VISUALIZATION ARRANGEMENT FOR MICROSURGERY

Description

[0001] The present invention relates to a visualization arrangement for microsurgery, for example for an operating microscope, comprising an imaging device for generating an image with polarization contrast, for example a stereoscopic imaging device for generating a stereoscopic image with polarization contrast. The invention further relates to a method for generating an image with polarization contrast, for example a stereoscopic image with polarization contrast, of an object to be imaged by means of a visualization arrangement for microsurgery. The invention also relates to a microscope, for example a operating microscope.

[0002] Operating microscopes are used in various microsurgical disciplines, primarily in neurosurgery, spinal surgery, ENT surgery, and ophthalmology. They are characterized above all by their stereoscopic imaging capabilities, large working distances (200 mm–600 mm), and moderate magnifications (up to approximately 20x). These features allow the use of surgical instruments in the sterile operating field while simultaneously providing a stereoscopic view of the surgical site. In recent years, there has been a shift from analog to digital systems. These digital systems utilize cameras and 3D monitors or other 3D display systems (head-mounted displays (HMDs), digital eyepieces (binocular ocular monitors – Boom)) for image acquisition and display.

[0003] A key driver for the further development of surgical microscopes is the users' desire for tissue differentiation. Depending on the discipline and application, this can include distinguishing between tumor and healthy tissue, differentiating between white and gray brain tissue, improving the visualization of vessels and nerves, visualizing phased objects during cataract surgery (lens, capsular bag, etc.), or visualizing membranes during retinal procedures. Digital surgical microscopes offer significant advantages for improved tissue differentiation because their camera systems are designed for this purpose.

[0004] From a user perspective, particularly in the field of neurosurgery, the following requirements arise for tissue differentiation technology. (i) The differentiation of the various tissue types must be performed in real time using stereoscopic image data, i.e., without any noticeable time delay for the user, e.g., surgeons. For digital systems, this time is in the range of <50 ms. (ii) Tissue differentiation must be performed across the entire surgical site, which typically has a diameter of approximately 10–50 mm. The resolution of the tissue differentiation should correspond to the resolution of the stereoscopic image data (analog or digital), although it may be lower. (iii) The tissue differentiation should be intuitively interpretable for the surgeon, and its applicability should be supported by clinical studies. (iv) The tissue differentiation should be able to be switched on and off as needed.(v) The technology used for tissue differentiation must not significantly increase the cost and, in particular, the size of the operating microscope. (vi) Tissue differentiation should ideally be performed without the use of markers and dyes, as these require lengthy approval processes and are often associated with side effects for patients.

[0005] InA large number of technologies for tissue differentiation are known from the scientific literature. Optical technologies offer many advantages over non-optical methods such as ultrasound due to their ease of integration and non-contact measurement. The most important optical technologies for tissue differentiation include the detection of fluorescence / autofluorescence (continuous and / or time-resolved), laser Doppler and laser speckle imaging, optical coherence tomography (OCT), Raman spectroscopy (coherent or incoherent), narrow-band imaging, and the detection of the effect of biological tissue on the polarization state of light. Despite the large number of scientific publications, only a small number of these technologies have been implemented in products, which is due to the difficulty of meeting the aforementioned requirements.

[0006] In recent years, camera-based fluorescence technologies have become prevalent in surgical microscopes and endoscopes because they best meet the aforementioned requirements. These technologies are currently based on the three approved dyes ICG, NAF, and 5-ALA. They are used to differentiate tumor from non-tumor tissue and to visualize blood flow. These fluorescence technologies with the three approved dyes meet requirements (i)-(v), but not requirement (vi), meaning they can only be used in combination with a drug. Another disadvantage of these fluorescence options is that not all relevant tissue types can be distinguished. Some tumor types do not absorb the dyes mentioned above. Furthermore, in neurosurgery, it is crucial to protect brain function during the procedure.This requires identifying the brain's fiber tracts (white matter) and differentiating them from tumors or the gray matter of the cortex. Currently, none of the aforementioned dyes can achieve this. Therefore, there is a significant need, particularly in neurosurgery, for a technology that can differentiate between tumors, blood vessels, and white and gray matter.

[0007] Of the technologies mentioned above, polarization is advantageous because it requires no dyes or drugs and, due to the underlying physical process, is sensitive to different tissue types. Tumors have a disordered structure at the cellular level, while fiber tracts, in particular, represent highly ordered zones. It is known from the literature that such structures have different effects on the polarization of incident light.

[0008] Other microscopes used to investigate the polarization properties of samples are known from US 2016 / 091702 A1 and from the article by Jaepyeong Cha et al., "Real-time, label-free, intraoperative visualization of peripheral nerves and micro-vasculatures using multimodal optical imaging techniques", Biomedical Optics Express, Vol. 9, No. 3, 1097-1110 (12.02.2018).

[0009] The following section describes in detail the formalism of Stokes vectors and the Müller matrix for the interaction of optical elements and tissue in the surgical field with partially polarized light. The Müller matrix is ​​the 4x4 transformation matrix for the Stokes vector of the illumination light, which, after multiplication, yields the Stokes vector at the detector location. Knowledge of the Müller matrix with its 16 elements therefore contains all the information about how the object reacts to partially polarized light. Numerous polarimeters exist in metrology that measure the complete Müller matrix at a point or over an area (e.g., https: / / mountainphotonics.de / product / axo-axostep / ). A Müller polarimeter consists of the following components: a light source, a PSG (Polarization State Generator), a PSA (Polarization State Analyzer), and a detector (either a point or an area).PSG and PSA can be implemented in different ways, for example, using rotating delay elements or stationary ferroelectric elements. For general technical background, reference is made to the following publications: W. Singer, M. Totzeck, H. Gross, Handbook of Optical Systems, Vol. 2 "Physical Image Formation", Chapter 26.2.9, pp. 475ff in the series "Handbook of Optical Systems", H. Gross (Editor), Wiley VCH [1], H. Engstrom, "Coherency matrix polarization measurements: application to magnetoptic garnet films", Appl. Opt. 30 (1991) 1730-1734 [4], A Pigula, NT Clancy, S Arya, GB Hanna, DS Elson in: Video-rate dual polarization multispectralendoscopic imaging, International Society for Optics and Photonics, pp. 93330N-93330N-93334 (2015) [5] and Wei Sheng et al, "Quantitative Analysis of 4 × 4 Mueller Matrix Transformation Parameters for Biomedical Imaging", Photonics 2019, 6, 34; doi:10.3390 / photonics6010034 [6].

