DE102017216754B4 - Surgical microscope with an illumination device - Google Patents

Abstract

Surgical microscope (130) with an illumination device (100, 180) for illuminating an object plane (132), comprising a light source (101) for emitting illumination light in a first wavelength range, illumination optics with an optical coupling element (120), the illumination light being directed along a Beam path (102) is guided from the light source (101) to the optical coupling element (120) and is guided via the illumination optics to the object plane (132), an illumination filter (110) which is in the beam path (102) between the light source (101 ) and the optical coupling element (120) is arranged and has a pass band in a second wavelength range which is suitable as the excitation wavelength range of a fluorescent dye, the beam path (102) being in at least one region between the light source (101) and the optical coupling element (120). is encapsulated in such a way that illumination light emitted by the light source (101) only passes through the illumination filter (110) to the coupling element (120).

Description

The invention relates to a surgical microscope with an illumination device for illuminating an object area in fluorescence diagnostics.

One way to make tumors visible to the surgeon using a surgical microscope is through fluorescence diagnostics.

To examine and treat tumors, it is known to administer a fluorescent dye to a patient that accumulates selectively in tumor cells. By illuminating the fluorescent dye with a certain wavelength, referred to as the excitation wavelength or excitation light, its molecules are stimulated to fluoresce. Such fluorescent light can be detected by an optical system so that a tumor can be localized. The fluorescent dyes do not accumulate in healthy tissue, so that the diseased tissue can be recognized by a significantly higher fluorescence. Examples of a fluorescent dye are protoporphyrin IX.

The fluorescent light emitted by the fluorescent dye lies in a different wavelength spectrum than the excitation light. At least one filter is therefore arranged in the observation beam path of the surgical microscope so that the emitted wavelength spectrum of the fluorescent light can be separated from the wavelength spectrum of the excitation light. This means that the tumor tissue can be distinguished from the healthy tissue.

However, the intensity of the fluorescent light emitted is not the same for all fluorescent dyes or tumor types. There are tumors that only fluoresce very weakly. This very weakly emitted fluorescent light is not easy to visualize in the respective wavelengths in a surgical microscope. In some applications, detection and registration of this very weak fluorescent light is only possible with very sensitive camera chips.

If only a small portion of the illumination light emitted by the light source, which lies in the wavelength spectrum of the fluorescent light, reaches the object plane, then an observer can no longer distinguish whether it is the weak fluorescent light emitted by the fluorescent dye or light from the illumination device acts.

In DE 10 2009 025 127 A1 describes an illumination device for an optical observation device that can be operated in a fluorescence mode. The lighting device comprises a broadband light source for illuminating an observation object and a narrowband light source for stimulating fluorescence in the observation object. Out of DE 10 2010 044 503 A1 , DE 10 2008 004 596 A1 and WO 2017/007690 A1 Fluorescence microscopes with broadband light sources and filters for separating the wavelength spectrum of the excitation light from the wavelength spectrum of the broadband light source are also known. In DE 10 2009 025 127 A1 and WO 2017/007690 A1 The housing of the respective lighting device is also shown or described.

The object of the invention is to provide an improved surgical microscope in which the observation of tissue that fluoresces with very weak intensity is possible.

The task is solved by a device with the features of independent claim 1. Advantageous developments of the invention are described in the subclaims.

According to the invention, a surgical microscope with an illumination device for illuminating an object plane comprises a light source for emitting illuminating light in a first wavelength range, an illumination optics with a coupling element, the illumination light being guided along a beam path from the light source to the optical coupling element and via the illumination optics to the object plane is guided. An illumination filter is arranged in the beam path between the light source and the optical coupling element and has a pass band in a second wavelength range, which is suitable as the excitation wavelength range of a fluorescent dye. The beam path is encapsulated in at least one area between the light source and the optical coupling element in such a way that illumination light emitted by the light source only reaches the coupling element through the illumination filter.

A light source generates illuminating light in a first wavelength range. The illuminating light is guided along a beam path to an object plane. An illumination filter, a coupling element and illumination optics are arranged in the beam path. The illumination light is passed through the illumination filter. The illumination filter has a pass band in a second wavelength range, so that a precisely defined second wavelength range is cut out of the first wavelength range. This second wave Length range forms an excitation wavelength range for fluorescence observation. The illumination light emerging from the filter in this second wavelength range is coupled into the illumination optics via a coupling element and guided through the illumination optics to illuminate an object plane.

