Microscope including a fade-in element and related method of using a microscope

A microscope is disclosed for observing a magnified area. Fade-in means arranged in the path of the rays of the microscope reflect a thin focused beam of light into the path of the rays. The beam of light is deflected or modulated by deflecting means to supply an image that can be recognized by an observer. The image may be projected onto the object either directly or indirectly, for example through a diffusing screen.

BACKGROUND OF THE INVENTION
 The invention relates to a microscope having at least one beam path and an
 optical system along an optical axis, and having a fade-in element for
 reflecting in image information for an observer's eye. Microscopes in the
 sense of the invention are to be understood principally, but not
 exclusively, as devices which have a main objective, a tube and an
 eyepiece for looking into. In the widest understanding of the invention,
 therefore, all other optically magnifying devices are to be understood
 which are directed onto an object to be magnified and make visible to the
 observer's eye a magnified image of the object observed. Microscopes, in
 particular stereomicroscopes, for example surgical microscopes, in
 particular also video (stereo)microscopes which are connected to an
 electronic data processing unit and/or a display are comfortable for a
 user when the latter is not exclusively dependent on the image currently
 seen through the main objective of the microscope, but also obtains when
 looking into the tube of the microscope additional information which is
 generally superimposed on the currently seen image. This can be graphic
 characters, symbolic representations, marks, but also superimposed images
 of the same object which are obtained, for example, with the aid of image
 processing software from the currently seen object or by means of other
 visualizing measures (for example X-ray pictures, CT etc.) from the same
 object. Microscopes with fade-in possibilities or image superimposition
 possibilities are also used, inter alia, in technology, for example
 materials engineering, material analysis, silicon technology criminology,
 etc., but also, in particular, in medicine for diagnosis, serological
 examinations, during operations etc.
 Chiefly in the case of surgical microscopes and, in particular, during an
 operation, a quantity of information arises which can be of great
 importance to the surgeon. This is, for example, information on the
 patient or his state of health or patient parameters such as pulse, blood,
 pressure, oxygen content of the blood etc. These are in addition to the
 currently observed superimposing images, for example, information on
 specific parameters of the microscope, information on the position of the
 observed operation zone, as well as control data which, for example, the
 surgeon delivers at will via control elements such as computer mouse or
 foot switch to the data processing device or to control elements for the
 microscope, in order to control the latter as required, for example to
 focus it, etc.
 The use of the invention in the field of surgical microscopy will be taken
 up below by way of example. The invention is also applicable in other
 fields.
 Surgical microscopes are used by the operating surgeon for optical
 magnification of the operation zone. Operation technology is so far
 advanced in this connection that magnifications in the region of 50 fold
 and above are no rarity. It is important during an operation that the all
 important information is transmitted to the operating surgeon as quickly
 and unambiguously as possible, in order for him to be able to conclude the
 operation in as short a time as possible. Since the operating surgeon
 preferably removes his eyes as little as possible from the eyepiece of the
 surgical microscope, and, conversely, difficulties of comprehension can be
 expected with the spoken word, it is obvious for important information
 such as, for example, patient data, micoscope control data or positional
 data to be rendered visible in the tube.
 This is achieved according to known techniques by representing the relevant
 information on a display and reflecting the image of this display into the
 tube via a beam splitter. Because the user always wants a good light yield
 for the object observed, which can frequently be ensured by high
 illumination densities at the object, the problem of adequate optical
 density of the image reflected in or superimposed often arises in the case
 of reflecting in. In this case, tube displays (CRT) frequently provide no
 way out. The use of LCDs with strong background illuminations is; attended
 by disadvantages in the field of resolution and also in attempting to
 reproduce thin lines, also since the pixel width of the LCDs is relatively
 large, and therefore relatively wide minimum line thicknesses are
 prescribed. Moreover, LCD pixels form rasters which can produce problems
 with edge definition and resolution.
 If it is now desired, for example, to have edge improvements, image
 colorings, contrast improvements or other marks which are as thin as
 possible, and which have been prepared, for example, after prior recording
 by means of video technology and by means of electronic image processing,
 it can happen disadvantageously that the known possibilities produce
 unsatisfactory performance with regard to brightness and/or line
 thickness. Contouring would be desirable, but not: achievable optimally
 using the means of the prior art.
