Surgical microscope with OCT system

Abstract

Operating microscope (100) - with a microscope imaging optic (101, 108) comprising a microscope main objective system (101) and a magnification system (108) with variable magnification; - with an observation beam path (109) for examining an object area that penetrates the microscope imaging optics (101, 108); wherein - the microscope imaging optics (101, 108) converts a convergent observation beam path (109) from the object area (114) into a parallel beam path; and - with an OCT system (120, 320) for examining the object area (114), wherein the OCT system (120, 320) provides an OCT scanning beam path (190, 390) which is guided through the microscope main objective system (101), characterized in that - the OCT scanning beam path (190, 390) is guided through the magnification system (108), and that the OCT system has an adjustable collimation optic (130) to adapt an imaging parameter for the OCT scanning beam path (190, 390) to a change in the magnification scale in the observation beam path (109), which is equal to the ratio of the focal length of the microscope imaging optic with microscope main objective system (101) and magnification system (108) and the focal length of the collimation optic (130), wherein the adjustable collimation optic (130) focuses the OCT scanning beam path (190, 390) into a parallel beam (140).

Description

[0001] The invention relates to a surgical microscope with a microscope imaging optics comprising a microscope main objective system and a magnification system with variable magnification, with an observation beam path that passes through the microscope imaging optics, wherein the microscope imaging optics converts a convergent observation beam path from the object area into a parallel beam path, in which an OCT system is provided for examining the object area, according to the preamble of patent claim 1.

[0002] A surgical microscope of the type mentioned above is known from EP 0 815 801 B1. This describes a surgical microscope with a microscope main objective traversed by a stereoscopic observation beam path, to which a zoom system for variable magnification is assigned. The surgical microscope contains an OCT system. This OCT system comprises an assembly for generating an OCT scanning beam path from short-coherent laser radiation, with an analysis unit for evaluating interference signals. This assembly is assigned a device for scanning the OCT scanning beam path. In order to scan a surgical area using the OCT scanning beam path, the scanning device contains two scanning mirrors that can be adjusted around two axes of movement.In the surgical microscope according to EP 0 815 801 B1, the OCT scanning beam path is coupled into the illumination beam path of the surgical microscope via a splitter mirror and is guided with this through the microscope main objective to the object area.

[0003] Optical coherence tomography enables the noninvasive examination and measurement of structures within biological tissue. As an optical imaging technique, optical coherence tomography, combined with a corresponding OCT system, enables the generation of cross-sectional or volume images of biological tissue with micrometer resolution. A corresponding OCT system comprises a source of temporally incoherent and spatially coherent light with a coherence length I. c, which is guided between a sample beam path and a reference beam path. The sample beam path is directed at the tissue under examination. Laser radiation that is reflected back into the sample beam path due to scattering centers in the tissue is superimposed by the OCT system with laser radiation from the reference beam path. This superposition creates an interference signal. From this interference signal, the position of scattering centers for the laser radiation in the tissue under examination can be determined.

[0004] For OCT systems, the construction principle of “time-domain OCT” and “Fourier-domain OCT” is well known.

[0005] The structure of a “time-domain OCT” is described, for example, in US 5 321 501 A using Fig. 1a on column 5, line 40 - column 11, line 10. In such a system, the optical path length of the reference beam is continuously varied using a rapidly moving reference mirror. The light from the sample and reference beams is superimposed on a photodetector. If the optical path lengths of the sample and reference beams match, an interference signal is generated on the photodetector.

[0006] A "Fourier-domain OCT," for example, is described in WO 2006 / 100544 A1. To measure the optical path length of a sample beam path, light from the sample beam path is superimposed on light from a reference beam path. In contrast to a "time-domain OCT," however, to measure the optical path length of the sample beam path, the light from the sample and reference beam paths is not fed directly to a detector, but is first spectrally dispersed using a spectrometer. The resulting spectral intensity of the superimposed signal from the sample and reference beam paths is then detected by a detector. By evaluating the detector signal, the optical path length of the sample beam path can be determined.

[0007] EP 1 220 004 B1 discloses a surgical microscope that allows an observer to examine a surgical area with a stereoscopic observation beam path by looking into an eyepiece. The surgical microscope includes a device for data projection with a display and a beam splitter designed as a splitter cube. This beam splitter is arranged in the main body of the surgical microscope in the parallel observation beam path between the microscope's main objective and the eyepiece. It superimposes a display image projected to infinity by a display optic onto the parallel observation beam path in the surgical microscope.

