DE29824633U1 - Incident light illumination arrangement for a stereo microscope - Google Patents

Description

In stereomicroscopy, the state of the art includes external incident light illumination arrangements in which direct illumination is arranged outside the microscope base body.

These can be halogen lamps with reflector mirrors that are attached to the stereo microscope carrier, the stand column or the stereo microscope base itself and enable oblique incident light illumination.

Cold light illumination is known which is attached to the stand column or the stereo microscope support, for example, and is available as a flexible or semi-rigid single- or multi-arm light guide with focusing optics. Without attachment to the stereo microscope base or the stand, there are single- or multi-arm semi-rigid, so-called goosenecks which are attached exclusively to the cold light source and can be positioned freely in space.
Furthermore, cold light ring lights that can be attached to the front of the stereo microscope are known, which are available as 4-point ring lights or as split ring lights in different diameters and beam angles. All of these external incident light lighting arrangements ensure very differentiated incident light illumination, i.e. the stereomicroscopic object can be optimally "illuminated" according to its surface structure and spatial extent. The disadvantage of these external lighting arrangements is the sometimes considerable installation space in the object area, i.e. the direct view of the object and the freedom for manipulation tasks are sometimes significantly restricted.
Another disadvantage of these external lighting arrangements is that when the stereo microscope is attached to special stands (e.g. machine mounts, floor or wall stands) and the associated free positioning of the stereo microscope in the room, the "light" always has to be "tracked" separately (if the lighting arrangement is not attached to the stereo microscope base body itself). These disadvantages can be avoided if the lighting arrangement itself can be integrated into the stereo microscope base body in a suitable manner in a way that saves as much space as possible.

A whole range of different solutions, some of which have already been published, are known internationally, which aim to use optical instruments (e.g. cameras, video cameras, camcorders, microphones, etc.)

microscopes, stereo microscopes, surgical microscopes) lighting systems.

In stereomicroscopy, the state of the art includes internal incident light illumination arrangements in which the light is coupled into the observation channels within the microscope base body via suitable beam splitter elements (prisms, splitter mirrors) (coaxial incident light principle). The light can be generated and transported via a conventional microscopic incident light device or via a cold light source and light guide until it is then coupled into the observation channels via the above-mentioned beam splitter elements at different points (e.g. above or below the stereomicroscope Pankrat system). In addition to the above-mentioned coaxial illumination arrangements permanently integrated into the stereomicroscope base body, there are also modular units that can be arranged separably between the stereomicroscope Pankrat system and the main objective, for example (e.g. Zeiss stereomicroscopes in telescope design with modular coaxial illumination device and flexible light guide coupling, light guide connection to SCHOTT cold light source KL 1500). The advantage of the coaxial illumination arrangement is that the light is "carried along" with the stereomicroscope base body and, with internal coupling above the stereoscopic Pankrat system, an exact object field adjustment when zooming. With internal coupling below the stereoscopic Pankrat system, the illuminated object field is constantly large and is designed for the maximum object field that can be achieved with the Pankrat. The disadvantage of all the above-mentioned arrangements with the coaxial incident light principle is the formation of strong reflections - especially with highly reflective object surfaces - and the associated deterioration in image contrast due to the light coupling into the observation channels. The state of the art also includes the various arrangement options for suppressing reflections using polarization-optical means (e.g. "anti-flex device" for Zeiss stereomicroscopes in telescope design). The known suppression of reflections using polarization-optical means has the disadvantage that the high absorption capacity of the at least two necessary polarization filters results in a significant reduction in the intensity of illumination. Other internal incident light illumination arrangements modified from this basic principle use only the main objective in front of the telescope-type stereo microscope to couple light into the

observation beam paths or in an azimuthal plane of incidence that is different from the observation channels. Even with these arrangements, which are modified from the basic principle, the problem of reflection formation and reflection elimination using polarization optical means remains. The coaxial incident light principle is preferably only used in stereomicroscopy for flat and level preparations (small depth extension), since with objects with depth extension or objects with surface relief only a poor contrast or a poor spatial visual impression can be achieved with this vertical illumination; a much better contrast and spatial impression can be achieved through the shadow effect that occurs with oblique illumination. The various internal lighting arrangements described above, which work according to the coaxial incident light principle, are used in conventional stereomicroscopes (telescopic design), in surgical microscopes, in medical devices with stereoscopic observation (colposcopes, slit lamps) or sometimes in endoscopes.