The illumination light directed to the object plane is used as excitation light for fluorescence observation. For this purpose, only the illumination light guided through the illumination filter should be directed to the object plane in the second wavelength range. For this purpose, only the illumination light filtered through the illumination filter should enter the optical coupling element.

The beam path is therefore encapsulated in at least one area between the light source and the optical coupling element.

The encapsulation along a region of the beam path between the light source and the coupling element prevents light from being emitted into the lighting device through reflection or scattering, which could be coupled back into the beam path at another point.

The encapsulation forms a complete enclosure for this area of the beam path, so that no light can penetrate from the beam path to the outside or enter the beam path from outside. The penetration of scattered light, reflected light, or other extraneous light that could enter this encapsulated section of the beam path from outside is reliably prevented.

If the beam path is encapsulated in a section between the light source and the illumination filter, the illumination light emitted by the light source is directed to the illumination filter in the first wavelength range within the encapsulation. The encapsulation therefore prevents ambient light or extraneous light that is not generated by the light source from reaching the lighting filter. Only the light generated by the light source is guided along the beam path to the illumination filter.

Encapsulation in a section between the illumination filter and the coupling element ensures that only the illumination light emerging through the illumination filter in the second wavelength range can reach the coupling element. The penetration of scattered light, reflected light, or other extraneous light that could enter this section of the beam path between the lighting filter and the coupling element from the outside is reliably prevented.

This means that only light of the second wavelength range of the precisely defined illumination filter is coupled into the coupling element and guided through the illumination optics to the object plane in order to stimulate the fluorescent dye in a tumor.

External light that could penetrate the lighting device in some way, enters the lighting device through reflection or scattering, or is generated by a possible additional light source, cannot reach the coupling element.

The surgical site is advantageously illuminated in a wavelength-selective manner without disturbing extraneous light, reflected light or scattered light. This ensures that the fluorescent light detectable through observation of the surgical microscope is generated exclusively by the fluorescent dye in the tumor and is not generated by the lighting device. The light present in the object plane when viewing fluorescence through the surgical microscope is in two separate wavelength ranges. The first wavelength range represents the excitation light, the second wavelength range represents the fluorescent light detected in the observation. This also makes it possible to observe and detect tissue that fluoresces at a very weak intensity.

In one embodiment of the invention, the beam path is designed to be encapsulated in a first region between the illumination filter and the optical coupling element.

The encapsulation between the illumination filter and the coupling element ensures that only the illumination light emerging through the illumination filter in the second wavelength range can reach the coupling element. The penetration of scattered light, reflected light, or other extraneous light that could enter this section of the beam path between the lighting filter and the coupling element from the outside is reliably prevented.

In one embodiment of the invention, the beam path is designed to be encapsulated in a second region between the light source and the illumination filter.

The encapsulation in this second area prevents ambient light or extraneous light that is not generated by the light source from reaching the lighting filter. Only the light generated by the light source is captured along the beam path to the lighting filter. It also ensures that no light between the light source and the lighting filter is emitted into the lighting device through reflection or scattering.

In one embodiment of the invention, the beam path between the light source and the optical coupling element is guided through an encapsulation, the encapsulation having a recess into which the illumination filter can be inserted.

The complete encapsulation between the light source and the optical coupling element can further improve the escape of scattered light or reflected light and the penetration of extraneous light into the beam path.

The illumination light emitted by the light source in the first wavelength range is guided within the encapsulation to the illumination filter. The encapsulation therefore prevents ambient light or extraneous light that is not generated by the light source from reaching the lighting filter. Only the light generated by the light source is guided along the beam path to the illumination filter.

The further encapsulation between the illumination filter and the coupling element ensures that only the illumination light emerging through the illumination filter can reach the coupling element in the second wavelength range. The penetration of scattered light, reflected light, or other extraneous light that could enter this section of the beam path between the lighting filter and the coupling element from the outside is reliably prevented.

The encapsulation has a recess into which the lighting filter can be inserted. The illumination filter can be inserted into the beam path and removed again. This arrangement allows the lighting filter to be advantageously replaced. This is particularly advantageous if the lighting filter is arranged on a filter changer, for example a filter wheel. It is advantageous for several filters to achieve wavelength-selective illumination of the object plane without disturbing reflected light or scattered light.

In one embodiment of the invention, the encapsulation is formed by a scattered light sleeve.