[0008] DE 695 28 024 T2 discloses an ophthalmic-surgical microscope that is internally combined with an OCT device. The OCT scanning beam path is guided through the microscope's main objective.

[0009] DE 692 27 902 T2 discloses a device for interferometric imaging or measurement of the internal structure of a sample, comprising an interferometer, an optical beam source, a probe module for scanning the sample, a detector, a device for changing the depth of measurement within the sample, and a signal processing device.

[0010] The object of the invention is to provide a compact surgical microscope with variable magnification, in which the acquisition of depth images of an object area is possible with an OCT scanning beam path, the course of which corresponds to the course of the optical observation beam path in the surgical microscope, which produces an enlarged image of the object area for an observer in an eyepiece view, wherein the cross section of the OCT scanning beam path in the object area adapts to the selected magnification.

[0011] This object is achieved by a surgical microscope according to patent claim 1.

[0012] This ensures, especially in the case of an uneven object area, that the optical observation beam path and the OCT scanning beam cover identical zones of the object area. The OCT scanning beam can thus be used to precisely scan the observation image that appears to an observer through the binocular view of a corresponding surgical microscope. Depth sections of the object area can be captured based on the OCT scanning beam.

[0013] In a further development of the invention, a coupling element is provided that couples the OCT scanning beam path into the observation beam path, in order to guide the OCT scanning beam path, superimposed on the observation beam path, through the microscope imaging optics to the object area. The coupling element is preferably designed as a beam splitter, in particular as a plane mirror or beam splitter cube. This ensures that a co-observer always has a clear view of the object area.

[0014] In a further development, an output coupling element is arranged between the microscope imaging optics and the input coupling element in order to output image information from the observation beam path.

[0015] In a further development of the invention, an afocal lens system, preferably designed as a zoom system, is arranged between the coupling element and the microscope's main objective. This makes it possible to vary the lateral resolution of the OCT information obtained with the OCT system in accordance with the image presented to an observer through the eyepiece of the surgical microscope.

[0016] In a further development of the invention, the OCT system comprises a first scanning mirror for scanning the OCT scanning beam path. Preferably, a second scanning mirror is additionally provided, wherein the first scanning mirror can be moved about a first axis of rotation, and the second scanning mirror can be moved about a second axis of rotation. The first and second axes of rotation are laterally offset from each other at a right angle. This allows scanning of an object region according to a vertically extending grid pattern.

[0017] In a further development of the invention, the OCT system comprises a light guide having a light exit section for the OCT scanning beam path, with means for moving the light exit section of the light guide being provided. In this way, an OCT scanning plane can be varied in the object area, and it is possible to adjust the system for different OCT wavelengths for co-observation, given the optical components in the observation beam path designed for visible light.

[0018] In a further development of the invention, an adjustable optical system is provided in the OCT scanning beam path for adjusting a geometric image of an exit end of a light guide into an OCT scanning plane. In this way, the OCT scanning plane of the surgical microscope can be shifted relative to the observation plane of the system's optical observation beam paths, and when adjusting the imaging scale for the microscope imaging optics, it is possible to readjust the imaging scale for the OCT scanning beam such that the imaging scale in the optical observation beam path corresponds to the imaging scale in the OCT scanning beam path. The respective imaging scales can thus preferably be kept identical.

[0019] In a further development of the invention, a drive unit is assigned to the adjustable optical element. In this way, for example, the OCT scanning plane can be varied by a predetermined amount relative to the observation plane of the surgical microscope.

[0020] In a further development of the invention, the OCT system is designed to provide a first OCT scanning light beam with a first wavelength and a second OCT scanning light beam with a second wavelength different from the first wavelength. In this way, the surgical microscope can be optimized for the examination of different tissue structures and body organs of a patient.

[0021] In a further development of the invention, a first and a second OCT system are provided, each providing OCT scanning light beams of different wavelengths. This allows an examination of an object region based on different OCT wavelengths with maximum resolution. In particular, tissue can be examined with OCT scanning light beams at different penetration depths. Furthermore, this makes it possible to design the surgical microscope for various applications.

[0022] In a further development of the invention, a coupling of the microscope imaging optics and an OCT system is provided to adjust a corresponding change in the optical path length in the OCT system when the working distance of the surgical microscope changes. This ensures that an object area sharply imaged by the microscope imaging optics can also be scanned with the OCT system.

