microscopy – Part 1: Light microscopy―

ISO 10934-2: 2007

Vocabulary for microscopy – Part 2: Advanced techniques in light microscopy―

ISO 10935: 2009

Interfacing connection type C

B 7255

ISO 10936-1: 2000

Operation microscopes – Part 1: Requirements and test methods

T 10936-1

ISO 10937: 2000

Diameter of interchangeable eyepieces

B 7143

ISO 11882: 1997

Interfacing connections for 35 mm SLR photo camera (T – thread adaptation)

ISO 11883: 1997

Marking of stereomicroscopes

ISO 11884-1:2006

Minimum requirements for stereomicroscopes – Part 1: Stereomicroscopes for general use

ISO 11884-2:2007

Minimum requirements for stereomicroscopes – Part 2: High performance microscopes

ISO 12853: 2015

Information provided to the user

B 7256

ISO 15227: 2000

Testing of stereomicroscopes

B 7139-2

ISO 15362: 2014

Stereomicroscopes – Information provided to the user

B 7139-4

ISO 18221: 2016

Microscopes with digital imaging displays - Information provided to the user regarding
imaging performance

ISO 19012-1: 2013

Designation of microscope objectives – Part 1: Flatness of field/Plan

B 7158-1

ISO 19012-2: 2013

Designation of microscope objectives – Part 2: Chromatic correction

B 7158-2

ISO 19055: 2015

Minimum requirements for binocular tubes―

ISO 19056-1: 2015

Definition and measurement of illumination properties - Image brightness and uniformity inbright field microscopy―

R 3703

R 3702―B 7139-3
B 7139-1―

Systematic Survey on Optical Microscope Technology in Japan87

3. List of MIS (Microscope Industrial Standards of Japan Microscope Manufacturers’ Association)
Code: year ofenactment/revision88

As at Dec 20, 2016
Title

MIS 7801: 2016

Enactment methods for industrial standards of Japan Microscope
Manufacturers’ Association

MIS 7804: 2007

Test Specimens for total parcentricity of small biological microscopes

MIS 8602: 2008

Microscope test specimens

MIS 8801: 2008

Small size biological microscopes

MIS 9001: 2008

Stage micrometer for biological microscope

MIS 9002: 2008

Net Stage micrometer for biological microscope

MIS 9101: 2016

Biological microscope objectives and eyepieces - Methods ofmeasurement of performanceMIS 9201: 2007

Microscope eyepieces

MIS 9301: 2011

Biological microscope objectives

MIS 9501: 2008

Microscopes - Connection of condensers for transmitted light with
substage sleeves

MIS 9502: 2016

Microscopes - The fittings of stage accessories

MIS 9503: 2008

Medium size biological microscopes

MIS 9001: 2008

Microscopes - Eyepiece reticles

MIS 1001: 2011

Biological microscopes

Corresponding JIS――
JIS B 7140 (abolished Oct
1999)
JIS B 7134 (abolished Mar
1999)
JIS B 7137 (abolished Oct
1999)
JIS B 7138 (abolished Oct
1999)
JIS B 7152 (abolished Oct
1999)
JIS B 7148 (abolished Oct
1999)
JIS B 7147 (abolished Oct
1999)
JIS B 7144 (abolished Oct
1999)
JIS B 7145 (abolished Oct
1999)
JIS B 7136 (abolished Mar
1999)
JIS B 7149 (abolished Oct
1999)
JIS B 7132 (abolished Oct
2009)

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. MarchAppendix 2
Establishments of Japanese Microscope Manufacturers (Members of JMMA and others)
Year
1875
1892
1906
1910
1914
″
1917
1919
1921
1927
1930