 A special field for the superimposition of images rises, for example, in
 the application of computer tomography (CT) or magnetic resonance imaging
 (MRI) in conjunction with stereomicroscopy. Data are obtained from CT and
 MRI in order to obtain a sectional image of the zone of interest from the
 patient which, in the final analysis after EDP, permits the representation
 on a computer monitor (stereo display screen) of a three-dimensional model
 which is faithful to reality. By using such three-dimensional images, the
 attending doctors are better able to localize the type and spread of the
 diseased area. However, it is frequently the case that both the image
 currently seen and the available three-dimensional representation of X-ray
 or CT image data are not clear enough for the relevant area to be
 identified during operation in a marked-off fashion with sufficient
 clarity from the remaining region.
 As already mentioned, contour reworking or contour representation suffice
 for this identification to be performed optimally, but these are to be as
 bright and thin as possible in order not to cover other details.
 Accomplishing this is one of the main objects on which the invention is
 based.
 SUMMARY OF THE INVENTION
 This object is achieved, for example, by utilizing the method and device
 describe herein.
 The problems described are eliminated by superimposing onto a first image,
 seen through the main objective (8) of a microscope, such as shown in FIG.
 1 at least one second image from a thin, focused light beam, in particular
 a laser beam which is deflected and/or modulated in a deflecting device
 and reflected into the beam path of the microscope via a fade-in element
 in such a way that it visibly represents the second image for an
 observer's eye. A thin light beam, in particular a laser beam, can be
 generated in a virtually arbitrarily thin and bright fashion.
 It is relatively easy for the components newly required for this in
 accordance with the invention to be integrated into a microscope. Fade-in
 elements, suitable light sources, in particular lasers, are known per se
 to the person skilled in the art. However, despite their favorable
 properties, they have evidently not been used so far for the effects being
 sought in the field of microscopy.
 It is not important here for the purpose of the invention whether the thin
 light beam or laser beam is projected by the optical system directly onto
 the retina or onto an interposed diffusing screen, or else directly in the
 other direction onto the object itself, in order to represent the
 corresponding marking there on the object surface.
 Within the scope of the invention, there are both variants in which, in the
 operating state, the light beam extends in the region of an intermediate
 image plane of the optical system in a fashion approximately parallel to
 the optical axis in the direction of the eyepiece, and variants in which a
 diffusing screen on which the light beam can be scattered is arranged in
 the intermediate image plane.
 For the purpose of the invention, a diffusing screen is in this case any
 optical element on which a thin light beam is scattered upon impingement
 in such a way that its point of contact can be seen from different points
 of view. Thus, this could also be an uncoated glass plate. However, it can
 also be, for example, a beam splitter to which a scattering coating is
 applied to a surface inside the optical system, or one surface of which is
 roughened.
 According to the invention, any desired pictorial information can be fed to
 the observer by means of a light beam and deflecting device. In accordance
 with a specific embodiment of the invention, the deflecting device and/or
 the light source is controlled by an image processing device for contour
 representation, which is coupled to an image recording device which is
 coupled to the optical system via a further fade-in element. This permits
 direct feedback between the image of the object which is seen and the
 image represented by means of the beam. This variant is advantageous by
 virtue of the brightness of a focused light beam. Despite a bright
 operating field of view, the area to be emphasized is seen by the
 operating surgeon in a clearly highlighted fashion. This is so, of course,
 even in the case of variants in which not only the image seen optically is
 the basis for the image representation of the beam, but also the
 diagnostic data, acting as though at the same object position, from a
 diagnostic data device (for example a CT, MRI, PE device or the like).
 In the latter variants, it is preferred to provide in each case at least
 one beam path per observer's eye (stereomicroscope), it being the case
 that in each beam path in each case one left-hand and right-hand item of
 partial image information, which are offset in terms of perspective in
 relation to the respective other one can be reflected in from one, or in
 each case one deflecting device via a fade-in element in each case, the
 deflecting device(s) being controlled by an image recognition and/or image
 processing device. An image recognition device is to be understood as a
 system which is able to recognize the identity of the objects observed
 through different observation units, and in this way enables image data to
 be superimposed in the correct position.
 The preferred method is yielded in this connection when the deflecting
 device is controlled by image information obtained from the object
 observed through the microscope, so that, for example, contours of object
 details are retraced, or object details are represented by means of grid
 lines or the like at the actual site of the object detail in the visual
 field area, of course, such grid lines have the ideal effect principally
 in the case of stereomicroscopes when they are used to retrace a specific
 object detail (for example a tumor) in three dimens ions or in plastic
 terms.