The published patent application DE 196 40 352 A1 "Interior lighting device and video microscope system" describes an arrangement for coupling light via beam splitting, as is known in conventional brightfield incident light microscopy. Another arrangement provides for the integration of direct lighting (lamp with reflector mirror) into a video device, whereby the light is then transmitted via optical fibers into the object space with oblique lighting or a further optical fiber coupling via beam splitting into the observation channel (coaxial incident light principle) is provided. The proposed integrated lighting arrangements, some of which are state of the art, only relate to the combination of video microscope system in conjunction with a video device.

The patent document "Operation Microscope" US 4,783,159 describes a surgical microscope in a telescopic design in which an internal lighting arrangement for illuminating the surgical field is integrated. The light is basically coupled between the zoom system (pancrat) and the main objective. The lighting system, which is separately constructed in the surgical microscope, illuminates the surgical field via the optical elements light guide -> separate zoom system -» projection lens -* main objective. By using various optical deflection elements (reflection prisms), the surgical field illumination is distributed via the

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Main lens can be positioned at different locations (either axial or off-axis), which leads to differentiated illumination of the surgical area (e.g. eye).

The patent document "Illumination structure in microscope" EP 0 793 128 A1 describes a microscope (stereomicroscope in parallel design/macroscope) in which an internal illumination system is arranged behind the objective. Various arrangements are described by which the light can be coupled in behind the objective, for example on the optical axis of the objective between the observation channels (2 pairs) with one illumination channel, between the observation channel pairs with 2 or more illumination channels or the light coupling in using areas of the observation optics separated by means of mounts.

The patent document "Incident light object lighting device" DE 39 06 555 A1 describes an (external) lighting device attached to an observation device, which consists of several individual, also individually switchable light sources (e.g. self-illuminators, glass fibers or rear-illuminating apertures) and which are arranged in an at least two-dimensional array, the center of which coincides with the optical axis of the observation imaging optics. _:

The patent document "Epidark illumination system" DE 32 29 768 A1 describes an epidark illumination system, preferably for incident light microscopes, in which light emanating from a light source is passed between a sleeve and an objective lens to illuminate an object (arrangement similar to incident light - dark field arrangements). With this ring-shaped illumination arrangement, a very flat illumination of the object field can be achieved.

The patent specification "Microscope illuminating apparatus" EP 0 504 940 A2 shows various microscope illumination arrangements for incident light, bright field and dark field illumination as well as for transmitted light, bright field and dark field illumination, in which the light coupling into the illumination optical systems is carried out using, among other things, fiber optic means.

EN · ·· Serte4

The patent document "Stereomicroscope" DE 19523712 A1 describes a stereomicroscope (telescope design) which has an observation front lens and an illumination lens which are separated from each other. The focusable observation front lens aligns a beam of observation light emitted from an object point in parallel. The illumination lens projects a beam of illumination light onto the object point. By arranging/focusing the observation and illumination lenses, a position to be illuminated can be changed in accordance with the movement of an object point. The aim of this special arrangement is to achieve illumination that is as coaxial as possible, i.e. to set the smallest possible angle between the optical axis of the illumination light and the optical axis of the observation light (avoiding reflections).

The invention is based on the object of designing the illumination arrangement for stereomicroscopes in such a way that it takes up minimal space and yet the optical-mechanical basic structure is only minimally influenced and a bright, homogeneous and reflection-free illumination of the maximum visible object field is made possible regardless of the position and observation direction of the stereomicroscope.