[0010] The following explains how a polarization contrast, particularly for a tissue under investigation, can be determined from a Stokes vector. The Stokes vector is a common method in polarization optics for representing partial polarization states [1]. The Stokes vector consists of four real components, the so-called "Stokes parameters," whose values ​​can be determined by measuring the transmission of light through specific polarizers. S → = S 0 S 1 S 2 S 3 = I 0 P 0 − P 90 P 45 − P 135 P R − P L

[0011] This is I 0 for the total intensity, i.e., the transmission of a neutral element, P 0 for transmission through a linear polarizer at 0°, P 45 for transmission through a linear polarizer at 45°, P 90 for transmission through a linear polarizer at 90°, P 135 for transmission through a linear polarizer at 135°, PRfor transmission through a right-hand circular polarizer and PL for transmission through a left-circular polarizer.

[0012] Thus, the Stokes parameter S 0 represents the intensity of the light. S 1 indicates the strength of the difference between the linearly polarized component in the x-direction and in the y-direction of the light, i.e., the proportion of horizontal and vertical linear polarization. S 2 indicates how strong the difference is between the 45° and 135° linearly polarized components in the light, i.e., the proportion of diagonal linear polarization. S 4 indicates how strong the difference is between the right- and left-circularly polarized components in the light, i.e., the proportion of circular polarization.

[0013] An important characteristic parameter of light in tissue contrast is the degree of polarization. gThis is the proportion of polarized light to the total intensity and is calculated from formula (1) according to: g = S 1 2 + S 2 2 + S 3 2 S 0

[0014] For polarized illumination, the degree of polarization is generally reduced by interaction with tissue, including multiple reflections. Since the structures are often linear (e.g., nerve fiber bundles), the linear degree of polarization is particularly important. g lin relevant g lin = S 1 2 + S 2 2 S 0

[0015] The circular degree of polarization is analogous. g circ g circ = S 3 S 0

[0016] The following explains the principle of measuring the Stokes vector. Although the definition of the Stokes vector involves six different polarizers and a measurement of the total intensity, only four polarizers are sufficient to uniquely measure the Stokes parameters. This is because the sum of any two orthogonal polarization states already represents the total intensity. I 0 = P 0 + P 90 = P 45 + P 135 = P R + P L

[0017] The Stokes vector (1) can therefore also be written as follows S → = S 0 S 1 S 2 S 3 = P 0 + P 90 P 0 − P 90 P 45 − P 0 − P 90 P R − P 0 − P 90 i.e., through polarization measurement of P 0 , P 45 , P 90 and PR The Stokes vector is uniquely defined.

[0018] The following section explains the Müller matrix and its information content, particularly for tissues. The polarization effect of an object, such as tissue, consists of transforming an incident Stokes vector into an excreted one. In the linear domain, this transformation is described by multiplication with a 4x4 matrix, the Müller matrix: S → out = M S → in with the Müller matrix M = M 00 M 01 M 02 M 03 M 10 M 11 M 12 M 13 M 20 M 21 M 22 M 23 M 30 M 31 M 32 M 33

[0019] The individual Müller matrix elements each have a simple meaning. They describe the proportion of excitation from one Stokes parameter by another Stokes parameter. For example, M 12 for the suggestion of S 1 through S 2.

[0020] As described in the literature, e.g. in [2], the decomposition of the Müller matrix into elementary polarization matrices is important for the polarization description of tissue. One such decomposition is, for example, the Lu-Chipman polar decomposition, in which a Müller matrix is ​​represented as the product of a depolarization Müller matrix, a retarder Müller matrix, and a diattenuator Müller matrix: M = M Dia M Ret M Depol with the depolarization Müller matrix M Depol = 1 0 0 0 0 a 0 0 0 0 b 0 0 0 0 c the retarder-Müller matrix M R = M LR M CR = 1 0 → 0 → m L 1 0 → 0 → m R where 0 represents a 3-component 0 vector and m L or m R for the 3x3 submatrices of the linear and circular retardance. The submatrix of the linear retardant depends on two quantities: the magnitude of the retardance and the orientation, i.e., the position of one of the two eigenpolarizations. The circular retardant depends only on the magnitude of the circular retardance. Thus, M r uniquely described by only 3 scalar quantities. According to [2], the retardance values ​​result from δ L = cos − 1 M R 1 1 + M R 2 2 2 + M R 2 1 + M R 1 2 2 and δ C = tan − 1 M R 2 1 − M R 1 2 M R 1 1 + M R 2 2 and the diattenuator-Müller matrix M D = 1 D → D → m D with the diattenuation vector D → = 1 M 00 M 01 M 02 M 03 and the submatrix m D = 1 − D → 2 I + 1 − 1 − D → 2 D → 2 D → D → T where I represents the 3x3 identity matrix.

[0021] Besides this well-known decomposition, the polarimetry literature describes a number of other decompositions of the Müller matrix into a function of elementary matrices [2]. This decomposition provides a physically unambiguous and correct representation of the Müller matrix in terms of depolarization, retardance, and diattenuation. However, for the decomposition to be performed correctly, it is necessary that the entire Müller matrix has been measured. If this is the case, then the Müller matrix decomposition is the preferred method of analysis.

[0022] However, polarizers are generally not perfect and must themselves be described by a Müller matrix. This can be taken into account in the measurement process, as shown in [4] and described below. Even when measuring Stokes vectors, it should be considered that the available components are not ideal from a polarization-optical perspective. However, it can be assumed that they do not depolarize. Their effect on partially polarized light is therefore described by a known, but not necessarily simple, Jones matrix. For example, a polarizer might only result in a polarization degree of 0.9. Instead of including this property in the error budget, it is certainly more sensible to consider it in the evaluation. According to [4], a general method for measuring Stokes vectors (or...Polarization matrices) can be established, which only requires that the Jones matrix of the polarization-modifying components is known, but not that these components have a specific value. The basis of the method is the linearity of the polarization matrix transformation in the Jones matrix. P _ out = L _ P _ in L _ + where Pin and Pout represent the input and output polarization matrices, and L represents the Jones matrix of the measurement system. This relationship is linear in Pin, a property that is also preserved when switching to intensity. I out = Spur L _ P _ in L _ + Four intensity measurements with four different L allow a linear system of equations to be set up and P to be determined. I j = Spur L j ¯ P _ in L _ j + , j = 1 , … , 4 = ∑ k = 1 4 A jk P k where Pk represents the real elements P1 - P4 of the polarization matrix. In matrix notation, the solution is obtained by inverting the coefficient matrix. I → = A _ P → ⇒ P → = A _ − 1 I →