Comment
Founder Shimadzu Genzō commences production of scientific instruments(Kiyamachi, Kyoto)
Tanaka Mokujirō establishes Tanaka Merchants, importing medical instruments andchemicals (Nihonbashi, Tokyo)
Sugita Tōtarō establishes Sugita Merchants (Nihonbashi)
Uchida Kotarō establishes Suitaigō as a business for the South Manchurian Railway(Dalian)
Suzuki Tamotsu opens business Suzuki Tamotsu Merchants, importing opticalproducts (Yokohama)Matsumoto Fukumatsu establishes M & Katera Optical Works (Nihonbashihoncho)
Tokyo Keiki, Iwaki Glass and Fuji Lens Factory merge to form Nippon Kogaku K.K.
(Japan Optical Industries Company)
Yamashita Takeshi establishes Takachiho Works (Hatagaya, Shibuya)Katō Kakitsu and Shintō Shinkichi establish Kalnew Optical Industries (Yotsuya,
Shinjuku)
Suzuki Taiichi goes independent from Takachiho Works and establishes Toyo Optical
Company (Eliza)
Spectacles dealer Katō Rokujirō Merchants established (Takecho, Taito)

1960

Tokyo Optical established from the surveying instruments division of K. Hattori
Seikosha
Nishino Kunisaburō and others go independent from Takachiho Works and establish
Yashima Optical Co., Ltd.
Ima Koshichi establishes Ima Optical Manufacturing Company (Ima Precision
Instruments established the same year, Minamidai, Nakano)
Yamashita Takeshi establishes Nisshin Optical and Precision Instruments (sumpmicroscope)Ishii Harukichi establishes Kyowa Optical and Precision Instruments Works (Honan,
Suginami)
Suzuki Seitarō establishes Suzuki Works (Yayoicho, Nakano)Anno Kuniji establishes Nikken Nihon Microscope Works (Minamiaoyama, Minato)
Hiruma Teruji establishes Besta Optical Inc. (Minamidai, Nakano)Yashima Denki optical division established independently as Union Optical (founding
president: Yanagawa Satoru)
Ishii Hisayoshi and others establish lens design and manufacturing company
Sankeisha Co., Ltd. (Kamiuma, Setagaya)
Shimoyama Kazuyoshi establishes Krea Seiko Co., Ltd. (Hatsudai, Shibuya)
Konno Iseo establishes Shin Nihon Tsusho Co., Ltd. (Yotsuya, Shinjuku)
Hotta Fushio establishes Chuo Precision Industrial Co., Ltd. (Kanda Ogawamachi,
Chiyoda)Kitagawa Kiyosuke establishes Asahi Optical Works (Koenji, Nakano)
Minato Optical Industry Co., Ltd. established through funding from the city of Iida,
NaganoUchiyama Yasushi establishes Tokyo ITV Laboratory (later NJS Corporation)

1963

Yomoda Kazuo establishes NSK Ltd. (Aoyama, Minato)

1932
1935
″
1939
1940
1947
″
1948
″
″
1950
1954
1955
1956
1959

″

Shimodaira Makoto establishes Shibuya Optical Works (Hatsudai, Shibuya)

1975
1978
1985
1987
2011

Satō Zensuke establishes Meiji Labax Co., Ltd. (Higashiikebukuro, Toshima)
Kajiro Michio establishes Hirox Co., Ltd. (Akasaka, Minato)
Yamamoto Masao establishes Scalar Corporation (Wakaba, Shinkjuku)
Fujiyama Kazuo establishes Optart Corporation (Kōtōbashi, Sumida)
Yoshimine Takashi establishes Micronet Corporation (Kawaguchi, Saitama)

Now Shimadzu Corporation
Now Tanaka Scientific Ltd.
Now Sugitoh Co., Ltd.
Now Uchida Yoko Co., Ltd.
Now Tohkai Sangyo Co.,Ltd.
Now Sakura Finetek Japan
Co., Ltd.
Now Nikon Corporation
Now Olympus Corporation
Now Shimadzu Device
Corporation
Ceased operation in 2002
Now Carton OpticalIndustries Ltd.
Now Topcon Corporation

Now Ima Optical
Manufacturing Co., Ltd.
Ceased operation in 1950
Now Kyowa Optical Co.,Ltd.
Now Seiwa Optical Co., Ltd.