A scattered light sleeve forms an elongated and solid covering of the beam path and encapsulates the beam path. A scattered light sleeve can have a cross-section of any shape. A round cross section has the advantage that the scattered light sleeve is easier to produce. The scattered light sleeve can advantageously be manufactured as a component that can be easily assembled or retrofitted in a beam path.

In one embodiment of the invention, the scattered light sleeve is designed in two parts.

A two-part scattered light sleeve simplifies the creation of a recess into which the lighting filter can be inserted. Further advantages include easy assembly and simpler individual parts, for example simple and inexpensive turned parts.

In one embodiment of the invention, one surface of the scattered light sleeve is designed as a thread.

Multiple reflections can occur on the thread, thus reducing the amount of light that hits it and the amount of scattered light. A thread can also be used to create a solid mechanical and light-tight connection to another component, such as the coupling element or the light source. Threads are easy to produce.

In one embodiment of the invention, the scattered light sleeve is designed as a cylinder.

A cylinder is inexpensive and easy to produce, for example by sawing off a pipe.

In one embodiment of the invention, the scattered light sleeve is conical.

Thanks to the conical shape of the scattered light sleeve, it can be adapted very well to a convergent beam path.

In one embodiment of the invention, a surface of the scattered light sleeve is designed to be stepped.

The gradation can result in multiple reflections, thus reducing the incident light and the scattered light. The gradation can create cylindrical outer and inner surfaces on both end faces, which facilitate assembly and connection to another component, for example to the coupling element or to the light source.

In one embodiment of the invention, an end face of the scattered light sleeve has a bristle comb.

The bristle comb can close the gap between a permanently mounted scattered light sleeve and a movable element, for example a Filter wheel or a filter slide, are optically sealed, and still allow relative movement of the components. The mobility of the filter wheel or filter slide is only slightly affected by the bristle friction.

In one embodiment of the invention, a surface of the scattered light sleeve is black.

A black surface absorbs light and therefore reduces reflection and scattering. The black color can be applied by anodizing, painting or plasma chemically.

In one embodiment of the invention, a surface has grooves, grooves or scales, so that a rough surface is formed with an arithmetic mean roughness Ra > 0.1mm.

Multiple reflections can occur on a rough surface, resulting in a reduction in reflected light and scattered light.

In one embodiment of the invention, the illumination filter has a pass band in a wavelength range of 400 nm to 435 nm.

Illumination light in this wavelength range is particularly suitable for fluorescence excitation for protoporphyrin IX.

In one embodiment of the invention, the illumination filter has a pass band in a wavelength range of 400 nm to 800 nm.

Illumination light in this wavelength range or a portion of this wavelength range is particularly suitable when using the fluorescent dye indocyanine green.

In one embodiment of the invention, the illumination filter has a pass band in a wavelength range of 380 nm to 440 nm.

This excitation wavelength enables the fluorescent light examination of a tissue area in the blue spectral range. Illumination light in this wavelength range or a portion of this wavelength range forms an excitation light for a fluorescent dye that is particularly sensitive to a wavelength around 405 nm.

In one embodiment of the invention, the lighting filter is arranged on a filter changer.

Several lighting filters can be arranged on a filter changer. Different lighting modes can advantageously be set, each with different lighting wavelengths.

In one embodiment of the invention, the optical coupling element is a light guide.

When the illumination light is coupled into a light guide, the illumination light can be generated outside the surgical microscope. The light source is easier to access and can therefore be replaced easily. Heat generation from the light source is separated from the observation optics of the surgical microscope. The illumination device forms a cold light source. The surgical microscope can be constructed more compactly.

In one embodiment of the invention, the light source lights up continuously.

A continuously shining light source is understood to mean a constantly shining light source. A pulsed light source can only be viewed as continuously luminous if an observer cannot optically differentiate the pulses, so that an observer perceives the light source as continuously and constantly luminous. For example, an LED can be controlled using pulse width modulation to control the brightness of the light source. However, an observer does not perceive any pulses or flashes, but rather perceives the LED to be constantly and continuously lit. When viewing a surgical site with the naked eye, a pulsating or flashing illumination light would be disruptive and uncomfortable.