[0023] To determine the coefficients A jk, the equation for I j must be multiplied out. I j = Spur L j ¯ P _ in L _ j + = Spur L xx L xy L yx L yy P 1 P 2 + iP 3 P 2 − iP 3 P 4 L xx * L yx * L xy * L yy * = L xx 2 + L yx 2 P 1 + L xx L xy * + L xy L xy * + L yx L yy * + L yy L yx * P 2 + i L xx L xy * − L xy L xy * + L yx L yy * − L yy L yx * P 3 + L xy 2 + L yy 2 P 4

[0024] This results in the elements of the coefficient matrix being: A j 1 = L xx j 2 + L yx j 2 A j 2 = 2 Re L xx j L xy j * + L yx j L yy j * A j 3 = − 2 Im L xx j L xy j * + L yx j L yy j * A j 4 = L xy j 2 + L yy j 2

[0025] For actual measurement, the four different Jones matrices must be realized using polarization-optical components. Several methods exist for this. A standard procedure is described in [4], employing a linear polarizer at 0°, 45°, and 90°, as well as a λ / 4 plate with the slow axis at 90° followed by a polarizer at 45°. An alternative measurement method uses a rotating λ / 4 plate followed by a polarizer. Of course, other configurations are conceivable. With a "good" measurement method, the accuracy of the measurement no longer depends on how precisely the components adhere to a predetermined value (e.g., retardance, extinction ratio), but only on how accurately this value is known. Another important factor for measurement accuracy is how well the components provide an orthonormal basis for the Jones vectors.The relative error of the Stokes vector components is directly incorporated into the Müller matrix. However, for a given accuracy of the components, the relative error will be larger the smaller the corresponding basis vector realized by the measurement process is (i.e., the sensitivity of the measurement method for a given Stokes vector component).

[0026] Document DE 10 2017 100 904 A1 describes an image conversion module for a microscope, which is designed for polarization measurement using a polarization mask. Surgical microscopes designed for at least partial polarization determination are described in documents US 2016 / 091 702 A1, DE 102 42 983 A1, CN 107490851 A, DE 10 2018 110 806 A1 and WO 2016 170 816 A1, as well as in JAEPYEONG CHA et al: "Real-time, label-free, intraoperative visualization of peripheral nerves and micro-vasculatures using multimodal optical imaging techniques", BIOMEDICAL OPTICS EXPRESS, Vol. 9, No. 3, February 12, 2018 (2018-02-12), pages 1097-1110.

[0027] The greatest challenges for integrating a complete Müller polarimeter into a surgical microscope, or more generally any microscope requiring real-time analysis, are the requirements of (i) real-time capability, (ii) stereoscopy, and (v) small footprint and low cost (so). For this reason, only simple crossed linear polarizers have been implemented in surgical microscopes for illumination and observation (su). Numerous approaches to polarimeters aimed at meeting these requirements have been described in the literature, but so far without success.

[0028] The ZEISS EXTARO surgical microscope (https: / / www.zeiss.de / meditec / produkte / zahnheilkunde / operationsmikroskope / extaro-300.html) uses exclusively linear polarizers. A first polarizer is integrated into the microscope's illumination beam path and can be swiveled in and out. Two further polarizers are integrated into the two stereo beam paths, each perpendicular to the polarizer in the illumination system and also swiveling in and out. These polarizers are used to suppress reflections on the surface of teeth ("NoGlare Mode").

[0029] In the "3x3 Müller Polarimetric Endoscope" of the Figure 8In the publication J. Qi, DS Elson, Mueller polarimetric imaging for surgical and diagnostic application, J. Biophotonics 10, 950-982 (2017) / DOI 10.1002 / jbio.201600152 [2], a linear polarizer is fixed in front of the illumination exit point at the distal end of the endoscope. The endoscope is rotated around the optical axis and fixed in three different positions during the measurement process. This allows three different orientations of linear polarization to be achieved in the illumination. A filter wheel with three different polarizers is mounted in the observation beam path in front of the camera. This endoscope can be used to determine a 3x3 submatrix of the Mueller matrix. The measurement time is 11.6 s. Rotation of the endoscope is difficult to implement in clinical practice.

[0030] In publication [2] an endoscope for measuring the complete Müller matrix with rotating PSG and time-sequential PSA with a measurement duration of 30s is also described (see Figure 10 This endoscope, too, is unsuitable for clinical use or for applications requiring real-time evaluation due to its long measurement time and rotating elements. Publication [2] further describes a stereo endoscope with a linear polarizer that provides illumination and a stereo channel at the distal end. The second stereo channel measures the polarization perpendicular to it (see Figure 11Additionally, the polarization measurements are combined with spectral narrow-band imaging. This endoscope meets the requirements for real-time capability and small footprint / cost; however, it does not generate a stereoscopic image for the user, such as a surgeon. Furthermore, only a very small portion of the Müller matrix is ​​determined (2x2 submatrix), so essential information about the sample properties is not captured.

[0031] The publication Vizet, J., Rehbinder, J., Deby, S. et al., In vivo imaging of uterine cervix with a Mueller polarimetric colposcope, Sci Rep 7, 2471 (2017), https: / / doi.org / 10.1038 / s41598-017-02645-9 [3] describes a "Müller polarimetric colposcope" with PSG and PSA based on ferroelectric modulators. The module is mounted below the colposcope and can be swung in and out. The measurement time is approximately 1.6 s, and the entire 4x4 Müller matrix is ​​measured. In terms of its optical setup, a colposcope is similar to a surgical microscope. In this case, the polarimeter module is mounted below the main objective and has a monoscopic beam path. For this reason, this approach does not achieve real-time capability, stereoscopy, a compact design, or low costs.

[0032] Stereoscopic tissue differentiation in real time (<50ms) and on large observation fields (>1cm diameter) that goes beyond the simple use of crossed polarizers is not yet known.

[0033] Against the background described above, the object of the present invention is to provide an advantageous visualization arrangement for microsurgery and an advantageous method for generating an image with polarization contrast using a visualization arrangement for microsurgery, as well as a microscope, in particular an operating microscope.

[0034] The aforementioned problems are solved by a visualization arrangement for microsurgery according to claims 1 and 9, a method for generating an image with polarization contrast using a visualization arrangement for microsurgery according to claim 10, and a microscope according to claim 15. The dependent claims contain further advantageous embodiments of the invention.

[0035] The visualization arrangement according to the invention for microsurgery, for example for an operating microscope, comprises an imaging device, preferably a stereoscopic imaging device, an illumination device, and a polarization determination device. The polarization determination device comprises at least two video cameras designed to detect light waves of a plurality of wavelengths in the visible wavelength range, i.e., in the wavelength range between 400 nm and 780 nm, and at least one further video camera, preferably two further video cameras, a plurality of polarization filter devices, and an evaluation device. Each of the three video cameras is assigned an individual partial beam path in the beam path. The three video cameras can therefore be arranged side by side in the beam path, or in other words, parallel to each other with respect to the beam path.This does not necessarily mean a spatially or geometrically parallel arrangement or a spatial arrangement next to each other, but rather an arrangement that allows the separate detection of light waves from different partial beam paths of a beam path by the individual video cameras.