Company went bankrupt in2010

Now Lasertec Corporation
Now Nissho Optical Co.,Ltd.
Now Shibuya Optical Co.,Ltd.
Now Meiji Techno Co., Ltd.

Systematic Survey on Optical Microscope Technology in Japan89

Flow Chart of Japanese Optical Microscope Development

Appendix 3[Notes]1) indicates Japanese product name2) indicates a product system
3)

indicates correlation between optical system and product4) ()Abbreviated company names in parentheses are as follows:
AO American Optical, BL Bausch & Lomb, L Leica (Leitz), O
Olympus (Takachiho), M Mitutoyo, N Nikon (Nippon Kogaku),
R Reichert, S Kalnew (Shimadzu), T Tiyoda (M & Katera), U
Union Optical, Z Zeiss
5)The following abbreviations are used for country names:
IT Italy, UK United Kingdom, AT Austria, DE Germany, FR
France, PL Poland, US United States, NL Netherlands[Fluorescence Microscope(transmitted light)]

1911 Fluorescence microscope commercialized (R)1913 Lehmann develops fluorescence microscope (Z)1933 Haitinger (Austria) discovers fluorochromes[Phase Contrast Microscope] 1941 Phase contrast

microscope prototype

1903 Zsigmondy (Austria)
completed (Z)completes the ultramicroscope(Z)[Dark Field
Microscope]1781 Microscopes manufactured in Japan by Hattori
Eishaku, Aburaya Kichizaemon and Kobayashi Kiemon

1903 Zsigmondy (Austria) completes
the ultramicroscope (Z)Major microscope manufacturers

Campani (IT)Marshall (UK)
Ross (UK)
Culpeper (UK)Smith & Beck (UK)
Martin (UK)
Powell & Lealand (UK)
Ross (UK)
Watson (UK)
Adams and son (UK)
Nachet (FR)[Upright Biological Microscope]

Stereomicroscope

1893 Köhler illumination method
1938 Superphot

Specimen staining developed

1931 Fuji

1920 Asahi

1925 Joico
1914 M & Katera[Upright Biological Microscope]

1907 Tanaka microscope

1924 Kalnew (S)1934 Apochromat completed (O)Abbe (DE, Z)

1665 Hooke (UK)publishes Micrographia

1870 Objective lens design method
1872 Imaging theory[Compound
1758 Dollond (UK) invents
Microscope]1877 Homogenous immersion
High magnification achromat
Single lens achromatic lenses
1886 Apochromat completed
Invention of
the[Objective Lenses]
1830 Lister (UK)1837 Amici (IT)1938 Bögehold (DE, Z) develops
Plan objective lensmicroscope

1590 Janssen (NL)

[Reflected Light Microscope (Metallurgical): Upright]
1722 Réamur (FR) makes microscopeobservations of steel surface

1856 Sorby (UK) produces areflected light microscope[Inverted]
1834 Chevalier (FR)produces an inverted
microscope

Le Chatélier (FR)produces an inverted
microscope[Single microscope ⇒ dissection
microscope][Stereomicroscope (Convergent type)]

1670s Leeuwenhoek (NL)

1897 Stereomicroscopes manufactured (Z)using proposal by Greenough (US)1808 Malus (FR) discovers
polarized light1828 Nicol (UK) inventsa polarizing prism

90[Polarized Light Microscope]
1834 Talbot (UK) manufactures a polarized light microscope

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. March

1925 Ore microscope (O & S)

Year
[Super Resolution
Microscope][Multi Photon Excitation Laser
Scanning Microscope](see 8.1)

Molecular
biology(see 8.2)
Genomes(see 8.3)[Laser Scanning Microscope]

Cerebralnerves1950 Coons (US) establishes
fluorescence antibody technique
1967 Ploem (NL) publishes epi-fluorescence illumination method
Developed as a unit attached toeach microscope in the system

