Endoscope with traced raster and elemental photodetectors

An endoscope is adapted for operation in association with an optical scanner which generates a beam of radiation tracing out a raster. The endoscope employs at least one optical channel comprising a bundle of coherent flexible optical fibers. Elemental photodetectors which may be mounted at either the distal end of the endoscope probe or the proximal end of the endoscope probe are employed for sensing reflected radiation and generating a video signal. The optical channel may also be employed for transmission of a high-energy therapy beam. The endoscope is capable of obtaining multispectral-multidimensional (e.g. stereo) images of the tissue under examination.

BACKGROUND OF THE INVENTION 
(1) Field of the Invention 
This invention relates generally to endoscopes, which are employed in 
medicine for imaging selective body regions and for facilitating the 
delivery of high-energy radiation for treatment purposes. More 
particularly, the present invention relates generally to endoscopes which 
employ fiber optic channels and which employ lasers or other high-energy 
radiation sources. 
(2) Prior Art and Pertinent Technology 
The new and improved endoscope and associated system of the present 
invention has particular applicability in medicine for use as a 
gastroscope, sigmoidoscope, uretheroscope, laryngoscope, and bronchoscope. 
The invention also has applicability in connection with industrial 
applications, such as, for example, remote focus flexible fiberscopes, 
micro-borescopes, and micro-fiberscopes. 
Conventional endoscopes typically employ incoherent bundles of optical 
fibers for transmitting light rays (typically white light) from a proximal 
end of a tubular instrument to the distal end. Typically, a pair of 
diametral channels are employed for illuminating an object to be imaged. A 
separate coherent flexible fiberoptic channel communicates from the distal 
end to the proximal end with an eyepiece, television camera, photographic 
camera or other imaging devices for providing an image. For relatively 
large diameter endoscopes, a separate flexible-fiber quartz channel may be 
employed for transmitting a high-powered beam of laser radiation to an 
object for therapeutic purposes. An auxiliary channel may traverse the 
tubular endoscope for receiving various instruments for severing and 
retrieving selected tissue. In addition, the endoscope may contain 
channels which provide for water and air communication with the distal end 
of the endoscope. 
Conventional endoscopes provide a reasonably high quality image especially 
enlarged-diameter endoscopes. Conventional endoscopes are quite versatile 
and perform a large variety of useful functions. The conventional 
endoscopic optic systems, however, do exhibit a number of deficiencies. 
When viewing objects under high resolution, the image may exhibit a mesh 
or chicken-wire effect wherein individual groupings of fibers are 
outlined. Conventional endoscopes also exhibit some degree of loss of 
contrast associated with scatter intrinsic to the illumination of the 
object, and also some loss of contrast due to veiling glare of the 
multiple optical components. The space requirements, e.g., the diameter of 
the endoscope, represents a design constraint which is significant when 
separate illumination and imaging channels are employed. Such a constraint 
may be quite critical for vascular endoscopes which image interior 
arteries having diameters on the order of two millimeters or less. Another 
constraint of the conventional endoscopic optic systems is that they do 
not provide an optical system which facilitates stereo or three 
dimensional imaging, or the opportunity to acquire 
multispectral-multidimensional images, simultaneously. 
The imaging channel of a conventional endoscope may be coupled to a 
television camera or the television camera may be employed in conjunction 
with an eyepiece by means of an optical beam splitter. The video signal 
output from the television camera is fed to a television monitor and/or a 
video recorder of a digital image acquisition system for processing, 
display and archival storage. The television camera may be a conventional 
television tube, a solid state video camera employing CCD chips, or other 
conventional forms. 
Sato U.S. Pat. No. 4,604,992 discloses a CCD video camera chip at the 
distal end of the endoscope. The disposition of the CCD chip obviates the 
use of the coherent fiber optic bundle for imaging, and thus, provides a 
system which produces an image not susceptible to the chicken-wire effect 
or to individually broken fibers which cause pixel dropout. The size of 
the CCD chip, however, limits the minimal diameter of the endoscope. The 
CCD video camera chip also allows for the passage of high energy laser 
radiation to be trained on the object for therapy while the object is 
concurrently viewed through the CCD imaging camera. 