[0036] The at least two video cameras used to capture multicolored visible light are, for example, RGB cameras. The at least one additional video camera could, for example, be a fluorescent camera.

[0037] At least one polarization filter device is arranged in the beam path upstream of at least three of the at least three video cameras, for example, upstream of each of the three video cameras mentioned. Optionally, at least one polarization filter device can be arranged in the beam path downstream of the illumination device and upstream of an object space area, for example, an object to be imaged or an object plane. The polarization filter devices are set or adjustable such that the polarization effects of the polarization filters arranged in the beam path upstream of the at least one additional video camera mentioned and at least one of the video cameras mentioned, which are designed to capture light waves of a plurality of wavelengths in the visible wavelength range, differ from one another. Thus, at least two, preferably three, polarization filter devices upstream of the video cameras are set or adjustable differently from one another.For example, the polarization filter devices can also be set or adjusted so that the three polarization filters arranged in the beam path in front of the three video cameras mentioned differ from each other in their polarization effect, i.e., so that each of the three video cameras mentioned receives light with respect to polarization that differs from the other two video cameras at the same time.

[0038] In this context, an object to be depicted also includes a subject or a part of a subject, for example human, animal or plant tissue.

[0039] The evaluation unit is designed to generate images, for example two- or three-dimensional images, with polarization contrast from the images captured by the video cameras and to display them using the imaging device, preferably stereoscopically. The generated images with polarization contrast can be superimposed into the beam path of the imaging device. They can be partially overlaid transparently on an image without polarization contrast. Thus, the generated images with polarization contrast can be shown or hidden. The polarization filter devices can also be switched on and off.

[0040] In an advantageous embodiment, the evaluation device is designed to display the images generated with polarization contrast by the imaging device overlaid with white-light images captured by at least two video cameras designed to detect light waves of a plurality of wavelengths in the visible range. The at least two video cameras can be the two mentioned above. However, there can also be more than three video cameras. In particular, at least one of the video cameras for detecting multicolored visible light can be positioned without a polarization filter device, at least sequentially. In this way, high-resolution multicolored images can be generated with at least one of the video cameras for detecting multicolored visible light, and the generated images with polarization contrast can be superimposed on these.For example, the polarization filter device in front of at least one of the video cameras for capturing multicolored visible light can be switched such that images with and without a polarization filter are captured alternately – preferably at intervals of less than 100 ms, particularly less than 40 ms. This allows high-resolution images of the object to be captured with and without polarization contrast using the same video camera. Alternatively, at least one additional video camera can be provided, with at least one video camera designed to capture a multicolored image of the object without polarization contrast. An image with polarization contrast can be superimposed on the captured image.

[0041] White light can be understood, for example, as light with a broadband color spectrum. The wavelengths can essentially lie within the visible range. The distribution of wavelengths is usually continuous. Due to the broadband color spectrum of a "white light source," humans perceive a white color. This refers to the color impression created in the eye. It is therefore a physiological effect, not a physical one. This means that a white color impression can be based on different spectra, all of which are limited to the visible range.

[0042] The visualization arrangement can be designed as a visualization arrangement for a microsurgical device, for example, as a visualization arrangement for an operating microscope, in particular an operating microscope designed for neurosurgical operations. Preferably, the visualization arrangement is designed to be completely digital.

[0043] If the visualization arrangement is configured as a component of a microscope, the microscope can be a fully digital microscope, particularly a surgical microscope. The visualization arrangement can be designed to stereoscopically record and display white-light video data and / or fluorescence video data in real time, especially overlaid with polarization contrast images in real time. If used as a component of a surgical microscope, the microscope can preferably be designed for neurosurgical procedures. It can have an object surface or plane with an area or diameter between 10 mm and 50 mm.Preferably, the resolution of the generated images with polarization contrast is lower than the resolution of a (stereoscopic) image without polarization contrast displayed by the (stereoscopic) imaging device, or the resolutions are equal. For example, the resolutions may differ by less than 10 percent.

[0044] In another variant, the specific meaning of the determined polarization contrast for the particular application can be stored and switched on and off via a display. For example, in the case of a neurosurgical application, the type of tissue imaged with polarization resolution, or tissue characteristics derivable from the polarization-resolved image, can be displayed. For this purpose, the complete Müller matrix can be determined for individual tissue types in clinical studies. From an analysis of the Müller matrix, the clinically or generally relevant elements for the respective application can be derived for individual tissue types. Then, within the context of the visualization setup, e.g., using a microscope, only the relevant elements of the Müller matrix can be determined, or the Stokes vector components required for this purpose can be measured.The visualization setup can be designed to determine a specific reduced Müller matrix.

[0045] The visualization arrangement according to the invention has the advantage of offering integrated polarization measurement technology, which meets the requirements of real-time capability, small installation space, low cost, and optional stereoscopy. In a variant as a visualization arrangement for a surgical microscope, the present invention enables improved tissue differentiation, particularly in the field of neurosurgery. Using the visualization arrangement according to the invention, data can be acquired simultaneously, allowing the determination of Stokes vectors and the complete Müller matrix, or of Müller matrix elements or coefficients that are essential for the respective application.

[0046] In an advantageous embodiment, at least one of the polarization filter devices, for example, the at least three, e.g., four, polarization filter devices arranged in front of the three, e.g., four, video cameras, preferably all of the polarization filter devices mentioned above, comprises a plurality of different polarizers, for example, at least four different polarizers. At least one of the polarization filter devices can include a filter wheel for switching between a plurality of different polarizers. In this way, one polarizer from the plurality of polarizers can be introduced into the beam path at any given time. At least one of the polarization filter devices can, for example, comprise at least three, in particular four, linear polarizers and optionally at least one circular polarizer.For this purpose, at least one of the polarization filter devices may include one or more delay elements and / or at least variable retarders and / or ferroelectric elements, etc.

[0047] In an advantageous configuration, i.e., with a suitable selection of the polarizers of the individual polarization filter devices placed in the beam path, at least three of the four polarizers arranged in front of the video cameras, preferably all four, differ from each other with respect to their polarization effect in a variant with four cameras. For example, three of the polarizers can be linear polarizers, for example, a selection from those listed in the Figure 3The polarizers P0, P45, P90, and P135 shown can be circular polarizers, or three or four of the polarizers can be linear polarizers. Identical filters with respect to their polarizing effect can be arranged or set in front of video cameras designed to capture light waves of a plurality of wavelengths in the visible wavelength range. Preferably, their polarizing effect is orthogonal to the polarizer optionally arranged after the illumination device and in front of the object to be imaged.