1976 Fluophot (N)[Modulation Contrast Microscope] 1975 Hoffman (US) publishes

Developed as a unit attached toeach microscope in the systemmodulation contrast method[Differential Interference
1965 Nomarski differential interference contrast microscope (Z)Contrast Microscope]1952 Nomarski (PL→FR) invents
differential interference method

1962 Yamamoto Tadaaki etal. publish theory on
differential interference
contrast

DNA

Developed as a unit attached toeach microscope in the system

1974 Transmitted light differential

1966 Biological S-Ke-T
interference contrast units for AH &and metallurgical S-R (N) BH (O)immune1949 Phase contrast device (T,O)

Developed as a unit attached toeach microscope in the system

1955 Phase contrast device (N)Developed as a unit attached toeach microscope in the system

1980 Diaphot TMD

1997 Eclipse TE300

2007 Eclipse Ti-E

1999 Eclipse TS100

1950 Standard (Z)1955 Photomicroscope (Z)1966 Photomax

1973 Axiomat (Z)1971 Vanox AH

1986 Axio series (Z)cellcultures1992 DM series (L)1983 New Vanox AH2Morphology

1957 DF model 1958 E model 1963 FH model

1967 Apophot
1948 O model 1949 K model 1956 S model 1961 S-Ke model

1958 Polyphot

1976 Biophot

1996
Eclipse E800,
E600, 400

1985 Microphot FX

1978 Optiphot X, Labophot Y

Histology

1959 R model

Pathology
1964 PlanApo 100×oil
1963-1967 Plan series
1963-1967 Plan series
1974 PlanApo series

Bacteriology

Major fields and viewing targets[Fluorescence Microscope (EpiIllumination)]

1984 MPlanApo series (M)Industry

1966 Photomax M

1986 Microphot FXM

1976 Metaphot

1978 Optiphot XP

1994 Optiphot 100S
2000 Eclipse L200A, 300D

1979 Optiphot-55

Material

1984 FS (M)1995 Epiphot TME300

1981 Epiphot TME

2008 Eclipse MA200

1990 Versamet 3 (U)1959 StereoZoom(BL)Quality
All products, functions andperformance progressively improving

Dissection[Stereomicroscope (Parallel type)]
1957Cloptic(AO)
1957 Inoue Shinya et al. announce a rectifier

1975 Rectifier (N)Developed as a unit attached to eachmicroscope in the system

Metallurgical/in
dustrial
Biological

Systematic Survey on Optical Microscope Technology in Japan91

Appendix 4Chronology of Optical Microscopes (focus on Japanese biological microscopes)
Year

Microscope Chronologyc. 1590

Janssen father & son (Netherlands) produce a compound microscope

1665

Hooke (UK) publishes “Micrographia” using a compound microscope

1667-1670s

Leeuwenhoek (Netherlands) discovers microbes using a single-lensmicroscope

1670s

Campani (Italy) produces a microscope

1690s

Marshall (UK) produces a microscope

1700s

Culpeper (UK) produces a microscope

1740s

Cuff (UK), Martin (UK), Adams (UK) and others produce
microscopes

1750s

Microscopes brought to Japan around this time

1765

Gotō Rishun introduces the microscope in “Oranda Banashi”

1781
1787
1813
1827

Amici (Italy) announces a water immersion objective lens

1828

Nicol (UK) invents a polarizing prism

1829

Lister (UK) publishes an achromatic objective lens for microscope

1833

Udagawa Yōan publishes “Shokubutsu Keigen”

1834

Talbot (UK) invents the polarized light microscope

1838

W. Watson & Son optical instrument business established (UK)1840

Spencer (USA) starts producing microscopes (later American Optical)

1846

Zeiss starts producing optical instruments (Jena, Germany)

1849
1850
1853

92

Hattori Eishaku and Kobayashi Kiemon manufacture wooden
microscopes
Morishima Chūryō describes a “micrascoben” and has an image of a
microscope in “Kōmō Zatsuwa”
Doi Toshitsura, feudal lord of Koga Domain, starts observing
snowflake crystals under microscope