[0023] In a further development of the invention, a coupling of the microscope imaging optics and the collimation optics of an OCT system is provided to match the image scale in the optical observation beam path and the image scale in the optical observation beam path and the image scale in the OCT scanning beam path. This ensures that the OCT scanning beam path scans the observation area visible in the optical observation beam paths.

[0024] Advantageous embodiments of the invention are illustrated in the figures and are described below.

[0025] They show: Fig. 1 a first surgical microscope with integrated OCT system; Fig. 2 a section of the microscope main objective in the surgical microscope along the line II - II Fig. 1; Fig. 3 a section of the surgical microscope with a first and a second OCT system; Fig. 4 an intensity distribution of the OCT scanning light beam emerging from the light guide of an OCT system in the surgical microscope; and Fig. 5 an intensity distribution of the OCT scanning light beam in the OCT scanning plane in the object area of ​​the surgical microscope.

[0026] The surgical microscope 100 in Fig. 1 has a microscope main objective system 101, which can be focused by means of an actuator 150, with an optical axis 102 and a correspondingly displaceable focal plane 103. The microscope main objective system 101 comprises partial optics 151, 152, and 153. It is penetrated by stereoscopic observation beam paths of a binocular tube 104 and the illumination beam path 105 of an illumination device 106 with an illumination mirror 107. This illumination mirror is arranged on the side of the microscope main objective system 101 facing away from the object.

[0027] A zoomable magnification system 108 is assigned to the binocular tube 104. The microscope main objective system 101 and the zoomable magnification system 108 form the microscope imaging optics of the surgical microscope 100. The Fig. 1 shows a right observation beam path 109 of the stereoscopic observation beam path in the surgical microscope 100.

[0028] Between the binocular tube 104 and the zoomable magnification system 108, a first splitter cube 112, constructed of rectangular prisms 110, 111, is located in the parallel, right-hand observation beam path 109. A splitter cube identical to the first splitter cube 112 is arranged at a corresponding position in the parallel, left-hand observation beam path. The first splitter cube 112 and the second splitter cube have a dual function: They act as coupling elements, which display the first display 113 and a Fig. 1 not shown second display into the right observation beam path 109 and the left observation beam path of the surgical microscope.

[0029] The display of the first display 113 and the second display is thus superimposed on the image of the object area 114 in the binocular tube 104. At the same time, the first splitter cube 112 and the second splitter cube act as elements for coupling in an OCT scanning beam path 190 provided by a first OCT system 120.

[0030] The surgical microscope 100 contains a first OCT system 120 for acquiring OCT images. The OCT system comprises a unit 121 for generating and analyzing an OCT scanning beam path 190 exiting a light guide 122. The scanning beam path 190 exiting the light guide 122 is guided to a first scanning mirror 124 and a second scanning mirror 125 of an OCT scanning unit 126. After the OCT scanning unit 126, it passes through an adjustable collimation optics 130 with a lens 131 and a lens 132. The collimation optics 130 has a drive 133 and focuses the scanning beam path 190 into a parallel beam 140.

[0031] Of course, it is also possible to deflect a parallel OCT scanning beam path using the first scanning mirror 124 and the second scanning mirror 125 of the OCT scanning unit 126. This requires suitable collimation optics, such as a converging lens, arranged between the light guide 122 and the OCT scanning unit 126. A collimation optics 130 located on the side of the OCT scanning unit 126 facing away from the light guide is then unnecessary.

[0032] The beam 140 from the OCT scanning unit 126 is guided to the splitter cube 112 in the observation beam path 106. The splitter cube 112 is essentially transparent to the spectral range of observation light visible to humans in this observation beam path. However, it reflects the OCT scanning beam path and superimposes it on the observation beam path 106. It should be noted that the splitter cube 112 could also be designed as a mirror element with a plane plate.

[0033] The light from the OCT scanning beam path 190 is focused by the microscope main objective 101 into an OCT scanning plane 195. The OCT scanning plane 195 is the plane of the geometric image of the exit end of the light guide 122 in the object area, defined by the optical elements in the OCT scanning beam path, including the OCT scanning unit 126, converging lens 130, splitter cube 112, and the microscope main objective 101. This means that the corresponding geometric image of the light guide exit end lies in the OCT scanning plane 195.

[0034] The light scattered back into the OCT scanning beam path returns to unit 121 via the microscope's main objective 101, the zoomable magnification system 108, and the splitter cube 112. There, the OCT scanning light scattered back from the object area 114 interferes with OCT radiation from a reference beam path. The interference signal is detected by a detector and evaluated by a computer unit, which uses this signal to determine an optical path length difference between the scattering centers for OCT light in the object area 114 and the path length of light in the reference branch.