[0048] In an advantageous embodiment, at least one, for example two, of the at least one further video camera is designed to detect monochromatic light, i.e., light of a defined wavelength or a defined wavelength range, in particular fluorescent light. The detectable wavelength range can also extend beyond the visible wavelength range.

[0049] In another variant, at least one of the aforementioned video cameras, e.g., the three mentioned, can be configured as a polarization camera. The polarization camera can, for example, have four linear polarizers at the pixel level. Alternatively, the polarization camera can have at least one circular polarizer, for example, instead of one of the four linear polarizers, i.e., three linear polarizers and one circular polarizer at the pixel level. A polarization filter device positioned in front of a video camera not configured as a polarization camera—that is, in front of a video camera designed to capture light waves of multiple wavelengths in the visible spectrum—can include a circular polarizer or be configured as a circular polarizer. This can be implemented as a combination of a linear polarizer and a retarder, e.g., a lambda / 4 element below zero degrees.

[0050] The evaluation device is advantageously designed to determine, in particular a finite set, of Müller matrix coefficients using the images captured by the video cameras and to determine, for example calculate, a polarization contrast derived therefrom.

[0051] In a particularly advantageous embodiment, the polarization filter device, optionally arranged in the beam path after the illumination device and before the object space, is designed to simultaneously polarize at least two defined, differing wavelengths, for example, two defined, differing wavelength ranges, differently. This enables the simultaneous acquisition of a larger number of data points, from which, in turn, a larger number of Müller matrix coefficients can be determined. This allows for the determination of stronger polarization contrasts and thus the generation of high-quality images with polarization contrast. Furthermore, the simultaneously available detection channels (e.g.,The number of camera sensors (in RGB cameras), and optionally spectrally coded detection channels, can be used for different polarization information of an object under investigation. The polarizations and spectra can therefore be designed so that multiple detection channels, e.g., each detection channel, provide different information, e.g., tissue information.

[0052] At least one of the polarization filter devices can comprise a color filter or wavelength filter and / or a wavelength-selective or wavelength-specific polarizer. This allows, in particular, the previously described configuration to be implemented. The respective polarization filter device can, for example, comprise a notch filter, especially a polarizing notch filter, and / or a bandpass filter, especially a polarizing bandpass filter.

[0053] In general, the polarization filter devices mentioned can include filters for fluorescence and / or polarization, in particular wavelength-specific polarization. For example, a first polarization state can be set or adjustable for at least one first wavelength or wavelength range, and a second polarization state can be set or adjustable for at least one second wavelength or wavelength range.

[0054] The lighting device can be designed to emit bichromatic or polychromatic light. Preferably, the lighting device is designed to emit polychromatic light, and the polarizing filter device arranged in the beam path after the lighting device and before the object space comprises at least one, for example two, notch filter, preferably a polarizing notch filter, and / or at least one, for example two, bandpass filter, preferably a polarizing bandpass filter.

[0055] Furthermore, the visualization setup can include at least one beam splitter, for example a dichroic beam splitter. This can be positioned in the beam path between the object space area and the video cameras.

[0056] At least one of the video cameras designed to capture or receive light waves of a plurality of wavelengths in the visible wavelength range can be designed as a 3-chip camera or as a 1-chip camera.

[0057] An alternative visualization arrangement according to the invention for microsurgery, compared to the visualization arrangement described above, comprises an imaging device, e.g., a stereoscopic imaging device, an illumination device, and a polarization determination device. The polarization determination device comprises two polarization cameras, each of which is assigned an individual partial beam path in the beam path, and an evaluation device. The evaluation device is designed to generate images with polarization contrast using the images captured by the polarization cameras and to display them by means of the imaging device, preferably stereoscopically. The alternative visualization arrangement according to the invention offers a solution equivalent to the visualization arrangement described above.Both variants utilize the same technical effects to generate images with polarization contrast and have the same features and advantages described in detail above. In particular, the alternative visualization arrangement according to the invention can have the features and properties that are optional in connection with the first visualization arrangement described above.

[0058] The evaluation unit is designed to display the generated images with polarization contrast superimposed on white light images, the white light images being captured by the two polarization cameras. The display is then achieved using the imaging device.

[0059] The inventive method for generating an image with polarization contrast, e.g., a stereoscopic image with polarization contrast, of an object using a previously described visualization arrangement according to the invention for microsurgery, in particular for an operating microscope, comprises the following steps: Light waves, in particular in the visible wavelength range and optionally beyond, are shone onto the object by means of the illumination device. Light waves emitted by the object after an interaction with the shone-on light waves are detected or received by means of the at least two polarization cameras or at least three video cameras.An image with polarization contrast, preferably a stereoscopic image with polarization contrast, is produced based on a generated polarization state of the incident light waves and / or an analyzed polarization state of the detected or received light waves. The method according to the invention has the features and advantages of the visualization arrangement already described.

[0060] In an advantageous embodiment, light waves of a defined polarization state are illuminated by means of the illumination device and a polarization filter device arranged in the beam path downstream of the illumination device and upstream of the object. The polarization state of the received light waves can be analyzed using the aforementioned video cameras and the polarization filter devices arranged upstream of them in the beam path. Using the evaluation device, an image, e.g., a stereoscopic image, with polarization contrast can be generated based on an analyzed polarization state of the captured or received light waves. A set of Müller matrix coefficients is determined from the images captured by the video cameras and / or the polarization cameras, and a polarization contrast derived therefrom is determined, in particular calculated.

[0061] The image, e.g., a stereoscopic image, with polarization contrast is preferably generated within a time interval of less than 50 ms. The resolution of the generated image, e.g., the stereoscopic image, with polarization contrast preferably deviates by less than 10 percent from the resolution of a corresponding image, e.g., a stereoscopic image, without polarization contrast. Particularly preferably, the image, e.g., the stereoscopic image, with polarization contrast is generated within a time interval of less than 50 ms and displayed superimposed on a multicolored image, e.g., a stereoscopic image.

[0062] Within the framework of the inventive method, photogrammetry can be applied to the video signals to identify corresponding pixels, e.g., in the stereo channels, for polarimetric evaluation. A numerical value reflecting a polarization property can be calculated pixel by pixel. From this, a color value reflecting the polarization property can be derived pixel by pixel. A stereoscopic representation of the polarization property, either alone or superimposed on the white light image, can be performed in real time.