Karaki et al U.S. Pat. No. 4,808,636 discloses a solid state type of 
imaging censor position at the proximal end of the endoscope. The analog 
video signal is converted to a digital signal. The digital signal is then 
processed to eliminate the chicken-wire or mesh effect and to account for 
the pixel dropout in the displayed image. Pixel dropout commonly results 
from broken fibers in the fiber optic bundle. The spacial resolution for 
the conventional endoscope is essentially determined by the diameter of 
the optical fibers and the magnification of the imaging optics. In 
general, the commonly employed fibers have diameters in the range of eight 
to ten microns for high-resolution endoscopes. 
Other references which are related to the general field of the invention 
are identified by patentee and patent number as follows: 
______________________________________ 
Mok U.S. Pat. No. 4,641,650 
Murakoshi and Yoshida 
U.S. Pat. No. 4,473,841 
Murakoshi and Ando 
U.S. Pat. No. 4,562,831 
Toida et al U S. Pat. No. 4,550,240 
Pinnow and Gentile 
U.S. Pat. No. 4,170,997 
Loeb U.S. Pat. No. 4,418,688 
Kanazawa U.S. Pat. No. 4,418,689 
Ogiu U.S. Pat. No. 4,419,987 
Epstein and Mahric 
U.S. Pat. No. 4,011,403 
Barath and Case U.S. Pat. No. 4,589,404 
Kato et al U.S. Pat. No. 4,706,118 
Takano U.S. Pat. No. 4,545,882 
Sheldon U.S. Pat. No. 3,499,107 
Sheldon U.S. Pat. No. 3,021,834 
Sheldon U.S. Pat. No. 2,922,844 
______________________________________ 
SUMMARY OF THE INVENTION 
Briefly stated, the invention in a preferred form, is a new and improved 
endoscope which incorporates a modified optical system for the endoscope, 
an optical scanner and an elemental detector-video system. The optical 
system is designed in one embodiment to employ a single coherent 
fiber-optic channel which can be used for both illumination and imaging. 
The endoscopic optical system, in conjunction with the optical scanner, 
permits acquiring images with improved contrast, improved spacial 
resolution, improved speed of response, the delivery of an independent 
beam of radiation directed precisely to a selected location of the object, 
multiple projection and multispectral imaging. 
An endoscope in one embodiment comprises a bundle of coherent flexible 
optical fibers which form an optical channel. An elemental photodetector 
generates an electrical signal having an instantaneous value which is 
proportional to the quantity of light which impinges on the photodetector. 
The endoscope is adapted for operation in association with an optical 
scanner which generates a beam of radiation tracing out a raster. The 
raster from the scanner traverses a beam splitter and is projected on the 
proximal end of the optical channel. The raster light traverses the 
optical channel and is projected through the distal end of the optical 
channel for illuminating the surface of an object to be examined. 
Radiation reflected from the surface traverses back through the optical 
channel and is directed by the beam splitter to the photodetector. A 
high-energy therapy beam may also be projected on the proximal end of the 
optical channel for traversal through the channel. The photodetector may 
be selectively responsive to a pre-established narrow band of the electro 
magnetic spectrum. 
In another embodiment, the endoscope comprises a bundle of coherent 
flexible optical fibers forming a first optical channel which extends the 
length of a flexible tubular probe. At least one incoherent flexible 
optical channel is received in the probe and diametrally spaced from the 
first optical channel for transmitting reflected optical radiation. 
Elemental photodetectors optically communicate with the incoherent optical 
channels and generate electrical signals having instantaneous values 
proportional to the quantity of light which impinges the photodetectors. 
Two incoherent optical channels may be provided and a photodetector 
associated with each incoherent optical channel forms a stereo pair of 
photodetectors to generate signals indicative of a stereo image of the 
surface of the object being examined. 
In another embodiment, the endoscope has one coherent flexible fiber 
optical channel and at least one elemental photodetector is mounted at the 
distal end of the probe for sensing reflected radiation from the object 
under examination. The optical fibers of the optical channel may have the 
general shape of an elongated truncated cone wherein the diameter of the 
fibers at the proximal end of the cone is significantly greater than the 
diameter of the fibers at the distal end of the cone. 
The proximal end surface of an optical channel may be defined by a 
substantially rigid connected bundle of fibers having a generally circular 
shape and the distal end surface of the optical channel may be defined by 
a rigid substantially connected bundle of fibers having a generally 
circular shape. The raster which is projected on the proximal end of the 
optical channel has a boundary which defines a central fiber region and an 
outer fiber region of the optical bundle. Photodetectors can be mounted 
for optical communication with optical fibers in the outer fiber region. 