The problem is solved by the features of the independent claims.
Preferred further training is the subject of the dependent claims.
The invention is explained in more detail below with reference to the schematic drawings. ^{; l}
Show it:

Fig. 1: A bottom view of a stereo microscope according to the invention

Fig. 2: The light guide used according to the invention

Fig. 3: A schematic cutaway side view

Fig. 4: A side view perpendicular to the side view according to Fig.3

Fig. 5: The advantageous adjustment options of the lighting

Fig. 6: Arrangement for contrasting, example fluorescence excitation via the spot

- Lighting equipment

By integrating a fiber optic illumination arrangement with focusing optics that is completely separate from the observation beam paths into the stereo microscope base body, preferably the arrangement of two "spots" in a

♦*

By arranging the plane orthogonal to the observation plane, an arrangement is achieved which satisfies the above-mentioned task.

In Fig. 1, B1, B2 are the exit openings or objective ends of two observation channels of a Greenough stereomicroscope M1 in the direction of the object.
The microscope Ml is connected to a stand S via a microscope carrier MT. The exit openings BL1, BL2 of two light sources are arranged perpendicular to the connecting axis of the observation channels.

This orthogonal arrangement of the illumination channels prevents a disturbing image of the illumination channel after reflection in the object plane (critical for highly reflective objects) in the second observation channel and the associated deterioration in contrast. Furthermore, to avoid reflections in the entire stereomicroscope zoom range for highly reflective objects and to improve the "stereoscopic contrast", the illumination arrangement, as shown in Fig. 4, 5, is advantageously arranged at an angle of * 0°, i.e. at an angle of « 10°... 12° (= half angle to the center) to the optical axis of the microscope. Focusing optics FO ₁ connected upstream of the light guides, which illuminate the object plane, can be designed both as fixed systems (illumination of the maximum object field diameter) and in principle also as zoom systems (e.g. mechanically coupled to the observation zoom system) with a variable object field diameter.

To achieve maximum illumination in the object plane, it is advantageous if the illumination is provided by a twin light guide LL (see Fig. 2) equipped with focusing optics FO, and an overlay of both "individual spots" takes place in the object plane. The two individual fiber bundles of the branch V of the flexible twin light guide LL unite within the stereo microscope base body and leave the stereo microscope base body as a continuous (avoiding light losses), single-arm and flexible light guide - provided with a sufficient length - via a strain relief ZE at a suitable point. The light guide is then connected to an external cold light source LQ via a standardized end piece ST. Flexible light guides can be glass light guides or plastic light guides as well as liquid light guides (particularly

advantageously used in fluorescent lighting arrangements, see also Fig. 6).

A possible arrangement of the integrated fiber optic illumination system in a Greenough-type stereomicroscope in a plane parallel to that of the observation channels (sectional view through an illumination channel) is shown in Fig. 3.

The microscope Ml is only indicated by dashed lines and without a tube.
The light guide LL is coupled into the microscope housing from above and has a strain relief ZE.

Its branched part V advantageously runs completely inside the microscope housing between the lens groups L of the zoom system of the microscope, which are movable on guides F and partially fixed, without the observation beam paths being vignetting as a result.

Fig. 4 shows that the two light guide ends provided with focusing optics FO form an angle to the optical axis of the microscope and thus advantageously overlap with respect to their illumination spots BS, so that a uniform bright illumination of the object in the object plane OE over the entire maximum object field OF is achieved.

This lighting principle is suitable for both Greenough-style stereo microscopes and, in principle, for telescope-style stereo microscopes. To avoid reflections (a disadvantage of the known coaxial stereo microscope lighting arrangements), the lighting can also be implemented outside of attachment systems (Greenough systems) or lenses (telescope systems, typical lighting arrangements for surgical microscopes). A permanent installation of the lighting focusing optics provides optimal illumination of the object field for the stereo microscope without an attachment system (Greenough design) or only for one attachment system / lens. To adapt to different lenses / attachment systems, the lighting focusing optics must be moved and swiveled using mechanical guide and adjustment elements.
This is shown in Fig. 5.

Here, illumination optics FO are shown that can be swiveled and radially moved and focused in various directions using control elements. The illumination focusing, i.e. the variable adjustment of the illumination spots to the observable object field diameter, is implemented using a focusing control FS, which is either mechanically coupled to the observation zoom system or carried out electronically via a motor. Different advantageous variants are described below.