[0063] The microscope according to the invention, which may be a surgical microscope – for example, a neurosurgical operating microscope – comprises a visualization arrangement according to the invention as described above and / or is designed to carry out a previously described method according to the invention. It has the features and advantages already mentioned above. The microscope according to the invention is preferably stereoscopic and / or partially or completely digital.

[0064] The microscope, in particular the operating microscope, can include optics with a variable focal length, i.e., optics with variable focus (varioscope), and / or at least one objective lens which is arranged in the beam path in front of at least one of the video cameras, and / or at least one zoom lens and / or a surrounding camera, i.e., a video camera for capturing a spatial area around an object area to be imaged microscopically.

[0065] The invention is explained in more detail below with reference to exemplary embodiments and the accompanying figures. Although the invention is illustrated and described in detail by the preferred embodiments, the invention is not limited by the disclosed examples and other variations can be derived from them by a person skilled in the art without departing from the scope of protection of the invention.

[0066] The figures are not necessarily detailed or to scale and may be enlarged or reduced to provide a better overview. Therefore, the functional details disclosed here are not to be understood as limiting, but merely as an illustrative basis to guide those skilled in this field of technology in using the present invention in a variety of ways.

[0067] The expression "and / or" used here, when used in a series of two or more elements, means that each of the listed elements can be used alone, or any combination of two or more of the listed elements can be used. For example, when describing a composition containing the components A, B, and / or C, the composition can contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination. Fig. 1 schematically shows an operating microscope according to the invention with a visualization arrangement according to the invention in the form of a block diagram. Fig. 2 schematically shows, in the form of a block diagram, the polarization-optical mode of operation of a visualization arrangement according to the invention. Fig. 3 schematically shows exemplary polarization filters. Fig. 4 schematically shows, in the form of a block diagram, the polarization-optical mode of operation of an exemplary variant of a visualization arrangement according to the invention. Fig. 5 schematically shows, in the form of a block diagram, the polarization-optical mode of operation of an exemplary variant of a visualization arrangement according to the invention. Fig. 6 schematically shows, in the form of a block diagram, the polarization-optical mode of operation of an exemplary variant of a visualization arrangement according to the invention.Figure 7 schematically shows, in the form of a block diagram, the polarization-optical mode of operation of an exemplary variant of a visualization arrangement according to the invention. Figure 8 schematically shows, in the form of a block diagram, the polarization-optical mode of operation of an exemplary variant of a visualization arrangement according to the invention. Figure 9 schematically shows the principle of a polarization camera. Figure 10 schematically shows two diagrams representing possible illuminations of the object area. Figure 11 schematically shows a diagram illustrating the implementation of a [missing information]. Figure 10 The illumination shown below is illustrated using polarizing notch filters. Fig. 12 schematically shows a realization of the illumination shown in the Figure 11The variant shown uses polarizing bandpass filters. Fig. 13 schematically shows, in the form of a block diagram, the polarization-optical mode of operation of an exemplary variant of a visualization arrangement according to the invention using two different wavelengths. Fig. 14 schematically shows, in the form of a block diagram, the polarization-optical mode of operation of an exemplary variant of a visualization arrangement according to the invention using two different wavelengths and two polarization cameras. Fig. 15 schematically shows, in the form of a block diagram, the polarization-optical mode of operation of an exemplary variant of a visualization arrangement according to the invention using two different wavelengths. Fig. 16 schematically shows spectral resolutions of a prism and a filter. Fig. 17 schematically shows a method according to the invention in the form of a flowchart.

[0068] The Figure 1Figure 1 schematically shows an operating microscope 1 according to the invention in the form of a block diagram. The operating microscope 1 can be designed, for example, for use in neurosurgery and spinal surgery. The operating microscope 1 comprises a visualization arrangement with an illumination device 4, an object plane or object space 5 in which, for example, an object to be magnified can be arranged, a stereoscopic imaging device, and a polarization determination device. The illumination device 4 is designed to illuminate the object space 5, i.e., to shine light waves onto an object. The beam path is indicated by arrows with the reference numeral 6.

[0069] The microscope 1 is preferably designed as a fully digital microscope. It is preferably designed to stereoscopically record and display both white-light video data and fluorescence video data in real time. This is achieved by using two video cameras 2, which are designed to capture light waves of a plurality of wavelengths in the visible wavelength range (VIS cameras, e.g., RGB cameras), and at least one further video camera 3, preferably two further video cameras 3 as shown, which are designed as monochrome cameras to increase sensitivity and are designed to capture fluorescent light (fluorescence cameras). The two VIS cameras 2 are preferably either 3-chip or 1-chip cameras. The fluorescence cameras 3 can also be designed to capture light waves beyond the visible range.

[0070] Additionally, the microscope 1 includes a variable focal length optic (varioscope) 7, two zoom optics 8, iris elements 19, and two video lenses 9. The variable focal length optic (varioscope) 7, the two zoom optics 8, and the two video lenses 9 are arranged in the beam path 6 between the object space 5 or an object located in the object space and the aforementioned video cameras 2, 3. A laser autofocus device 10 is integrated into the Figure 1The optical system is arranged in beam path 6 between the variable focal length optics 7 and the zoom optics 8. Between the video lenses 9 and the aforementioned video cameras 2 and 3, beam splitters 12 are arranged in beam path 6. These beam splitters 12 create individual partial beam paths, so that each of the aforementioned video cameras 2 and 3 in beam path 6 is assigned its own individual partial beam path. The microscope 1 also optionally includes a peripheral camera 11, which can capture a large field around the object area viewed by the microscope, e.g., the magnified surgical site, and which can be used for tool tracking and navigation functions.

[0071] The polarization determination arrangement comprises, in addition to the four video cameras 2, 3 mentioned above, a plurality of polarization filter devices 20-24 and an evaluation device (not shown). One polarization filter device 21-24 is arranged in the beam path 6 upstream of each of the four video cameras 2, 3, and one polarization filter device 20 is arranged in the beam path 6 downstream of the illumination device 4 and upstream of the object space 5. The polarization filter devices 21-24 are set or adjustable such that the polarization effect of the polarization filters 21-24 arranged in the beam path 6 upstream of at least one, preferably both, of the two additional video cameras 3 and at least one, in particular both, of the video cameras 2 designed to detect light waves of a plurality of wavelengths in the visible wavelength range differs from one another.In other words, the polarization setting of at least one polarization device 22, 23, which is arranged in front of one of the video cameras 2 designed to detect visible light (VIS camera), differs in operation from the polarization setting of at least one polarization device 21, 24, which is arranged in front of one of the other video cameras 3 (e.g. fluorescence camera).