Radiation reflected from the surface of the object being examined is 
transmitted through optical fibers of the outer fiber region, thereby 
permitting illumination and signal read out in a concentric manner. 
An object of the invention is to provide a new and improved endoscope 
combined with a video laser scanner system therefor which does not require 
the need for a separate illumination channel. 
Another object of the invention is to provide a new and improved endoscope 
which facilitates the use of stereo pairs and three-dimensional imaging of 
the surface to be illuminated. 
A further object of the invention is to provide a new and improved 
endoscope having a compact and efficient form which is adapted for use 
with high-energy laser radiation. 
A further object of the invention is to provide a new and improved 
endoscope and associated optical scanner system which is capable of 
imaging with one light or laser source while one or more other sources are 
employed simultaneously for therapy or other diagnostic purposes. 
A further object of the invention is to provide multispectral with or 
without multidimensional imaging. 
Other objects and advantages of the invention will become apparent from the 
drawings and the specification.

DETAILED DESCRIPTION OF THE INVENTION 
With reference to the drawings wherein like numerals represent like 
elements throughout the figures, an endoscope in accordance with the 
present invention is generally designated by the numeral 10 in FIG. 1. A 
video optical scanner camera (schematically illustrated) designated 
generally by the numeral 12 is optically coupled to the endoscope. Scanner 
camera 12 contains a laser on a white light source. The endoscope 10 is 
especially adapted for use in conjunction with a video optical scanner 
camera which traces out a raster of illuminating light. The endoscope 10 
has means for extracting a video signal 14 and an elongated flexible 
tubular probe 16 which is insertable into the body of a patient for 
examination and therapy purposes. The resulting endoscopic system, as will 
be hereinafter described, generates high speed, essentially lag-free 
images having a high resolution and wide dynamic range. The endoscopic 
system exhibits reduced scatter and reduced veiling glare and is adapted 
for spectral dependent tomography and multidimensional imaging including 
simple stereo projections. The endoscope probe 16 may be embodied in a 
relatively compact configuration which is dimensionally compatible with 
conventional, smaller diameter endoscopes. Probe 16 carries the coherent 
fiber optic channel 17. Another channel 19 of the probe might constitute a 
flexible tube through which a medical instrument, such as a biopsy tool 
can be passed. 
With additional reference to FIG. 3, the video optical scanner camera 12 
may be any of a number of conventional types. In preferred form, the 
camera 12 functions by projecting an optical raster of light onto the 
surface of an object. The camera senses the reflected radiation with an 
elemental photodetector to generate a video signal. Preferred cameras 
employ lasers 18 as a source of radiation although other non-laser sources 
can also be employed in connection with the invention. An associated 
raster generator 20 is optically coupled to laser 18 for generating an 
illuminating raster. As described herein, the invention is described in 
terms of a laser source of illumination for the object to be examined and 
imaged. The advantages of a laser source include a wide selection of laser 
lines, high optical efficiency, high energy generation for certain 
diagnostic and therapeutic procedures, well established relationships 
between the absorption of monochromatic lines and the identification of 
selected tissue and bones, and favorable reflection characteristics of 
selected lines for optimum contrast in obtaining an image. 
The video laser camera (VLC) 12 preferably comprises a high resolution, 
wide dynamic-range digital video imager 22 providing optimal contrast. The 
VLC 12 also preferably includes lasers 24 and an associated laser beam 
control 26 capable of simultaneously delivering localized high-power laser 
radiation for therapy. The VLC 12 preferably avoids the loss of contrast 
from scattered radiation that exists when an object is illuminated with 
white light over its full surface during an exposure as characteristic of 
conventional photography or television. The VLC 12 illuminates an object 
locally as the laser scans through a raster with monochromatic radiation. 
Each raster pixel is recorded in succession. Consequently, the recorded 
pixel is not subject to the loss of contrast inherent in conventional 
video imaging which loss is principally due to radiation scattered from 
other pixels. 