(A] - Swiveling the lighting focusing optics (variation of the angle of incidence of the light spots in conjunction with [I]), operation with suitable external controls

[b] - Radial displacement of the illumination focusing optics (variation of the

Angle of incidence of the light spots in conjunction with [Ä] ), operation with suitable external controls

[c] - Variation of the illuminated object field diameter by focusing;

Variation of the distance between the light guide output and the focusing optics with manual operation or light guide coupling into a separate illumination zoom system, which is mechanically coupled to the observation zoom or is operated by an external control FS with motor drive

The illumination focusing system can advantageously be mechanically or electrically coupled to the zoom drive of the stereo microscope, i.e. when the observation zoom system is activated, the illuminated object field diameter is automatically and variably adjusted.

This illumination principle is also suitable for microscopic contrast methods. Fig. 6 shows an example of the arrangement for fluorescence excitation using the spot illumination device. Starting from the arrangements described in Fig. 4 or Fig. 5, if a filter holder FAA for holding and changing filters is installed between the light guide end piece ST and the light source LQ, in the case of fluorescence excitation for holding and changing excitation filters A, between

switched (this filter change point is already present in many light sources on the market - especially cold light sources), fluorescence excitation is possible via the spot focusing optics FO. If a filter holder for blocking filters FAS is also accommodated in the observation channels for changing blocking filters S, observation can be carried out with very good stereoscopic fluorescence contrast, i.e. the complete decoupling of illumination and observation channels enables high-contrast and reflection-free observation through oblique illumination. Suitable light sources for fluorescence excitation in the visible spectral range are halogen cold light sources (e.g. SCHOTT cold light source KL 1500) or XBO (xenon ultra-high pressure lamp^ e.g. XBO 75 W) and for UV fluorescence excitation HBO (mercury ultra-high pressure lamps, e.g. HBO 50 W or HBO 100 W). Filter manufacturers and stereo microscope manufacturers offer a whole range of different filter sets (consisting of excitation and blocking filters) for the most diverse application tasks of fluorescence stereomicroscopy. Coupling light via a light guide is advantageous for stereomicroscopic observation in any spatial direction (e.g. special stands for restorers) with fluorescence excitation, since the above-mentioned high-pressure lamps would disturb the observer with their considerable heat development (risk of burns if touched) if rigidly coupled to the stereomicroscope without a light guide and, in addition, according to the manufacturer's instructions, the high-pressure lamps may only ever be operated in a vertical installation position (severe inclinations will destroy these lamps). In the inventive arrangement according to Fig. 6, the light source can remain in a fixed location (for example, attached to the special stand) and the stereo microscope - connected to the light source via the light guide - can be oriented in any spatial position.

Test results:

A reflected light illumination system - as shown in Fig. 1 to Fig. 4 - was integrated into the ZEISS Stemi 1000 base body while maintaining the working distance of 4" (110 mm).

The two illumination optics - arranged in a north-south direction - were positioned at an angle of 2x8° in order to achieve oblique incident light illumination with extensive decoupling from the observation channels. This arrangement achieved significantly better image quality (no disturbing incident light reflections in the upper zoom range) than with complex coaxial incident light illumination arrangements (reflection minimization using polarization optical means).

The following performance characteristics were demonstrated on the prototype:

Bright, homogeneous illumination, illumination with SCHOTT KL 150Oe cold light source; an illumination angle of 2x8° was realized on the prototype, thus a much smaller illumination angle could be achieved than with externally attached lights with very oblique light incidence (e.g. SCHOTT point or ring light: 18°, light 10: 35°).

Considerably higher contrast illumination than classic, coaxial illumination arrangements with beam splitting (illumination angle 0°, problem of brightening single reflections, which cannot be completely eliminated despite antiflex arrangement) through complete separation of the observation and illumination beam paths, ;

Due to the complete integration of the lighting into the stereo microscope base, the full working distance (4" for the Stemi 1000) is maintained: Advantage over externally attached cold light components, which limit the working distance and prevent the direct, unobstructed view of the object being observed.