• 1 eine Beleuchtungsvorrichtung für ein Operationsmikroskop in einer schematischen Darstellung;
• 2 die Beleuchtungsvorrichtung gemäß 1 mit einem Streulichtanteil in einer schematischen Darstellung;
• 3 die Beleuchtungsvorrichtung gemäß 1 mit einem durch Streulichthülsen gekapselten Strahlengang;
• 4 ein erstes Ausführungsbeispiel einer Streulichthülse in einer Schnittdarstellung;
• 5 ein zweites Ausführungsbeispiel einer Streulichthülse in einer Schnittdarstellung;
• 6 ein drittes Ausführungsbeispiel einer Streulichthülse in einer Schnittdarstellung.

Further advantages and features of the invention are explained with reference to the following drawings, in which:

• 1 an illumination device for a surgical microscope in a schematic representation;
• 2 the lighting device according to 1 with a scattered light component in a schematic representation;
• 3 the lighting device according to 1 with a beam path encapsulated by scattered light sleeves;
• 4 a first exemplary embodiment of a scattered light sleeve in a sectional view;
• 5 a second embodiment of a scattered light sleeve in a sectional view;
• 6 a third embodiment of a scattered light sleeve in a sectional view.

The 1 shows a lighting device for a surgical microscope in a schematic representation.

A lighting device 100 comprises a light source 101, a filter changer, which is designed as a filter wheel 110, with a first lighting filter 111 and a second lighting filter 112, an optical coupling element 120 and a light guide 121.

The illumination light emitted by the light source 101 is guided in a convergent beam path 102 to the optical coupling element 120. The illumination beam path 102 is guided through the first illumination filter 111. The first lighting filter 111 is arranged on the filter wheel 110. The filter wheel 110 includes the further lighting filter 112. The filter wheel 110 is rotatably mounted on an axle 113. This is shown schematically by arrow 114.

The illumination light coupled into the optical coupling element 120 is guided via a light guide 121 to a surgical microscope 130. The surgical microscope 130 includes a main lens (not shown), illumination optics and observation optics. The illumination light supplied via the light guide 121 is formed into an illumination light cone 131 via the illumination optics of the surgical microscope 130 and forms the illumination for an object plane 132. The surgical microscope 130 is designed for the illumination and observation of an operation site. The surgical site includes a tumor.

The lighting device 100 may comprise further optical elements not shown, for example lenses, apertures, beam splitters and/or further filters.

The light source 101 may be an incandescent lamp, a halogen or xenon light source. The light source 101 can also be formed by an LED light source.

The filter wheel 110 may include a single illumination filter or multiple illumination filters. The filter wheel 110 can also have an opening without a filter element, through which the illuminating light reaches the optical coupling element 120 directly. The filter wheel 110 can alternatively also be formed by a filter slide, in which a single or multiple filters can be inserted linearly along an axis into the beam path.

The first illumination filter 111 has a pass band in a precisely defined wavelength range, which is suitable for exciting a fluorescent dye in the tumor. The first illumination filter 111 is therefore also referred to as an excitation filter.

An example of a passband is a wavelength range from 400 nm to 435 nm as the excitation range for protoporphyrin IX. For this purpose, a dye called 5-ALA is supplied to the body, which is converted into protoporphyrin IX through metabolic processes in the body and thus forms a tumor marker.

The second illumination filter 112 has a pass band that is different from the wavelength range of the first illumination filter 111. For example, the second illumination filter 112 has a passband for another fluorescent dye. In an alternative embodiment, the filter wheel 110 can also have only one opening instead of the second illumination filter 112, for example if the illumination light emitted by the light source 101 is intended to illuminate the surgical site without filtering.

The optical coupling element 120 can be formed by a lens or a light guide. It is also conceivable that the illuminating light is coupled directly into the light guide 121. The light guide 121 can be formed by an optical fiber or a light guide rod. A light guide rod is advantageous because the entire rod as a solid material can transmit the light and therefore small losses in brightness occur. An optical fiber is advantageous because it can also transport the light along curved paths, thus enabling a very flexible design of the lighting device.

The surgical microscope 130 can be a conventional optical stereo surgical microscope with a main objective, magnifying optics and eyepieces, or a purely digital surgical microscope in which an object plane is recorded by one or more cameras, the image of which is displayed on a screen. The surgical microscope 130 can also form a hybrid system, a mixture of a conventional surgical microscope and a digital surgical microscope.

The 2 shows the lighting device according to 1 with a scattered light component in a schematic representation.

In an ideal lighting device 100, all of the illuminating light generated in the light source 101 is passed through the first lighting filter 111. In this case, only light of the wavelength range is used of the precisely defined illumination filter 111 is coupled into the light guide 121 via the coupling element 120 and illuminates the surgical site via the illumination optics of the surgical microscope 130 and thus stimulates the fluorescent dye in the tumor.