One suitable VLC 12 is a digital laser scanning fundus camera such as 
disclosed by A. Plesch et al, in an article entitled "Digital Laser 
Scanning Fundus Camera", Journal of Applied Optics, Apr. 15, 1987, Volume 
26, No. 8. The latter VLC employs an air-cooled Ar-ion laser. The laser 
generates a beam passing through two microscopic objectives to shape the 
beam and to define a shutter. The raster generator comprises a polygon 
mirror scanner and a linear galvanometer scanner. The illuminating beam is 
horizontally deflected by an eighteen-face polygon mirror scanner rotating 
at approximately 52,100 rpm. The exit plane of the polygon scanner is 
projected on a scanning plane by a confocal arrangement of two camera lens 
systems and a General Scanning linear galvanometer. The scanner deflects 
the illuminating beam vertically with a repetition rate of 50 hertz on a 
fly-back time of 2 ms. A second symmetrical arrangement of two camera 
objective lenses projects the laser beam via a semi-transparent mirror of 
low reflectivity onto the surface of the object to be examined, e.g., the 
retina of the human eye. 
Another suitable VLC 12 is an optical system such a disclosed by Johan S. 
Ploem in an article entitled, "Laser Scanning Florescence Microscopy", 
Journal of Applied Optics, Aug. 15, 1987, Volume 26, No. 16. The disclosed 
laser scanning system employs a laser beam which is expanded with a 
telescope to a size suitable for microscope objective lenses. The laser 
beam is displaced along two axes by an X-Y scanner unit consisting of two 
orthogonal galvanometer scanners. A pair of mirrors are interposed in the 
optical path. The beam is focused by a diffraction-limited spot on the 
object. Illuminated light is collected by the microscope condenser and 
directed to a photomultiplier tube. For florescence and reflectance 
microscopy applications, a light path retraces the entire illumination 
beam path in reverse, including the scanning mirrors, until the reflected 
beam is reflected by a beam splitter onto a photomultiplier tube. The 
disclosed confocal laser scanning microscopy provides for the imagery of 
multiple focal layers of the specimen and a three dimensional image 
reconstruction. Combinations of the images are stored in a computer memory 
for comparing phase contrast and florescence images of the same area of 
the specimen to enable multi-parameter analysis of various cells. 
Another suitable VLC 12 may be similar to the confocal microscope disclosed 
by W. B. Amos et al, in an article entitled, "Use of Confocal Imaging in 
the Study of Biological Structures", Journal of Applied Optics, Aug. 15, 
1987, Volume 26, No. 16. Light passes from a laser into a reflector. The 
reflector is a chromatic reflector for florescence microscopy or a 
half-silvered mirror for reflection imaging. The optical scanning system 
directs a parallel beam of light into the eyepiece of a conventional 
microscope. The beam is focused to a diffraction-limited spot in the 
specimen. Light reflected or emitted by the specimen returns along the 
original illumination path and is separated from the incident light at the 
reflector. 
A schematic block diagram of the principal components of a generalized VLC 
12 and the endoscope 10 which comprise the overall endoscopic/camera 
system is illustrated in FIG. 3. The endoscope is bi-directionally 
optically coupled to the VLC by an optical coupler 28 which may comprise 
any of a number of optical components. The video signal from the endoscope 
returns via the optical coupler 28 and is applied to a photomultiplier 30 
for transmission to the digital image acquisition and processing system 
22. The acquisition and processing system 22 may be integrated into camera 
12 or may be a separate unit. The video output signal from the camera may 
be transmitted to a work station 32. The work station 32 typically may be 
a console with interactive displays. The received video signals can be 
manipulated and studied by the diagnostician at the work station 32. The 
signals from the camera may also be cast into data form and transmitted to 
and from an archival storage 34. 
It should be clear that the video signal from the photomultiplier can be 
fed to an analog display system for direct viewing when the image 
acquisition is in real time. 
As will be further described hereinafter, the VLC and the endoscope 
cooperate to provide a system wherein, in addition to an imaging beam, a 
separate therapeutic laser beam generated by laser 24 of the camera is 
transmitted through the endoscope. The therapeutic beam is projected upon 
a selected location on the surface of the object or tissue under 
examination and the tissue is concurrently continuously monitored through 
the imaging optics system of the camera. The therapy beam can be precisely 
controlled by beam positional control 26 so that any localized region of 
the object being visually examined may be effectively treated without 
requiring repositioning of the probe end of the endoscope. In preferred 
form, the therapeutic laser 24 and the control 26 are integrated into the 
VLC 12. The VLC 12 can be configured to include as many lasers as required 
to provide a requisite monochromatic wavelength and power for illumination 
as well as therapy. The VLC can be employed for florescence imaging, i.e., 
with procedures where the incident radiation beam is in one wavelength and 
the imaging is accomplished with florescence radiation. The laser 
radiation, in some cases, can be employed when sufficient numbers of 
monochromatic lines are available in a manner similar to the illumination 
from a monochrometer with the system operating as a powerful scanning 
spectrophotometer. The VLC 12 also provides a high spacial resolution and 
a wide dynamic range, thereby permitting correlation between spacial 
features and spectral signatures. 