 In accordance with a development of the invention, a continuously
 controllable light valve is placed in front of the light source, so that a
 user can regulate the brightness of the image faded in by means of the
 beam. When conventional lamps are used, it is also possible, of course,
 for their brightness to be regulated via the power supply. In the case of
 lasers, in particular, however, the abovementioned variant is to be
 recommended. Operating convenience is enhanced if the light color of the
 light source or of the laser can also be adjusted, something which is
 possible by measures known to experts in light sources or lasers.
 Further advantages follow in accordance with further special embodiments of
 the invention in which the image observed (background image) exerts a
 reaction on the superimposed image. According to the invention, the
 procedure here is based on two points of view: relative brightness of
 individual pixels with respect to one another, and total brightness of the
 image, limited by possible adaptation behavior.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
 The figures are described together and inclusively. The same reference
 symbols denote identical components. The same reference symbols with
 different indices denote similar or functionally similar components. The
 invention is not restricted to the exemplary embodiments represented.
 Further arbitrary variants can be represented in combination.
 One the principles of the invention is illustrated in FIG. 1:
 A beam path 1 having a magnifying optical system 33, of which only two
 lenses, specifically a main objective 8 and an eyepiece 18, are
 represented symbolically, has an obliquely positioned beam splitter 32a by
 means of which both the image information is directed to the eyepiece 18
 through the main objective 8, and image information reflected in from the
 side is directed to the eyepiece 18. The beam splitter can be a
 semireflecting mirror or the like. It can also possibly be constructed in
 a miniaturized fashion as a small mirror which is bonded on a glass plate
 perpendicular to the optical axis 7, such a latter design always
 functioning with divergence of the beams 101, which, if appropriate,
 requires additional computational outlay for the beam deflection.
 According to the invention, the image information reflected in from the
 side comprises an image of a thin, focused light beam 101, in particular a
 laser beam, which follows the lines to be represented pictorially in a
 repeated fashion at the required speed, thus rendering a coherent image,
 for example lines, numbers, letters, symbols, areas etc., visible to an
 observer. These are scattered on diffusing screen 108a and are
 distinguished there by a good brightness (virtually unlimited, depending
 on the laser power) and thus by a distinct contrast with respect to the
 image seen through the main objective 8. The image of the scattered laser
 beam is projected onto an intermediate image plane 103 of the tube by
 means of a lens 31 via the beam-splitting mirror 32a. The beam is
 deflected or moved by a deflecting device 102, known per se which has
 mirrors or the like which can move under control, and in this way can
 deflect a beam 101 irradiated into it. It goes without saying that a
 plurality of beams with, if appropriate, a plurality of deflecting devices
 as well, could also be provided simultaneously. It is also conceivable, if
 required, for a plurality of laser beams to be run together on the
 diffusing surface, in order to increase the energy density and thus the
 brightness. The movement of the beam 101 is represented symbolically by a
 dashed arrow of rotation. The beam 101 is obtained from a light source 64,
 in particular from a laser, which could, of course, also be integrated
 into the deflecting device.
 Also represented in the exemplary embodiment shown is a light valve 107
 which makes the brightness of the beam 101 controllable. The deflecting
 device 102, light valve 107 and light source 64 can preferably be
 controlled arbitrarily from outside, in order for the image to be
 represented by the beam 101 to be configured optimally in terms of beam
 quality for the observer, whose eye 100 is represented.
 In the exemplary embodiments in accordance with FIG. 1 and FIG. 3, the beam
 101 is deflected in such a way that, via the eyepiece 18, it projects the
 image it produces directly into the observer's eye 100 or onto the retina
 thereof. The light source 64 used can thus be relatively weak optically.
 In the region of an intermediate image plane 103 of the optical system 33,
 the beams 101 are thus preferably parallel to the optical axis 7 of the
 optical system 33. However, it is not essential for the beam 101 to be
 faded in at the point shown. A variant is also conceivable in which the
 beam is directed into the observer's eye 100 only after the eyepiece 18.
 This variant is expedient particularly since it does not unnecessarily
 increase the required distance of the eye from the eyepiece.
 The object observed is represented symbolically with 22, the purpose of
 this design being, for example, to draw a high-contrast, bright line
 around an object detail 22a. The scope of the invention therefore also
 covers that variant in which the beam 101 is projected not directly into
 the observer's eye 100, but directly onto the object 22, the beam splitter
 32a then having, of course, to act inversely.