[0072] The polarization determination setup enables the analysis of the polarization state of the light emitted by an object 5, whereby multiple polarization measurements can be performed simultaneously using the multiple video cameras 2, 3. This allows for the acquisition and evaluation of the required data in real time. To generate a polarization-resolved, e.g., three-dimensional stereoscopic, overall image of an object, for example, differently configured polarization filter wheels or various polarizers 20-24 can be positioned in front of the four cameras 2, 3 and in the beam path 6 after the illumination device 4. These are equipped, on the one hand, with suitable excitation and observation filters for the aforementioned fluorescence options, and on the other hand, they contain polarizers suitable for polarimetry.

[0073] In the case of using an alternative visualization arrangement according to the invention as described above, the video cameras 2 are designed as polarization cameras. In this variant, the additional video cameras 3, the beam splitters 12 and the polarization filter arrangements 20 to 24 can be omitted.

[0074] Simplified diagrams are used below for the polarization-optical description of the system. Figure 2Figure 1 schematically illustrates, in the form of a block diagram, the polarization-optical mode of operation of a visualization arrangement according to the invention. An evaluation unit 13 analyzes and evaluates the image data acquired by the four cameras 2, 3 and synthesizes this data into a three-dimensional overall image with polarization contrast. The generated overall image is visualized or displayed to a user by means of a stereoscopic imaging device 14. The data transmission between the video cameras 2, 3 and the evaluation unit 13, as well as between the evaluation unit 13 and the stereoscopic imaging device 14, is identified by reference numeral 15. During the analysis and evaluation of the acquired data, Stokes vectors or parts thereof are preferably determined, and a plurality, preferably more than four, of Müller matrix coefficients are determined, in particular calculated.The polarization contrast is determined using the calculated Müller matrix coefficients.

[0075] The Figure 3 This schematically shows exemplary polarization filters and their designations. The polarizing effect of the filters is indicated by the direction of the transmitted polarization. The polarizers 20-24 each comprise a number, preferably a plurality, of different polarizers, for example one or more of those described in the Figure 3 The polarizers shown. Preferably, the polarization is individually adjustable at each of the polarization filter devices.

[0076] To measure the complete Stokes vector, four different polarizers are required at filter positions 21-24. An example of this is shown in the Figure 4shown, whereby the polarizers can also be distributed differently across the four filter positions 21-24. In surgical microscopy, the linear polarization component may be of primary interest, so the circular polarizer can potentially be omitted. This could then be, as in the Figure 5 shown, for example, to be replaced by a 135° filter in order to obtain redundancy in determining the total intensity.

[0077] In another, in the Figure 6 In the variant shown, the same polarization filters are arranged or set in front of the two video cameras for visible light 2 (VIS cameras or RGB cameras) in order not to interfere with the stereo image. It is advantageous if the illumination polarization 4, 20 is set orthogonal to the polarization of the filter 22, 23 in front of the two video cameras for visible light 2. This is shown in the Figure 7shown, whereby the Stokes vector components S0, S1 and S2 can be measured with undisturbed stereo imaging.

[0078] The measurement of Stokes parameters in a digital surgical microscope can also be performed using one or more polarization cameras, which realize the four measurements necessary for determining the Stokes vector by means of small polarization filters on the camera pixels. Then at least one of the four video cameras 2, 3 is a polarization camera 17. Preferably, one of the other video cameras 3 is a polarization camera, as for example in the Figure 8 The polarization filter arrangement 24 is shown. Figure 8 This is optional. The principle of a polarization camera is described in the Figure 9 shown. Four adjacent pixels 16 in a plane are each equipped with polarizers that differ from each other.

[0079] Available polarization cameras, e.g., from the manufacturer Sony, have 5 megapixels and achieve 23 frames per second. This means a time delay of 43 ms between two images, which is just within the target specification of 50 ms. The four polarizers correspond to equation (1). P 0 , P 45 , P 90, and P 135. This allows the first 3 Stokes parameters ( S 0 , S 1 , S 2) measured, but not the 4th component S3. For imaging tissue in reflection, this can be an acceptable limitation because the structural features are essentially linear and should therefore primarily influence the linear polarization components. A potential problem arises when imaging deep tissues, as fiber layers lie obliquely oriented relative to each other. This would correspond to a combination of differently oriented linear retardation plates, which can lead to rotation and thus also to circular birefringence. To measure all Stokes parameters, for example, the 135° polarizer or the 45° polarizer can be used in the Figure 5 It can also be superimposed with a lambda / 4 retarder below 0°. Together, the two then form a circular polarizer.

[0080] With an incomplete measurement of the Müller matrix, the decomposition described above by Chipman and Lu is not possible. Furthermore, the primary goal of an operating microscope with polarization contrast is not to measure the Müller matrix completely and precisely, but rather to provide the user, for example, the surgeon, with good tissue contrast. Numerous analyses have been conducted on this topic in the past.

[0081] One variant is described in [6]. There, based on simulations of the polarization effect of isotropic and anisotropic tissue, a series of parameters were defined that result directly from the Müller matrix coefficients. In this case, it is therefore sufficient to measure a finite set of Müller matrix coefficients and calculate a derived contrast from them. Examples from [6] are summarized in the following table: contrast calculation Linear depolarization b = M 11 + M 22 M 00 (17) Anisotropic scattering t 1 = M 11 − M 22 2 + M 12 + M 21 2 M 00 (18) Anisotropic scattering t 2 = M 10 2 + M 20 2 M 00 (19) Birefringence t 3 = M 31 2 + M 32 2 M 00 (20)

[0082] These are just examples. There are other useful combinations of Müller matrix elements that can be used as image contrast in surgical microscopy.

[0083] A linear anisotropic medium investigated in [6], which is comparable in shape to biological fibers, shows the following symmetry of the Müller matrix: M = I 0 A B 0 A C D 0 B D E 0 0 0 0 0

[0084] Only a 3x3 subset is non-zero and also symmetrical. Therefore, there are only 6 independent components. I 0 ,A,B,C,D,E, which ones need to be determined.

[0085] To measure parts of the Müller matrix, it is necessary to illuminate not just one, but several polarization states. An obvious solution would be to make filter 20 rotatable or to supplement it with a ferroelectric liquid crystal filter. However, this would only allow illumination with multiple polarization states in a time-sequential manner. Since the polarized image already only just meets the target specification, time-sequential polarized illumination would likely significantly exceed the requirement of a maximum 50 ms time delay for tissue contrast. If time cannot be used as a differentiating parameter for illumination polarization, the wavelength of the illumination light can be used within the scope of the present invention. Simultaneous illumination with two polarization states becomes possible if these are located at different points in the spectrum.The corresponding images can then be reconstructed using a spectral filter. This means the illumination must be polarized differently in two narrow spectral bands. If a "normal color impression" is still desired, unpolarized light or light in any polarization state should be present around it (see...). Figure 3 Alternatively, bichromatic illumination is an option. This can be achieved, for example, with two notch filters, as shown in Figure 10 shown.