With reference to FIG. 2, one embodiment of an endoscope 10 comprises an 
elongated flexible tubular probe 50. Probe 50 is formed of flexible 
plastic, rubber or other conventional materials. A flexible coherent fiber 
optics bundle 51 comprising a multiplicity of optical fibers 52 traverses 
the length of the probe from the proximal end 54 to the distal probe end 
56. In the region adjacent to the proximal and distal ends, the coherent 
fiber bundle 51 is essentially rigid. The fibers 52 at the bundle ends are 
fused into the shape of a solid small cylindrical segment so that the 
individual fibers 52 of the bundle maintain their spacial relationship or 
coherency. 
The probe 50 is illustrated in relation to a body or tissue section 60 to 
be examined. The distal end 56 of the probe is positioned in close 
proximity to tissue section 60 by conventional means. The specific object 
(illustrated as a triangle) of the body section which is to be imaged by 
the endoscope is designated by the numeral 62. Monochromatic illumination 
light (L) from a laser raster scanner impinges a beam splitter 66 of a 
camera 12 for projecting an input raster 64 from the laser scanner onto 
the proximal end 54 of the probe 50. The light traverses the fiber optics 
bundle 51 of the probe and is projected through the distal end 56 so as to 
trace a raster 64' onto the surface of the object 62 to be examined. The 
raster light scans over the surface of the object in a serial fashion. 
Reflected light from the object 62 returns in the direction of the FIG. 2 
arrows through the fiber optics bundle and strikes the beam splitter 66 of 
camera 12. The reflected light is sensed by a photomultiplier 30 whose 
output is fed to a video amplifier 68. The amplifier 68 transmits an 
electrical video signal(s), which at a given instant of time, is 
proportional to the quantity of light reflected from the point on the 
surface of the object 62 to which the laser beam raster is projected. The 
electronic video signal can then be transmitted to an analog system for 
recording and display or to a digital imaging system for recording, 
processing and display. 
The latter described endoscope essentially employs a single fiber optics 
channel and does not require separate illumination and imaging channels. 
Moreover, by integrating the endoscope optical paths of the therapy laser 
beam with the imaging laser beam, the requirement of a separate 
therapeutic channel to carry high-powered laser radiation may also be 
eliminated. Consequently, the endoscope comprising probe 50 has particular 
applicability in connection with endoscopes for very small diameter 
applications such as required in the imaging of coronary arteries. Many of 
the conventional problems associated with high-powered light requirements 
are solved by lasers having a sufficient power to provide the selected 
monochromatic radiation to thereby operate in a far more efficient manner 
than conventional light sources. An additional advantage of the endoscope 
lies in the scatter reduction and the contrast improvement which is 
realized by recording the reflected radiation from successive localized 
pixels imaged as the beam serially progresses through a raster. The raster 
scanning process avoids the inherent problem of contrast loss through 
scatter that ordinarily prevails when illuminating the entire surface of 
an object and recording the image at the same time. In conventional 
endoscope optic systems, scattered radiation from one pixel is commonly 
detected in another imaged pixel to thereby reduce the intrinsic imaging 
signal. In addition, anti-reflection coatings can be applied to the 
optical fibers with a high degree of precision. The coatings minimize loss 
of contrast with a scanner employing monochromatic radiation compared to 
loss of contrast with a scanner employing a customary white light source. 
Consequently, the endoscope of FIG. 2 is particularly advantageous for 
applications wherein an image may be suitably observed by illumination of 
a single monochromatic laser line. 
With reference to FIG. 4, the endoscope probe 70 has a central flexible 
fiber optic bundle 72 for raster illumination of the object 62 of tissue 
to be examined. A pair of diametrically opposed light channels 74 and 76 
of optical fibers extend longitudinally parallel to bundle 72 to transmit 
the reflected radiation from the object 62 along an optical path extending 
from the distal probe end 78 to the proximal end 80 of the endoscope. 