All external stereo microscope interfaces remain intact (0 76 mm as internationally standardized mount - 0, mount - 0 for external cold light components, coupling thread for attachment systems), so there are no restrictions on the previous variability,

Thanks to the integration, the lighting does not need to be adjusted when the observation location changes (e.g. special stands for MEG applications, scanning large object fields with boom stands e.g. in the textile industry, restorer stands with arbitrary spatial orientation of the stereo microscope base body) and the clear view of the object is maintained;

Due to the extremely compact stereomicroscope basic structure, the following alternatives are seen as modifications to the above-mentioned embodiments (Fig. 1 to Fig. 4) with necessary structural restrictions for the spot illumination:

- No lighting channel, lighting only with a "spot" from N or S direction,

- Instead of the flexible light guide, a light guide rod or an internally mirrored light guide tube could also be used if the light output is sufficient, to which a flexible standard light guide (e.g. for KL 200) can be coupled at the upper end in an interchangeable manner (an advantage I if the transmission loss is acceptable).

- No focusing optics, i.e. due to the high fiber optic aperture (A * 0.66 for fiber - type A2) an object field of »160 mm is illuminated at a free working distance of 90 mm (relatively homogeneous illumination « 0 100 mm), the visible illuminance in the field of view is then noticeably lower, particularly in the upper zoom range, than with an adapted illumination of the object field of view, but it is still considered sufficient (advantage of the large-area illumination of the object field when manipulating and positioning objects with the naked eye, i.e. the "light" is always provided by the stemi).

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Claims (19)

1. Illumination arrangement for a stereomicroscope, preferably of the Greenough type, consisting of at least one, preferably two illumination channels arranged in a plane substantially orthogonal to the plane through the plane of the two observation channels. 2. Illumination arrangement according to claim 1, in a stereomicroscope of the Geenough type, with two light channels in the interior of the microscope housing outside the observation beam paths. 3. Illumination arrangement according to at least one of the preceding claims, wherein the light channels are guided around the observation optics. 4. Illumination arrangement according to at least one of claims 1-3, wherein the illumination direction is at an angle to the optical axis of the microscope, so that no direct light falls into the observation channels. 5. Lighting arrangement according to at least one of the preceding claims, wherein the illumination is provided via at least one light guide. 6. Lighting arrangement according to at least one of the preceding claims, wherein the light guide is a flexible glass light guide and/or plastic light guide and/or liquid light guide. 7. Illumination arrangement according to at least one of the preceding claims, wherein the light guide runs at least partially inside the microscope housing. 8. Lighting arrangement according to at least one of the preceding claims, wherein the illumination is provided via the light guide ends. 9. Lighting arrangement according to at least one of the preceding claims, wherein the illumination is provided via an illumination optics arranged downstream of the light guide end. 10. Illumination arrangement according to at least one of the preceding claims, wherein the illumination optics are arranged as a zoom system so as to be adjustable and/or displaceable and/or pivotable with respect to the image scale. 11. Lighting arrangement according to at least one of the preceding claims, wherein a manually operable and/or motor-operable control is provided for adjusting the lighting optics. 12. Illumination arrangement according to at least one of the preceding claims, wherein when adjusting the illumination optics as a zoom system, this adjustment is coupled with the adjustment of the microscope zoom system. 13. Lighting arrangement according to at least one of the preceding claims, wherein the illumination is provided via a light guide which branches to generate the two light channels. 14. Illumination arrangement according to claim 13, wherein the branch is located entirely inside the microscope housing. 15. Lighting arrangement according to one of claims 13 or 14, wherein the branches of the light guide are guided around the observation channels. 16. Illumination arrangement according to at least one of the preceding claims, wherein the light guide is connected to a cold light source arranged outside the microscope. 17. Illumination arrangement according to at least one of the preceding claims, wherein fluorescence excitation occurs via the illumination channels. 18. Illumination arrangement according to claim 17, wherein at least one light guide is connected to a light source arranged outside the microscope, which is suitable for fluorescence excitation in combination with exchangeable excitation filters. 19. Lighting arrangement according to one of claims 17 or 18, wherein a filter holder for excitation filters is provided between the light source and the light guide and a filter holder for blocking filters is provided in the observation beam path.