Related Items
1608 Lipperhey (Netherlands) produces atelescope1609 Galileo (Italy) makes astronomical
observations by telescope1613 Saris (UK) presents a telescope to
Tokugawa Ieyasu

1758 Dollond (UK) designs an achromatic lens1822 Daguerre (France) invents thedaguerreotype photographic process

Kellner starts producing microscopes (Germany, Ernst Leitz from
1869)
Nachet (France) invents a binocular microscope using light splitting
prismsBausch & Lomb (USA) established, start optical instrument
production

1861

Pasteur (France) disproves the theory of spontaneous generation

1866

Royal Microscopical Society in London (RMS) established″

Abbe starts working at Zeiss, begins researching microscope theory

1873

Abbe publishes microscope imaging theory

1876

Reichert (Austria) microscope company established

1877

Abbe completes homogenous immersion method

1879

Hansen (Norway) discovers leprosy bacillus

1882

Koch (Germany) discovers mycobacterium tuberculosis, and thecholera bacterium the following year

1884

Abbe and Schott jointly establish an optical glass research laboratory

1886

Abbe completes the apochromatic objective lens

1890

Kitasato Shibasaburō and Behring (Germany) discover serum therapy(tetanus/diphtheria)

1893

Köhler (Germany) publishes a microscope illumination method

1894

Kitasato Shibasaburō and Yersin (France) discover the plague bacillus
respectively

1868 Meiji Restoration

1879 Edison successfully lights an incandescentbulb

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. MarchYear

Microscope Chronology

Related Items

1897

Greenough and Zeiss jointly complete a stereomicroscope″

Shiga Kiyoshi discovers dysentery bacillus

1903

Siedentopf (Zeiss) and Zsigmondy develop the ultramicroscope

1901 first Nobel Prize awards ceremony

1904

Köhler (Zeiss) develops the ultraviolet microscope

1904 Russo-Japanese War breaks out (to 1905)

1907

Tanaka Mokujirō (Tanaka Partnership) manufactures microscopes

1910

Katō Kakitsu and Shintō Shinkichi start prototyping microscopes,
joined by Terada Shintarō

1913

Lehmann (Zeiss) develops the fluorescence microscope

″
1914
″
1915
1917
1919

Noguchi Hideyo discovers syphilis spirochete in the brains of mental
patients
Tanaka microscope and M & Katera are prize-winning exhibits at theTokyo Taisho Exhibition
Matsumoto Fukumatsu of Iwashiya establishes M & Katera Optical
Works and begins selling
M & Katera V/III released
Nippon Kogaku K.K. (Japan Optical Industries Company) establishedby a merger of Tokyo Keiki, Iwasaki Glass and Fujii Lens Factory
Yamashita Takeshi establishes Takachiho Works (now Olympus),
releases the Asahi the following year

1920

Takachiho Works registers the “Olympus” trademark

1922

Olympus releases the Sakura student microscope (SA)

1924

Katō Kakitsu and Shintō Shinkichi establish Kalnew OpticalIndustries (now Shimadzu Device Corporation)

1925

Nippon Kogaku releases its first microscope, the Joico″

Olympus and Shimadzu jointly develop a ore microscope

1927

Suzuki Taiichi (former apprentice of Katō Kakitsu) establishes Toyo
Optical Company (Eliza microscope)″

Olympus releases the Showa oil-immersion microscope (GK)

1928
1929
1932
″

1923 Great Kanto Earthquake

Olympus Seika is awarded an Excellent Domestic Product Award at
the Enthronement Commemoration Exhibition and is gifted to His
Majesty the Emperor
Suzuki Junichi invents the SUMP method of microscope specimen
preparation
Zernike (Netherlands) announces the phase contrast microscope(awarded the Nobel Prize in 1953)
Ruska (Zeiss) announces the magnetic field electron microscope(awarded the Nobel Prize in 1986)