Photodetectors 82 and 84 are positioned at the proximal ends of the light 
channels 74 and 76, respectively. The reflected radiation transmitted 
through the light channels impinges the photodetectors 82 and 84. The 
photodetectors 82 and 84 in turn generate electrical video signals S.sub.1 
and S.sub.2 for processing as previously described. 
The monochromatic light from the laser raster scanner 20 and laser therapy 
positioner 26 is applied at the proximal end 80 of the fiber optics bundle 
72. The endoscope of FIG. 4 does not employ a beam splitter. Consequently, 
reflections from the proximal input surface of the fiber optics bundle 72 
are minimized. Reflections are also encountered in connection with beam 
splitters. In addition, the problem of veiling glare associated with 
multiple optical components in an imaging chain may also be substantially 
reduced by the elimination of the beam splitter. Short time constant 
photo- detectors are preferably employed so that the time lag 
characteristic which conventionally prevails in conventional endoscopic 
optical systems using video tubes is avoided. 
Because two detector illumination channels 74 and 76 are employed with each 
illumination channel having its own photo-detectors 82 and 84, two images 
in the form of signals S.sub.1 and S.sub.2 can be acquired independently. 
The channels can thus be combined to form a stereo pair. Alternatively, 
the images acquired may be from two widely separated spectral regions, 
such as the UV and IR, if desired. 
With reference to FIG. 5, endoscope probe 90 has a central coherent fiber 
optics bundle 92 which extends longitudinally from the proximal end 91 to 
the distal end 93. The fiber optics bundle 92 functions as previously 
described to project a video raster 64, onto the object 62 to be examined. 
Elemental photodetectors 94 and 96 are mounted at the distal probe end 93 
of the endoscope for detecting incident reflected radiation from the 
object 62. Wires 98 extend the length of the endoscope for carrying the 
electrical bias and the signal current from the elemental photodetectors 
94 and 96. The electrical video signals S.sub.1 and S.sub.2 communicate 
via the electrical wires 98 with the circuitry for processing the video 
signal. 
It should be appreciated that endoscope probe 90 does not require separate 
optical detector and illumination channels since the elemental 
photodetectors 94 and 96 are located at the distal end 93 of the 
endoscope. As the illumination beam scans out a raster, the video signal 
is generated in a highly efficient manner since the photodetectors are 
positioned in an optimal location in the immediate vicinity of the object 
62 to be examined. The photodetectors 94 and 96 may be relatively small in 
dimensions. Thus, the diameter of the endoscope probe 90 may be relatively 
small. One or more stereo pairs of images may also be obtained. Several 
photodetectors may be positioned at the distal end of the probe. The 
photodetectors may be configured into shapes which are circular, square, 
rectangular, polygonal, or other shapes as desired. 
An endoscope comprising probe 90 avoids the loss of optical transmission 
through the illumination channels. Quartz fibers typically provide optical 
transmission throughout the spectrum range for a wide variety of 
applications between 3,000 Angstroms and 2 microns. The elemental 
photodetectors can be selected so as to operate in the spectral range from 
3,000 to 20,000 Angstroms. One or more small photodetectors can be 
selected and suitably positioned at the distal probe surface of the 
endoscope to specifically respond to whatever radiation is selected for 
the imaging and therapy, regardless of the wavelength of the reflected 
radiation. It should be appreciated that a given endoscope, as described, 
is suitable for UV imaging as well as for imaging at two microns. The 
endoscope probe 90 offers wide range of spectral response. For example, 
signal S.sub.1 may be responsive to reflected radiation imaging in one 
given spectral region and signal S.sub.2 may be responsive to reflected 
laser therapy radiation in another spectral region. Endoscope probe 90 is 
also adaptable for multi-spectral imaging for contrast enhancement for a 
given endoscope. 
Photodetectors 94 and 96 which are suitable for the described endoscope can 
be fabricated from materials such as crystalline silicon, amorphous 
silicon, cadmium sulfide and lead sulfide. For operation in the 
ultra-violet through the visible spectrum, into the near infra-red, the 
photodetectors as described provide extremely reliable performance at body 
or room temperatures. Combinations of infra-red transmitting fiber and 
cooled photo-detectors may also be employed for infra-red applications. 