[0035] When the working distance 180 of the surgical microscope 100 is varied by adjusting the microscope's main objective system 101, the optical path length of the scanning beam paths of the relevant OCT systems in the surgical microscope is also changed. The actuator 150 of the focusable microscope's main objective system 101 is therefore electrically connected to the OCT systems in the surgical microscope via a signal line 185. This couples the OCT systems to the microscope's main objective system, allowing the optical path length of the reference beam paths in the OCT systems to be adjusted accordingly, if necessary, in the event of a variation in the surgical microscope's working distance 180 from the object area 114.

[0036] In order to be able to supply image information from the object area 114 to a documentation unit, an output element 141 is located between the zoomable magnification system 108 and the splitter cube 112.

[0037] Fig. 2 is a section along the line II - II of Fig. 1. This figure explains the course of the stereoscopic observation beam paths in the surgical microscope 100 on Fig. 1. The optical axis 102 of the microscope's main objective 101 lies at its center. The right observation beam path 109 and the left observation beam path 110 pass through the microscope's main objective 101 with the illumination beam path 105 deflected by the illumination mirror 107 in separate intersection areas 201, 202, and 203.

[0038] Fig. 3 shows the first OCT system 120 and the second OCT system 320 in the surgical microscope 100 of Fig. 1. Like the first OCT system 120, the second OCT system 320 includes a unit 321 for generating and analyzing an OCT scanning beam path. However, the wavelength range of the OCT scanning beam paths of the two OCT systems 120, 320 differs: The first OCT system is based on OCT scanning radiation with a wavelength of λ1 = 1310 nm. The second OCT system 320 operates with OCT scanning radiation with a wavelength of λ2 = 800 nm. Of course, the OCT systems could also be designed for other operating wavelengths.

[0039] Working wavelengths can be realized particularly in the range 600nm < λ < 1500nm and are advantageous depending on the application.

[0040] The OCT scanning beam path 190 of the first OCT system 120 is coupled into the first splitter cube in the right observation beam path of the surgical microscope 100 via the converging lens 130. The OCT scanning beam path 390 of the second OCT system 320 is superimposed into the second splitter cube in the left observation beam path of the surgical microscope 100 via a second converging lens.

[0041] Like the OCT system 120, the OCT system 320 includes an OCT scanning unit 326 with scanning mirrors 324, 325 and a converging lens 330 that collects the OCT scanning beam path 390 into a parallel beam.

[0042] The first scanning mirror 124, 324 and the second scanning mirror 125, 325 of the OCT systems 120, 320 are arranged so as to be rotatable about two mutually perpendicular axes 305, 306, 307, and 308 by means of actuators 301, 302, 303, and 304. This allows the OCT scanning beam paths 190, 390 to be scanned independently of one another across a plane.

[0043] In order to enable an operator to adjust the OCT scanning planes in relation to the object plane of the optical observation beam paths in the surgical microscope 100 from Fig. 1, an adjustability of the converging lenses 131, 331 and the exit end 133, 333 of the light guides 127, 327 is provided. For this purpose, drive units 371, 372, 373, and 374 are assigned to the converging lenses 131, 331 and the light guides 127, 327. By means of these drive units, the converging lenses 131, 331 and the light guides 127, 327 can be displaced according to the double arrows 374, 375, 376, and 377. In particular, this not only allows the position of the OCT scanning planes to be varied, but also allows an enlargement or reduction of the exit end of the light guides 127, 327 to be set to a desired value.

[0044] Fig. 4 shows the front section 402 of the light guide 127 from Fig. 1. The light guide 127 acts as a single-mode fiber for light of wavelength λ1 = 1310 nm. The diameter d of the fiber core of the light guide 127 satisfies the relationship d2<2.4λ12πNA, where NA is the numerical aperture of the front surface of the light guide. Therefore, the diameter d of the fiber core of the light guide 127 is preferably in the range 5 µm < d < 10 µm. In this parameter range, the light guide 127 guides the light with Gaussian wave modes. The OCT scanning light beam 401 emerges from the light guide 127 with an approximately Gaussian radiation profile characterized by a waist parameter W1 and an aperture parameter θ1, where: θ1=λπW1

[0045] For a fiber core diameter of d1 = 10µm and a wavelength λ1 = 1310nm, the beam divergence is measured at an aperture angle of θ0 ≈ 0.0827 rad.