1933

Olympus releases the XA stereomicroscope

1934

Olympus completes the Apochromat objective lens″

M & Katera Optical Works changes its name to Tiyoda Optical

1935

Yashima Optical Company established1938″

Bögehold (Zeiss) designs a Plan objective lens with a flat image
surfaceOlympus completes the SuperPhoto universal photography
microscope

1941

Zeiss prototypes and announces a phase contrast microscope

1945

Optical instrument manufacturers start shifting to peacetime industries
at the end of the war″

Tiyoda Optical resumes microscope production

1946

Japan Optical and Precision Instrument Manufacturers’ Association
launched (microscope division launched)″

Olympus resumes production of the GK microscope at its plant in Ina

1948
1949

1914 First World War breaks out (to 1918)

1939 Second World War breaks out (to 1945)
1941 Pacific War breaks out (to 1945)

1946 World’s first electronic computer ENIAC
developed

Nippon Kogaku releases the O model, the first postwar microscope,
followed by the K model research microscope the following year
Tiyoda Optical and Olympus complete successive phase contrast
microscopes respectively

Systematic Survey on Optical Microscope Technology in Japan

93

Year
1950
1952
″

Nippon Kogaku releases the POH polarized light microscope

1953

Science Education Promotion Act established

1954
1955
1956
1957
″

Japan Optical Industry Association established (Japan Microscope
Manufacturers’ Association established)
Nomarski announces a transmitted light differential interference
contrast microscope

Related Items

1953 Watson and Crick propose a structure forDNA

Nippon Kogaku releases the S model high-grade system microscope
Olympus develops the DF high-grade microscope with Japan’s firstvertically moving stage
Inoue Shinya announces a rectifier with better light polarization
performance

1958

Olympus develops the E model biological research microscope

1959

Nippon Kogaku develops the S model Köhler illumination system″

Olympus releases the MK educational microscope

1960

Olympus releases the POM polarized light microscope″

Kalnew releases the SGL-600 educational microscope″

1960 Maiman succeeds with ruby laser
oscillation

Nippon Kogaku releases the E educational microscope
Nippon Kogaku and Olympus release the SMZ and SZ zoom-typestereomicroscopes
Yamamoto Tadaaki (Nippon Kogaku) and Françon jointly announce a
differential interference contrast microscope
Shimomura Osamu discovers green fluorescent protein (GFP)(awarded the Nobel Prize in 2008)
Olympus releases the EH & FH, Japan’s first high-grade microscopeswith built-in illumination“History of Japanese Microscopes” exhibit held at the National
Museum of Nature and Science

1961 Gagarin (USSR) becomes the first personin space

1964

Nippon Kogaku releases the MD inverted microscope

1964 Tokyo Olympics

1965

Tiyoda releases the FM200 transmitted light fluorescence microscope

1966

Olympus releases the Photomax universal photography microscope″

Nippon Kogaku releases the T (transmitted light) and R (reflected
light) differential interference systems″

Olympus releases the CK inverted culture microscope

1967

Leitz releases an epi-fluorescence system invented by Professor Ploem″

Nippon Kogaku releases the Apophot universal research microscope1969 Apollo 11 moon landing, first humans on
the moon

1970

Olympus releases the FLM transmitted light fluorescence microscope1970 Osaka World Expo

1971

Union Optical releases a Nomarski reflected light differential
interference system″

Olympus releases the AH (Vanox) high-end universal microscope

1973

Olympus releases the AH-RFL epi-fluorescence system

1974

Olympus releases the BH high-grade system microscope series

1975

Hoffman (USA) announces the modulation contrast method″

Tiyoda releases the MT-B high-grade system microscope, closes thefollowing year

1961
1962
″
1963
″

94

Microscope Chronology
Coons publishes an antibody antigen test method using fluorescencemicroscopy
Nomarski (France) announces a reflected light differential interference
contrast microscope″

Olympus completes the Plan Apochromat objective lens series″

Olympus releases a transmitted light Nomarski differential
interference device for the AH & BH″