Uncooled thermal detectors which offer less performance may be 
satisfactory for some infra-red applications. 
The laser camera system, as described, may function as an imaging scanner 
spectrophotometer by using one or more photo-detectors with their spectral 
responses matched to that required for the given spectrum encompassed in 
an application. The relative spectral reflectance for each pixel in an 
image can be measured for a given imaging radiation. By precise 
calibration, absolute reflectance values can be obtained. 
The laser therapy can be effectively accomplished with the described video 
laser camera systems and endoscopes. If a given laser line is best suited 
for a given therapy, the laser line can be transmitted through one or more 
of the fibers to the object requiring treatment. The number of selected 
fibers defines the composite therapy beam diameter. For example, if a 
lesion on the surface of the object is imaged by ten to twenty fibers, 
then the laser radiation for therapy could be channeled through the same 
fibers of bundle 92 to cover the designated lesion area. Simultaneous 
imaging may also be accomplished through the same fibers consistent with 
the raster scanner operation. The high-powered therapeutic radiation 
generated by laser 24 can be shuttled back and forth through the fiber 
optic bundles or even pulsed through one or more fibers to minimize the 
heating problems. Heating, in general, is ordinarily not a critical 
problem, since high-temperature glass fibers have been developed which 
operate at temperatures up to 800.degree. Fahrenheit. Quartz fibers have 
an even higher temperature operational limit. 
For the described endoscopic systems, there are two principal operational 
techniques wherein the high-energy therapy irradiation of an object can be 
accomplished simultaneously with viewing the reaction of the object to the 
irradiation treatment. In one technique, both the imaging beam and 
high-energy therapy beam pass through the scanning system. Such an 
approach requires that the high-energy therapy beam be pulsed in 
synchronization with the scanning raster so that the high-energy therapy 
beam is delivered in a precise manner. The first approach requires that 
the precise timing of the imaging pulses and therapeutic laser pulses be 
coordinated. 
In a second technique, the high-energy irradiation is transmitted by a 
second separate optical system. This second general approach does not 
require the pulsing of the therapeutic beam and synchronization of the 
scanning of the raster. However, the imaging channels might need to be 
filtered so that the high energy irradiation does not interfere with the 
imaging process. Consequently, photo-detectors employed in such a system 
could require sufficient filtering so that the photodetectors selectively 
respond only to radiation from the low-energy imaging beam. For endoscope 
probes 70 and 90, which employ multiple detectors, one or more of the 
photodetectors may be employed to sense (view) the imaging radiation while 
being opaque (blind) to the high-energy radiation. By the proper selection 
of the photodetector and the filter, detectors may be employed to monitor 
the level of reflected radiation with time as the high-energy therapy beam 
causes a change in the reflectance properties of the object or tissue on 
which the high-energy beam is focused. 
It should be noted that the use of multiple-elemental detectors, which are 
each capable of providing an independent image of the object from a 
different viewing angle, makes possible stereo imaging. Any such pair of 
the images (electrical signals) essentially can be electronically coupled 
to constitute a stereo pair. One or more elemental detectors positioned at 
different viewing angles relative to the object result in the images being 
multiply-generated to obtain the optimal stereo view of an object. In 
addition, spectral selective viewing of a structure below an object 
surface can be obtained since the images obtained from different laser 
wavelengths can in certain cases represent different depths of penetration 
below the surface of an object. Tomographic planes may thus be 
constructed. 
Contrast enhancement can also be obtained by multi-spectral imaging. The 
multi-spectral imaging is accomplished by means of employing 
photodetectors having different defined spectral responses. Processing of 
the electrical video signals may be accomplished by means of energy 
subtraction techniques such as are employed in digital radiology and 
red-near infra-red subtraction techniques employed in diaphranography of 
the breast. 
With reference to FIG. 6, one embodiment of a rigid coherent fiber optics 
bundle 100 for an endoscope as previously described comprises a proximal 
cylinder 102 consisting fused strands of substantially identical optical 
fibers 104. Likewise, a distal cylinder 106 comprising fused strands of 
the fibers is formed at the distal end of the endoscope. The diameters of 
the fibers of the proximal cylinder 102 are significantly larger than the 
associated corresponding optical fiber diameters of the distal cylinder. 