 The beam can be used to represent, for example, patient information data
 such as blood pressure, heart rate etc. in graphic form, as indicated in
 FIG. 2.
 By contrast with the first variant, a laser beam 101 is directed there
 straight into the eye, as indicated symbolically. The optician knows the
 measures required to project the beam 101 correctly straight onto the
 retina. A diffusing screen can thereby be eliminated, and the beam can
 apply a high brightness and level of contrast with the correspondingly
 lower amount of energy. The image prescribed by the deflecting device 102a
 is thus produced directly on the retina and is superimposed precisely
 there on the image seen through the main objective 8. In this design, it
 is immaterial which angle the beams make with the optical axis 7, to the
 extent that they impinge only at the desired site on the retina. As an
 alternative to this design, it would be possible to use in the
 intermediate image plane 103 a diffusing grating at which only the
 wavelength region of the laser light is scattered, while the other light
 wavelength regions pass unimpeded, with the result that despite the
 diffusing screen there is no appreciable darkening of the image seen below
 the main objective 8.
 In the example represented, blood pressure and heart rate are represented
 in the area of the object detail 22a which is seen. This patient
 information is obtained by known measuring instruments and, if
 appropriate, conditioned via a data conditioning unit 89 in such a way
 that suitable control data can be fed to the deflecting device 102a in
 order to permit quick real-time operation.
 The example represented in FIG. 3 concerns an image-processing (video)
 evaluation of an image seen through the main objective, for example object
 detail 22a through an image processing device 104a which is coupled to an
 image recording device 9a (for example CCD). The image recording device 9a
 is coupled to the beam path 1 via an imaging optical system and via a beam
 splitter 32b, with the result that the image processing device 104a
 recognizes the object detail 22a being observed. Represented by dashes are
 the image recording device 9b and image processing device 104b, which can
 be provided in addition to or as an alternative to 9a and 104a. In the
 variant drawn with full lines (9a, 104a), in addition to the image of the
 object detail 22a, the image processing device 104a also has available the
 image from the deflecting device 102b which is projected inversely by the
 device 104a. Subsequent correction is therefore easily possible. The
 present example is concerned with detecting contours on the object detail
 22a and enhancing them by means of beam superimposition (101). This makes
 it easier for an operating surgeon, for example, to make out the areas
 involved more quickly and more clearly.
 The beam splitter 32a is arranged in this example approximately centrally
 about an intermediate image plane 103, and is itself provided with a
 surface 108b which scatters to a slight extent, with the result that an
 additional diffusing screen is eliminated.
 In the exemplary stereomicroscope in accordance with FIG. 4, diffusing
 screens 108a are again provided, on which partial images offset by the
 parallax are represented per beam path 1a, 1b relative to the respective
 optical axis 7a, b; said partial images are combined in the observer's
 brain to form a 3-D image. The deflecting devices 102c, d are driven for
 this purpose by an image recognition device 105, possibly with an image
 processing device 104, which receives its image information--possibly via
 a data conditioning unit (89) (not represented) and/or via an image
 memory--from a 3-D image data recording unit or diagnostic data device
 106. The latter preferably operate not in the visible wavelength region as
 do the microscope beam paths, but by means of X-rays, alternating magnetic
 fields, positron beams, ultrasound or the like.
 Thus, for example, it is possible using this design to superimpose
 three-dimensional grid lines calculated from the abovementioned patient
 data on an object detail 22a which is seen three-dimensionally or is to be
 seen theoretically, with the result that an operating surgeon again
 obtains an area of interest to him in a clear and bright fashion and
 highlighted with thin lines.
 Of course, arbitrary combinations of superimposed images are also contained
 within the scope of the invention, such as alphanumeric data, contour
 enhancement and encirclements of areas.
 The variant in accordance with FIG. 5 operates with a micromirror
 deflecting unit having a drive in the tube 33, which directs a laser beam
 101 in the correct position against the observer's eye 100.
 Not shown in more detail, but familiar to the person skilled in the art as
 being within the scope of the invention are variants with colored lasers
 or with electron beams which cause suitable fluorescent screens or the
 like to light up with patterns. Such designs also comprise, if
 appropriate, vector display screens, where lines are frequently retraced
 in each case by the beam. The invention also covers variants in which
 instead of being fed directly to the eye the light beams are firstly led
 to the object being observed and scattered thereon.