Nippon Kogaku releases a high-performance polarized light rectifier

1972 Sapporo Winter Olympics

National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. March

Year
1976
1978

Microscope Chronology

Related Items

Nippon Kogaku releases the new CF optical system and the Biophot
high-end microscope
Nippon Kogaku releases the Optiphot and Labophot high-grade
system microscopes″

Olympus releases the new optical system LB series

1980

Olympus releases the BH2 high-grade system microscope series

1981

Nippon Kogaku releases the TMD (Diaphot) inverted microscope

1983

Olympus releases the AH2 (New Vanox) high-end universal
photography microscope

1984

Olympus releases the SZH high-end stereomicroscope

1985″

Nippon Kogaku releases the FX high-end universal photography
microscope, progresses to FXA in 1988
NJS Corporation (now Lasertec Corporation) releases a laser scanningmicroscope

1988

Nippon Kogaku K.K. changes its name to Nikon Corporation

1990

Olympus releases the LSM-GB biological laser scanning microscope

1989 Berlin Wall comes down, East and West
Germany united the following year

Olympus announces the new UIS optical system and releases the BX
high-grade system microscope
Nikon announces the new CFI optical system and releases the Eclipse
high-end system microscope series

1995 Windows 95 released, personal computers
grow in popularity″

Nikon releases the Fabre outdoor microscope1998 Nagano Winter Olympics

2002

Olympus releases the CKX inverted culture microscope2001 Synchronized terror attacks on the USA

2003

Olympus Optical Co., Ltd. changes its name to Olympus Corporation

2002 FIFA World Cup held in Japan & Korea″

Olympus releases the IX-DSU disk scanning confocal microscope

2006

Yamanaka Shinya publishes on induced pluripotent stem cells (iPS)(awarded the Nobel Prize in 2012)

2007

Nikon releases the Eclipse Ti inverted research microscope

2008

Sakura Finetek Japan releases the TTM-200 microtome

1993
1996

″ Hanshin-Awaji Earthquake

Olympus releases the FV10i confocal laser scanning microscope″

Nikon releases the A1 & A1+ laser scanning microscopes

2010

Olympus releases the BX63 & 53 high-grade system microscopes″

Nikon releases the A1R MP+ multi photon laser scanning microscope″

Nikon releases the N-SIM and N-STORM super resolution
microscopes

2012

Shimadzu Rika releases the BA210EINT digital microscope

2013

Nikon releases the SMZ2 research system stereomicroscope″

Olympus releases the FVMPE-RS multi photon excitation laser
scanning microscope

2014

Uchida Yoko releases the D-EL4N digital microscope″

Olympus announces the FV-OSR super resolution microscope

″
2015
2016

2010 Asteroid exploring spacecraft Hayabusa
returns to Earth2011 Great East Japan Earthquake

3 researchers from the USA and Germany who developed superresolution microscopy are awarded the Nobel Prize in Chemistry“A Century of Japanese Microscopes” exhibition held at the National
Museum of Nature and ScienceŌsumi Yoshinori awarded the Nobel Prize in Physiology or Medicine
for clarifying the mechanism of autophagy

Systematic Survey on Optical Microscope Technology in Japan95

96
National Museum of Nature and Science Survey Report of Systematization of Technology, Vol. 24 2017. MarchAppendix 5
Location Confirmation Findings for Historical Resources Related to Optical Microscope Manufacturing Technology
No.