The optical fibers 104 may have a substantially constant taper from the 
proximal to distal ends. Thus, the individual fibers 104 may be described 
as elongated truncated cones. 
Monochromatic light from the laser raster scanner is applied at the input 
surface 108 of the proximal cylinder 102. The relatively large input 
surface 108 defined by the proximal end of the fibers 104 functions to 
provide large heat capacity, means for cooling and a better ability to 
withstand damage from intense laser radiation, at optics bundle 100. In 
conventional endoscopes, high-energy laser radiation frequently does often 
result in fiber damage, particularly at the proximal end of the endoscope 
fibers. Because the flexible optical fibers are selected to be highly 
transmissive, the fibers are not particularly subject to appreciable 
increases in temperature unless there are localized impurities. However, 
the proximal cylinder 102 is susceptible to damage in large part because 
of the high absorption in the cladding material which leads to excessively 
high temperature and damage from thermal shock. By constructing the fiber 
diameters at the input surface 108 to be much larger than the fiber 
diameters at the output surface 110, the potential for thermal shock can 
be diminished. Thus, all other relevant physical characteristics of bundle 
100 being equal, the energy density of a laser beam transmitted through 
fiber bundle 100 could be considerably increased and the heat capacity 
input considerably increased while decreasing the potential damage to the 
fiber optics bundle. For example, for a bundle 100 where the diameter of 
the input surface 108 to the output surface 110 is 10 to 1 a 10 micron 
flexible fiber optic bundle could have an effective input of 100 microns. 
For procedures which involve multi-spectral imaging, surface tomography, 
different spectral responses and different perspectives, multiple 
detectors may be required. Such detectors may be efficiently arranged and 
mounted at the proximal end or region of the fiber optics bundle as 
illustrated in FIG. 7. For the configuration illustrated in FIG. 7, 
boundary 120 (schematically illustrated) of the raster which is projected 
onto the proximal cylinder encompasses only a central portion of the 
entire cross-sectional extent of the fiber optics bundle. Accordingly, an 
outer ring 122 of fibers are available for coupling to the photodetectors 
124. Essentially, the central raster illumination transmission zone, 
defined by boundary 120, is encircled by a concentric ring 122 of fiber 
channels. The fibers in the ring 122 can be employed, either individually 
or collectively in groups, to transmit the reflected radiation from the 
tissue surface illuminated by the laser radiation near the distal end of 
the endoscope probe back to the photodetectors 124, which are located at 
the proximal end. 
In one example, the diameter of the input proximal end 108 of the fiber 
optic bundle 100 is four millimeters, and the diameter at the distal probe 
end 110 is one millimeter. The effective demagnification of the fiber 
optics bundle 100 is approximately four. An individual fiber at the 
proximal end having a diameter of 40 microns has a corresponding diameter 
at the distal end of 10 microns. If laser raster defined by a square 
boundary 120 having a diagonal dimension of two millimeters is centrally 
projected on the proximal surface 108, a one millimeter thick ring 122 of 
fibers remain to function as the optical channels for photodetection. Such 
a ring could accommodate twelve detectors 124 in side-by-side orientation 
having dimensions of approximately one-by-one millimeter. The specific 
shape and dimensions of the detectors 124 could be suitably varied in 
accordance with the requirements of a specific application. 
A laser raster scanner system as described can be employed in conjunction 
with multiple photodetectors to provide multi-spectral imaging. For 
example, an Nd:YAG laser which generates the typical line at 1.064 microns 
and a strong line at 1.318 microns can be coupled to different elemental 
photodetectors. Each of the elemental photodetectors is responsive to one 
of the laser lines so that the object under examination can be imaged 
simultaneously with both lines. For example, a laser system, such as 
described by R. A. Morgan, "Nd:YAG Laser For the Study and Application of 
Non-Linear Optical Chrystals", Optical Engineering, Volume 26, Pages 
1240-1244, 1987, when suitably coupled with non-linear optical crystals, 
can permit simultaneous generation of frequencies extending throughout the 
visible spectrum, including the three primary colors and into the near 
ultra-violet range. 
While preferred embodiments of the invention have been set forth for 
purposes of illustration, the foregoing description should not be deemed a 
limitation of the invention herein. Accordingly, various modifications, 
adaptations and alternatives may occur to one skilled in the art without 
departing from the spirit and the scope of the present invention.