[0046] The front surface 402 of the light guide 122 is scanned via the scanning mirrors 124 and 125 in the surgical microscope 100 from Fig. 1, the converging lens 130, the splitter mirror 150, the deflection mirror 107 and the microscope main objective system 101 are imaged onto the object area 114 in the OCT scanning plane 195.

[0047] The Fig. Figure 5 shows the intensity distribution of the OCT scanning light beam 401 perpendicular to the OCT scanning plane 501. In the OCT scanning plane 501, the intensity distribution of the OCT scanning radiation has a minimum constriction. Outside the OCT scanning plane, the diameter of the OCT scanning beam path increases. Since the OCT scanning light beam 401 emerges from the light guide 122 from Fig. 4 with an approximately Gaussian radiation profile, the converging lens 130 and the microscope main objective system 101 for the OCT scanning light beam in the area of ​​the OCT scanning plane 160 cause a so-called Gaussian beam 500 of the OCT scanning light beam 401. This Gaussian beam 500 is characterized by the confocal parameter z as a measure of the longitudinal extent of the waist of the Gaussian beam, as well as the waist parameter W as a measure of the diameter of the smallest constriction 502 of the OCT scanning light beam 401, i.e., the diameter of its waist, where: z=2W2πλ1, where λ1 is the wavelength of the OCT scanning light beam. Between the waist parameter W of the Gaussian beam 500 and the waist parameter W1 of the Fig. The following relationship applies to the scanning light beam 401 emerging from the light guide 122, as shown in Figure 4: W=βW1, where β is the magnification or reduction parameter of the above-mentioned geometric image of the exit end of light guide 122 from Fig. 1 in the OCT scanning plane. β is the focal length f1 of the collimation optics 130 Fig. 1 and the focal length f2 of the microscope imaging optics with microscope main objective system 101 and magnification system 108 are linked via the following relationship: f2f1=β

[0048] The adjustable collimation optics of the OCT systems allow the imaging parameter β for the corresponding OCT beam paths to be adjusted to accommodate changes in the image scale of the microscope's imaging optics. For this purpose, the relevant image scales are preferably selected to be the same.

[0049] For a specific scanning pattern of the OCT scanning beam path, this means that it is then automatically adapted to the observation image that an observer sees in the eyepiece view of the surgical microscope 100. Fig. 1 offers, adapts.

[0050] The size of structures that can be resolved with the OCT scanning light beam 401 is determined by its diameter in the OCT scanning plane 160, i.e., by the waist parameter W. For example, if an application requires a lateral resolution of the OCT system in the surgical microscope of approximately 40µm, the cross-section of the OCT scanning light beam 401 on the surface must be approximately 20µm according to the Nyquist theory. For a given wavelength λ for the OCT scanning light beam 123 from Fig. 1 Therefore, for a desired resolution of the OCT system 120, the magnification of the optical image in the OCT beam path and the diameter of the fiber core in the light guide 122 must be selected appropriately.

[0051] The confocal parameter z as a measure of the longitudinal extent of the waist of the Gaussian beam determines the axial depth range from which in the OCT scanning beam path 190 Fig. 1 backscattered light can be detected: The smaller the confocal parameter z, the greater the loss of lateral resolution of the OCT system when an object scanned with OCT scanning radiation is moved away from the OCT scanning plane 160, since the location of scattering centers can only be localized within the "funnel" defined by the waist parameter W and the confocal parameter z.

[0052] Since the axial resolution of an OCT system is determined on the one hand by the coherence length I c of the light of the light source used in the OCT system is limited, and on the other hand the lateral resolution of the OCT system decreases when its depth stroke exceeds the confocal parameter, setting the confocal parameter z to the depth stroke of the OCT system is advantageous.

[0053] For a specific wavelength λ of the OCT scanning light beam 401, the possible lateral resolution of the OCT system is then given by Fig. 1, since the wavelength λ and the Rayleigh parameter z determine the waist parameter W. The optical units in the OCT scanning beam path 190 from Fig. 1 and the dimensions of the fiber core of light guide 122 must then be selected to yield the corresponding waist parameter. The same applies to the optical units in the OCT scanning beam path of the second OCT system 320 in the surgical microscope.

[0054] The surgical microscope 100 from Fig. 1 is designed so that the focal plane 103 of the microscope main objective 101 for the visible spectral range coincides with the OCT scanning planes 195 of the OCT systems in the surgical microscope. Then the Fig. 5 shown waist 502 of the relevant OCT scanning light beam in the focal plane of the surgical microscope.