In one embodiment, a light source 101, which is designed as a xenon light source, generates illumination light in a wavelength range of 370 nm to 800 nm. The illumination filter 111 has a pass range of 400 nm to 435 nm as an excitation range for protoporphyrin IX. If all of the illumination light is passed through the illumination filter 111, the surgical site is illuminated exclusively with illumination light in the wavelength range from 400 nm to 435 nm. This causes the fluorescent dye in the tumor to be stimulated.

However, the light source 101 already represents a source of interference. Illumination light in a wavelength range outside the pass range of the filter 111 is reflected and/or scattered within the lighting device on components or the housing. This reflected and/or scattered illumination light, which is not guided through the illumination filter 111, is represented schematically by a first scattered light 140. The first scattered light 140 reaches the optical coupling element 120 and is guided via the light guide 121 and the illumination optics of the surgical microscope 130 to the object plane 132 of the surgical site. This means that illumination light in a wavelength range outside the wavelength range of 400 nm to 435 nm defined by the illumination filter 111 also reaches the object plane, onto the surgical site and onto the tumor. Thus, too much illumination light, which was not previously passed through the illumination filter 111, reaches the light guide and thus reaches the fluorescent dye in addition to the excitation light.

In the observation beam path of the surgical microscope 130, when viewing the object plane 132, it is therefore not possible to clearly distinguish whether the observed light is actually fluorescent light, which is emitted by the excitation of the fluorescent dye in the tumor, or the first scattered light 140 from the Lighting device 100 is. This applies both when viewing the object plane 132 through the eyepieces of the surgical microscope 130 and when viewing it through a camera.

The 3 shows the lighting device according to 1 with a beam path encapsulated by scattered light sleeves.

A lighting device 180 according to 3 has the same components as the lighting device according to 1 and the 2 . The lighting device 180 according to 3 differs from the lighting device 100 according to the 1 and the 2 in that the beam path 102 is guided in an encapsulated manner in a first region between the illumination filter 111 and the optical coupling element 120 and is additionally guided in an encapsulated manner in a second region between the light source 101 and the illumination filter 111.

The encapsulation is formed by a scattered light sleeve, which is designed in two parts. The convergent first section of the beam path 102 between the light source 101 and the first illumination filter 111 arranged on the filter wheel 110 is encapsulated by a first scattered light sleeve 150. The convergent second section of the beam path 102 between the first illumination filter 111 and the optical coupling element 120 is encapsulated by a second scattered light sleeve 151.

Scattered light or reflected light that arises between the light source 101 and the first illumination filter 111 is shown schematically as a second scattered light 141. The second scattered light 141 is either absorbed by the first scattered light sleeve 150 or reflected in such a way that it passes through the first illumination filter 111.

A third scattered light 142 schematically shows scattered light or reflected light that is generated between the first illumination filter 111 and the coupling element 120. The third scattered light 142 is either absorbed or reflected by the second scattered light sleeve 151 in such a way that it is guided to the coupling element 120.

Light that hits the second scattered light sleeve 151 from outside is shown schematically by a fourth scattered light 143. The first scattered light sleeve 150 and the second scattered light sleeve 151 effectively prevent ambient light, or light reflected or scattered in the lighting device 100, from entering the beam path 102 and being coupled into the light guide 121 via the optical coupling element 120.

The first scattered light sleeve 150 can be connected to the light source 101 in a light-tight manner. Likewise, the second scattered light sleeve 151 can be connected to the coupling element 120 in a light-tight manner. These connections are static because there is no mechanical relative movement between these components.

However, a mechanical movement takes place between the filter wheel 110 and a first forehead side of the first scattered light sleeve 150, as well as a second end face of the second scattered light sleeve 151.

Therefore, a first gap 160 is present between the first end face of the first scattered light sleeve 150 and the filter wheel 110. A second gap 161 is formed between the filter wheel 110 and the second end face of the second scattered light sleeve 151. The first gap 160 and the second gap 161 are present so that the filter wheel 110 can carry out a rotational movement about the axis 113 and is not jammed. This gap is very small, for example less than 0.1 mm, in order to largely avoid the penetration of scattered light into the beam path 102.