 List of Reference Symbols
 This list of reference symbols also contains reference symbols of Figures
 which are contained in the above- mentioned applications since, as
 mentioned, these count as also having been disclosed for combination
 purposes within the framework of this invention. This applies, in
 particular, to the microscopes with special beam paths and beam splitters,
 and to the devices for measuring the magnification and the distance from
 the microscope to the object as well as to microscopes for stereotactic
 operations etc.
 1 a, b First beam path
 2 a, b Second beam path (first beam paths laid geometrically one above
 another)
 3 Mechano-optical switching element
 3a, 3b, 3c Opaque and preferably silvered stop
 3d LCD shutter element
 3e Micromechanical leaf mirror design
 3f LCD exchangeable shutter element
 4 Beam splitters
 4a, 4b Beam splitters
 4c Beam splitter for cutting out the measuring beam
 5 Screen
 5a Semicircular surface
 5b Residual surface of the screen 5
 5c Circular segment surfaces
 5d
 6 Spindle for screen
 7 Central axis
 7a, 7b Central axis
 8 Main objective
 9a Electronic image recording device
 10 Display
 10a Display
 11 a, b Mirror
 12 a, b, c Adjusting device
 13 Zoom
 14 a,b Motor
 15 Reciprocal drive
 16 Supply lead
 17 Light source
 18 Eyepiece
 19 Deflecting mirror
 20 Push rod
 21 Rigid mirror
 22 Object
 22a Object detail
 23 a, b, a', b', c, d Plane plate
 24 Rotary actuator
 25 Linkage
 26
 27
 28
 29
 30 Leaf mirror of 3e
 31 Tube lens
 32 Fade-in element
 32a Beam splitter
 32b Mirror
 32c Second fade-in element
 33 Magnifying optics
 34 Arrows
 35 Further mirror
 36 Actuator
 37 Bar
 38 a, b Deflecting mirrors
 39 Retroprism
 40 Balance weight
 41 Backing plate a, b, c: prismatic with integrated mirror
 42 Color filter
 43 Interval switch
 44 Microprocessor
 45 Measuring array a
 46 Reference array a
 47 Module for image data transmission
 48 Extraneous image data input
 49 Positioning motor for zoom 13: a, b
 50 Connecting lines a-g
 51 Magnification display a, b, c
 42 Cam disk
 53 Coupling
 53a Between positioning motor 49 and zoom 13
 53b Between cam disk 52 and magnification-d [sic] display 51b
 54 Mechanical tap
 55 a, b Pointers
 56 Laser
 57 Measuring beam a, b, c, c1
 58 Reference beam
 59 Arrows for displaceability of the fade-in element 32
 60 Microscope beam path a-e
 61 First deflecting element a
 62 Focusing element a, b
 63 Optical conductor end piece a, b
 64 Light source a
 65 Second deflecting element
 66 Sensor
 67 Distance range a
 68 Connecting line
 69 Distance measuring system
 70 Connection
 71 Magnification measuring unit
 72 Position determining system a, b
 73 Interferometer
 74 Semireflecting mirror
 75 Reflector
 76 Detector
 77 Electromechanical adjusting element
 78 Interferometer control
 79 Grating
 80 Detector CCD
 81 Stages
 82 Microscope
 83 Arrangement for measuring the magnification of the microscope
 84 Arrangement for measuring the object/microscope distance
 85 Position-measuring system for determining the absolute position of the
 microscope in space, and also for the purpose of being able to reach a
 conclusion upon the position of the visual field at the object from
 knowledge of the object/microscope distance
 86 Toolbox for different user programs
 87 Command control element (computer mouse)
 88 Command control element for controlling the movement of the microscope
 (for example foot switch)
 89 Data conditioning unit
 90 Computer (workstation),
 91 Control switch for microscope
 92 Electromechanical control unit for microscope (zoom, focus, etc.)
 93 Object
 94 Second device (for example MRI unit or CT unit)
 95 Superimposing device
 96 Joint on the stand
 97 Adaptive control device
 98 a, b Detection system
 99 Memory
 100 a, b Observer's eye
 101 a, b, c Beams
 102 a, b, c, d Deflecting device
 103 a, b Intermediate image plane
 104 Image processing device
 105 Image recognition device
 105 Diagnostic device
 107 Light valve
 108 a, b Diffusing screen
 109 Test object
 111 Coordinate system
 112 Enhanced contour line
 113 Micromirror deflecting unit
 b Spacing of the measuring beams 57a and 57b
 b ' Spacing of the measuring beams 57a and 57b at the measuring array
 d 1, 2 Stereobasis