[0055] As an alternative to this design of the surgical microscope, an offset between the OCT scanning plane and the focal plane of the surgical microscope can also be provided. This offset is preferably no greater than the confocal parameter of the OCT scanning light beam in the area of ​​the OCT scanning plane. This makes it possible, for example, to visualize an object region located directly below the focal plane of the surgical microscope using OCT. However, it can also be useful to provide a defined offset that exceeds the confocal parameter for certain applications, for example, to be able to examine the front of the cornea of ​​a patient's eye with the surgical microscope and simultaneously visualize the back of the cornea of ​​the patient's eye or its lens using the OCT system.

[0056] By moving the OCT scanning plane further from the microscope main objective system 101 by the confocal parameter z Fig.1, the depth stroke for the OCT system in the object area can be maximized.

Claims

[1] Surgical microscope (100) - with a microscope imaging optics (101, 108) comprising a microscope main objective system (101) and a magnification system (108) with variable magnification; - with an observation beam path (109) for examining an object area which passes through the microscope imaging optics (101, 108); wherein - the microscope imaging optics (101, 108) converts a convergent observation beam path (109) from the object area (114) into a parallel beam path; and - with an OCT system (120, 320) for examining the object area (114), wherein the OCT system (120, 320) provides an OCT scanning beam path (190, 390) which is guided through the microscope main objective system (101), characterized by , that - the OCT scanning beam path (190, 390) is guided through the magnification system (108), and in that the OCT system has an adjustable collimation optics (130) in order to adapt an imaging parameter for the OCT scanning beam path (190, 390) equal to the ratio of the focal length of the microscope imaging optics with microscope main objective system (101) and magnification system (108) and the focal length of the collimation optics (130) to a change in an imaging scale in the observation beam path (109), wherein the adjustable collimation optics (130) bundles the OCT scanning beam path (190, 390) into a parallel beam bundle (140). [2] Surgical microscope according to claim 1, characterized bythat a coupling element (112) is provided which couples the OCT scanning beam path (190, 390) into the observation beam path (109, 110) in order to guide it, superimposed on the observation beam path (109), through the microscope imaging optics to the object area (114). [3] Surgical microscope according to claim 2, characterized by that a display (113) is provided and the coupling element (112) for the OCT scanning beam path (190, 390) acts as a coupling element for display information in order to superimpose display information on the observation beam path (109). [4] Surgical microscope according to claim 2 or 3, characterized by that the coupling element (112) is designed as a splitter mirror, in particular as a plane mirror or splitter cube. [5] Surgical microscope according to one of claims 2 to 4, characterized bythat a decoupling element (141) is arranged between the microscope imaging optics (101, 108) and the coupling element (112) in order to couple image information out of the observation beam path (109). [6] Surgical microscope according to one of claims 1 to 5, characterized by that the magnification system of the microscope imaging optics is designed as an afocal lens system (108). [7] Surgical microscope according to claim 6, characterized by that the afocal lens system is designed as a zoom system (108). [8] Surgical microscope according to one of claims 1 to 7, characterized by that the OCT system (120) for scanning the OCT scanning beam path (190) comprises a first scanning mirror (124) which can be moved about a first axis of rotation (306). [9] Surgical microscope according to claim 8, characterized bythat a second scanning mirror (125) is provided which can be moved about a second axis of rotation (306), and wherein the first axis of rotation (306) and the second axis of rotation (305) are laterally offset at a right angle to one another. [10] Surgical microscope according to one of claims 1 to 9, characterized by that the OCT system comprises a light guide (127, 327) having a light exit section (402) for the OCT scanning beam path (190, 390), wherein means (371, 372) are provided for moving the light exit section (402) of the light guide (127, 327). [11] Surgical microscope according to one of claims 1 to 10, characterized by that the adjustable collimation optics (130) has a drive (133). [12] Surgical microscope according to one of claims 1 to 11, characterized bythat the OCT system is designed to provide a first OCT scanning light beam having a first wavelength and to provide a second OCT scanning light beam having a second wavelength different from the first wavelength. [13] Surgical microscope according to one of claims 1 to 12, characterized by that a first OCT system (120) and a second OCT system (320) are provided, which provide OCT scanning light beams (190, 390) of different wavelengths. [14] Surgical microscope according to one of claims 1 to 13, characterized by that a coupling of microscope imaging optics (101, 108) and OCT system (120, 320) is provided in order to adjust a corresponding change in the optical path length of the reference beam path in the OCT system (120, 320) when the working distance (180) of the surgical microscope (100) changes.

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