A bristle ring can advantageously be arranged on the first end face of the first scattered light sleeve 150 and on the second end face of the second scattered light sleeve 151 in order to effectively prevent the penetration of scattered light through the first gap 160 or the second gap 161. An example of such a bristle wreath is in 6 shown. As an alternative to the bristle ring, a flexible sealing lip or a felt element can also be arranged that creates a light-tight seal and only exerts a low frictional force on the filter wheel 110.

The encapsulation can also be designed such that the filter wheel 110 is completely or at least partially enclosed in the encapsulated area.

In one embodiment, the beam path 102 is guided between the light source and the optical coupling element 120 through a one-piece encapsulation, the encapsulation having a recess into which the filter wheel 110 with the illumination filter 111 can be inserted. The one-piece encapsulation thus includes the first scattered light sleeve 150 and the second scattered light sleeve 151.

In one embodiment, only the second scattered light sleeve 151 is arranged in the beam path 102. This ensures that only the illumination light emerging through the illumination filter 111 in the second wavelength range can reach the coupling element 120. The penetration of extraneous light that could enter this section of the beam path 102 between the lighting filter 111 and the coupling element 120 from the outside is reliably prevented. The scattered light sleeve 151 ensures that light, which could enter the lighting device from outside or illumination light that is scattered or reflected in the lighting device and is not guided through the lighting filter 111, is not coupled into the coupling element 120.

In a further embodiment, only the first scattered light sleeve 150 is arranged in the beam path 102. The first scattered light sleeve 150 prevents ambient light or extraneous light that is not generated by the light source 101 from reaching the illumination filter 111. Only the light emitted by the light source 101 is guided along the beam path 102 to the illumination filter 111. The first scattered light sleeve 150 prevents light from being emitted into the illumination device 180 along the beam path 102 between the light source 101 and the illumination filter 111 by reflection or scattering.

The 4 shows a first exemplary embodiment of a scattered light sleeve in a sectional view.

A first scattered light sleeve 200 is designed as a cylinder. The width of the lateral surface 201 of the first scattered light sleeve 200 takes up approximately 10% of the diameter. As a result, the first scattered light sleeve 200 has a relatively wide first end face 202 and a second end face 205. An additional sealing element, for example a flexible sealing lip, a felt element or a bristle element, can advantageously be arranged on the first end face 202 or on the second end face 205 in order to further improve the sealing effect. The outer surface is designed as an external thread 204, the inside of the cylinder is designed as an internal thread 203.

The first scattered light sleeve can thus advantageously be screwed onto the light source or onto the coupling element in order to further improve the light tightness at this connection point. The internal thread 203 or the external thread 204 can advantageously be designed as a light trap in order to effectively absorb scattered light. In combination with a light-reducing surface, light is absorbed particularly well because it hits the surface multiple times. The internal thread 203 and/or the external thread 204 can have a high degree of roughness. The surface can have grooves, grooves or scales, so that a rough surface is formed with an arithmetic mean roughness value Ra > 0.1mm.

The first scattered light sleeve 200 can be anodized black or painted to absorb incident light. The coloring can also be done using plasma chemistry.

The first scattered light sleeve 200 can be made of plastic or metal. Plastic is light and can be produced already colored. Metal has good thermal conductivity. The mecha Niche machining of a cylindrical scattered light sleeve is possible on a lathe. A cylindrical diffuser light sleeve can be manufactured cost-effectively by the meter.

The 5 shows a second embodiment of a scattered light sleeve in a sectional view.

A second scattered light sleeve 300 is conical. A first diameter of a first end face 203 is larger than a second diameter of a second end face 205. Due to the essentially conical shape of a lateral surface 301, the second scattered light sleeve 300 is particularly well adapted to a convergent beam path. The cone shell has step-shaped shoulders on its outer surface 304 and on its inner surface 303. This allows reflected light and scattered light to be absorbed more effectively. The surface can be colored black to reduce light. The step-shaped shoulders can be designed in such a way that the lateral surfaces of the steps are each cylindrical.

Due to the step-shaped design, the adjacent step on the first end face 203 and on the second end face 302 is cylindrical. This means that the second scattered light sleeve 300 can be easily plugged onto the light source or onto the optical coupling element or inserted in a light-tight manner into a suitable bore.

The surface quality, the color and the material can be designed in the same way as for the first scattered light sleeve 200 according to 4 . The same advantages apply as with the first scattered light sleeve 200.

The 6 shows a third embodiment of a scattered light sleeve in a sectional view.