1

2

Name
Japan’s oldest existingwooden microscope

Tanaka microscopeYearmanufactured

Manufacturer

Statusofresource

Location
Shimadzu Foundation Memorial
Hall, Kyoto

1781

Kobayashi
KiemonOn
display

1907

Tanaka Mokujirō(TanakaPartnership)In
storage, Inoue Ryo collection, Osaka
not open University, Kyoto
to thepublic3

M & Katera IV

1914

Terada Shintarō,
Katō Kakitsu,
Shintō Shinkichi,
Matsumoto
Fukumatsu

4

Apochromat objective lenses

1934

Takachiho Works(now Olympus)

On
display

5

Super Photo universal
microscope with photographic 1938
equipment (Universal)

Takachiho Works(now Olympus)

On
display

6

MD inverted microscope

1964

Nippon Kogaku(now Nikon)Ondisplay

7

High sensitivity polarized
light rectifier (Apophot
universal research
microscope)

1975

Nippon Kogaku(now Nikon)In
storage8

CF optical system and Biophot
biological research
1976
microscope

Nippon Kogaku(now Nikon)In
storage

9

New Vanox AHBS highquality photography
microscope

Olympus Optical(now Olympus)

On
display

1983

On
display

Reason for selection
This is a valuable resource that reveals the year of manufacture and the manner of use. The
authentication certificate on the box reads, “Made by Kobayashi Kiemon, 1781”. The
accompanying “microscope viewing instructions” also include descriptions of how to useinterchangeable objective lenses. (4.1, Fig. 4.1)
Japan’s earliest mass-produced microscope, marketed in 1907. Modeled on the Leitz microscopewith magnification from 25× to 600×. Won many awards at national expositions and similar.
(4.2, Fig. 4.5)

The M & Katera was an early mass-produced microscope that drove the Japanese microscopemarket before and after the war. The company later changed its name to Tiyoda Optical. The
developers and the technology laid the foundation for the Japanese microscope industry. (4.2,
Fig. 4.6). Registered as an Essential Historical Material for Science and Technology (No. 184) in2014.
Apochromat objective lenses correct chromatic aberration as much as possible and are made“Zuikodo” Olympus Museum of
from special lens material such as fluorite or alum, requiring advanced processing andTechnology and History,
assembling technology. For Japan to have achieved this before the war is a ground-breaking
Hachioji, Tokyo
achievement that indicates a high level of optical technology.
A universal microscope that combines all the prewar optical technology. Capable of transmitted“Zuikodo” Olympus Museum of and reflected light, bright field and dark field microscopy and with integrated projection,
photography and filming devices, this was an epoch-making product that could rival overseas
Technology and History,
products with every possible function for biological and metallurgical microscopes. (4.2, Fig.
Hachioji, Tokyo
4.10)
Japan’s first proper inverted biological microscope. Used for tissue cell research, it has a fixed
Nikon Museum, Shinagawa,stage and a focusing mechanism that raises and lowers the objective lens. The superiorTokyo
systematicity, which included a sideboard for filming equipment, has become standard in thehigh-grade inverted microscopes of today. (6.1, Fig. 6.2)
The rectifier was invented by Inoue Shinya et al. (USA) and uses a special optical system to100th Anniversary Project Room, dramatically increase polarized light characteristics, making it possible to view faintbirefringence and similar during biological development. This Apophot went on the market in
Nikon Kumagaya, Kumagaya,
1967 and was one of the highest quality microscopes of the day, with various types of viewing
Saitamapossible using transmitted and reflected light illumination at the same time. (5.4, Fig. 5.18)
This optical system marked a turning point for rapid improvement in Japanese microscope
objective lens performance. This was the first system in the world to have the eyepiece and100th Anniversary Project Room,objective lens correct aberration independently of each other, whereas the prevalent conventional
Nikon Kumagaya, Kumagaya,
systems used the objective lens and eyepiece together to correct lateral chromatic aberration. The
Saitamamicroscope itself had completely new functions and design. (7.4.2, Figs. 7.21 & 7.22, 4.6, Fig.
4.31)
This microscope has a fully automated photography device, including the world’s first autofocus“Zuikodo” Olympus Museum of for microscope. When the objective lens is changed electronically, the illumination system
automatically adjusts to the best setting. With one stroke, this ground-breaking microscopeTechnology and History,
system removed the labor intensity and provided the expertise for good quality
Hachioji, Tokyo
photomicrography. (4.6, Figs. 4.38-40)
Sakura Finetek Japan Co., Ltd.,
Chūō Ward, Tokyo