A third scattered light sleeve 400 is designed as a cylinder. An outer cylinder 404 and an inner cylinder 403 are each designed to be flat. This is a cheap design. The width of a lateral surface 401 of the third scattered light sleeve 400 is approximately 10% of the diameter. As a result, the third scattered light sleeve 400 points in the same way as the first scattered light sleeve 200 4 a relatively wide first end face 402 and a second end face 405.

A bristle comb 406 is arranged on the first end face 402. The bristle comb 406 allows the gap between the third scattered light sleeve 400 and a filter wheel or a filter slide to be optically sealed without significantly impairing the mobility of the filter wheel or filter slide.

The bristle comb 406 can also be attached to the first scattered light sleeve 4 or according to the second scattered light sleeve 5 be arranged.

The surface quality, the color and the material can be designed in the same way as for the first scattered light sleeve 200 according to 4 . The same advantages apply as with the first scattered light sleeve 200.

Reference symbol list

100

lighting device

101

Light source

102

beam path

110

Filter wheel

111

First lighting filter

112

Second lighting filter

113

axis

114

Arrow

120

Optical coupling element

121

light guide

130

Surgical microscope

131

Illumination light cone

132

Object level

140

First scattered light

141

Second scattered light

142

Third scattered light

143

Fourth scattered light

150

First scattered light sleeve

151

Second diffuser sleeve

160

First gap

162

Second gap

200

First scattered light sleeve

201, 301, 401

Corpus

202, 302, 402

First face

203

inner thread

204

External thread

205, 305, 405

Second front side

303

Inner surface

304

external surface

403

inner cylinder

404

External cylinder

406

bristle comb

300

Second diffuser sleeve

400

Third diffuser sleeve

Claims (15)

Surgical microscope (130) with an illumination device (100, 180) for illuminating an object plane (132), comprising a light source (101) for emitting illumination light in a first wavelength range, illumination optics with an optical coupling element (120), the illumination light being directed along a Beam path (102) is guided from the light source (101) to the optical coupling element (120) and is guided via the illumination optics to the object plane (132), an illumination filter (110) which is in the beam path (102) between the light source (101 ) and the optical coupling element (120) is arranged and has a pass band in a second wavelength range which is suitable as the excitation wavelength range of a fluorescent dye, the beam path (102) being in at least one region between the light source (101) and the optical coupling element (120). is encapsulated in such a way that illumination light emitted by the light source (101) only passes through the illumination filter (110) to the coupling element (120). Surgical microscope Claim 1 , wherein the beam path (102) is designed to be encapsulated in a first area between the illumination filter (110) and the optical coupling element (120). Surgical microscope according to one of the preceding claims, wherein the beam path (102) is designed to be encapsulated in a second region between the light source (101) and the illumination filter (110). Surgical microscope according to one of the preceding claims, wherein the beam path (102) between the light source (101) and the optical coupling element (120) is guided through an encapsulation, the encapsulation having a recess into which the illumination filter (111, 112) can be inserted . Surgical microscope according to one of the preceding claims, wherein the encapsulation is formed by a scattered light sleeve (150, 151). Surgical microscope according to one of the preceding claims, wherein the scattered light sleeve (150, 151) is designed in two parts. Surgical microscope according to one of the preceding claims, wherein a surface of the scattered light sleeve (150, 151, 200) is designed as a thread (203, 204). Surgical microscope according to any preceding claim, wherein the scattered light sleeve (150, 151, 300) is conical. Surgical microscope Claim 5 , wherein a surface of the scattered light sleeve (150, 151, 300) is stepped. Surgical microscope according to one of the preceding claims, wherein an end face (402) of the scattered light sleeve (400) has a bristle comb (406). Surgical microscope according to one of the preceding claims, wherein a surface of the scattered light sleeve (150, 151, 200, 300, 400) is black. Surgical microscope according to one of the preceding claims, wherein a surface of the scattered light sleeve (150, 151, 200, 300, 400) has grooves, grooves or scales, so that a rough surface with an arithmetic mean roughness Ra > 0.1mm is formed. Surgical microscope according to one of the preceding claims, wherein the illumination filter (111, 112) has a pass band in a wavelength range of 400 nm to 435 nm. Surgical microscope according to one of the preceding claims, wherein the illumination filter (111, 112) is arranged on a filter changer (110). Surgical microscope according to one of the preceding claims, wherein the optical coupling element (120) is a light guide.

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