[0086] The Figure 10 schematically shows two diagrams that depict possible lighting conditions for the object space. InBoth diagrams show the intensity I of the incident light as a function of the wavelength λ. The upper diagram shows bichromatic illumination with a first wavelength range 31 and a second wavelength range 32. The two wavelength ranges 31 and 32 are polarized differently from each other. The lower diagram shows polychromatic illumination, where the two wavelength ranges 31 and 32 are polarized differently from each other, and the remaining spectral range 33 is unpolarized. This can be achieved, for example, by two notch filters, as shown in the Figure 11 shown. Two narrowband polarized spectral components 31 and 32 are realized by transmitting unpolarized light through two narrowband polarizing notch filters. To realize the [unclear] in the Figure 11 The concept shown allows, for example, the use of polarizing bandpass filters in reflection, as in the Figure 12 shown. Figure 12 The operating principle of a polarizing bandpass filter 34 from Semrock (https: / / www.semrock.com / a-new-class-of-polarization-optics-designed-specifically-for-lasers.aspx) is illustrated. On the left, the beam path for three different wavelengths λ₁, λ₂, and λ₃, as well as the respective linear polarizations s and p, are shown. Here, s and p denote mutually orthogonal linear polarizations. On the right, in the Figure 12 A diagram is shown which depicts the transmission T through the filter 34 as a function of the wavelength λ and the polarization s and p.

[0087] Depending on which polarization states are irradiated and which are measured, different Müller matrix components of the

[0088] Measurement accessible, with which in Figure 13 shown configuration e.g. M 00 , M 01 , M 10 , M 11. In the in the Figure 13In the variant shown, two mutually perpendicularly polarized wavelengths or wavelength ranges λ 1 and λ 2 are used as irradiation, whereby the individual polarized wavelengths are analyzed by different cameras, in the variant shown the wavelength λ 1 by a first video camera for visible light (RGB camera) 2 and a first further video camera 3 and the wavelength λ 2 by a second video camera for visible light (RGB camera) 2 and a second further video camera 3.

[0089] Of course, other configurations are conceivable; for example, the RGB cameras 2 can be replaced by monochrome cameras 3, or vice versa. However, without polarization cameras, due to the spectral division, only 2 Stokes vector components, not 3 or 4, can be measured. Figure 13 The variants shown are S0 and S1. However, these could also be S0 and S2, which are the Müller matrix components. M 00 ,M 02 ,M 20, M 22 makes accessible.

[0090] In the Figure 14 In the variant shown, half the Müller matrix, i.e., 8 Müller matrix elements, can be measured using 2 polarization cameras 17 as additional cameras 3 and two input polarizations. Here, the filter 20 (not shown) is a polarizing notch filter that, in an unpolarized illumination spectrum, only measures the two wavelengths λ 1 and λ2 is polarized. The rest of the illumination spectrum is unpolarized. Filter 21 is a filter for wavelength λ1 and optionally polarization 1, and filter 24 is a bandpass filter for wavelength λ2 and optionally polarization 2. Alternatively, the neutral beam splitter could also be configured as a dichroic beam splitter, e.g., one for a wavelength with a first polarization and a second for a wavelength with a second polarization. This would be more efficient in terms of lighting budget but would reduce flexibility. The advantage of this method is that polarization becomes an additional option that does not interfere with the standard imaging.

[0091] Figure 15 Figure 1 shows another embodiment for spectral coding in which the spectral properties of the RGB channels of the two color video cameras 2 are advantageously used. How to Figure 14 It is also described in the Figure 15The undrawn filter 1 is a polarizing notch filter designed to illuminate with four different wavelengths with defined, predetermined polarizations. The polarizations for the different wavelengths can be different or partially identical. Either single-chip or triple-chip cameras can be used as video cameras 2 (RGB cameras). In the case of single-chip cameras, a Bayer filter separates the single sensor into three spectrally distinct pixel arrays, while in triple-chip cameras, the beam splitter prism enables the spectral separation across the three sensors. The selection of the wavelengths of filter 20 is carried out in Figure 15 so that the RGB sensors detect the wavelengths separately and there is no crosstalk between the different wavelengths. This can be achieved, for example, by illumination with wavelengths of 400 nm, 540 nm, and 680 nm, as are the typical spectral sensitivities of RGB sensors and Bayer filters in [reference to relevant source]. Figure 16show. In the Figure 16The relative spectral sensitivity as a function of the wavelength of a beam splitter prism (top) and a Bayer filter (bottom) is shown. The fourth wavelength of the illumination filter 20 is chosen such that the two monochrome cameras 3 can detect signals spectrally separate from the RGB cameras 2. This can be achieved, for example, by illuminating with a wavelength in the infrared range at which the RGB cameras 2 are no longer sensitive (e.g., at 800 nm). Of course, it is also conceivable that the wavelengths are chosen differently and that interfering wavelengths are removed in front of the sensors by suitable notch filters. The filters 22 and 23 in front of the RGB cameras 2 are thus ideally designed as multibandpass filters for the wavelengths 400 nm, 540 nm, and 680 nm. At the same time, the filters 22 and 23 can be designed differently with respect to their polarization properties.Filters 21 and 24 in front of the other video cameras (monochrome cameras) 3 are designed as bandpass filters for the wavelength 800nm, with optionally different polarization properties with respect to filters 21 and 24.

[0092] The exemplary embodiment of the Figure 15 This describes a special case and can be generalized as follows: In the first step, the number N of detection channels present in the system is determined. In the Figure 1 In the example shown, there are 8 channels, with the two additional video cameras (monochrome cameras) providing two channels each and the two video cameras for visible light (RGB cameras) providing an additional six channels. The system is then designed so that these N detection channels provide optimal tissue contrast for the respective application. This is achieved by ensuring that all N channels differ in at least one property, e.g., spectrum and / or polarization.

[0093] A first possible embodiment of a system with 8 detection channels is illumination with 8 different polarizations, which are spectrally separated, and detection with 8 detectors, each analyzing with a single polarization in a spectrally separated manner. A second possible embodiment of a system with 8 detection channels is illumination with 2 defined polarizations, which are spectrally separated, and detection with 8 detectors, wherein 4 detectors analyze each spectral range with 4 different analyzers.

[0094] The Figure 17Figure 1 schematically shows a method according to the invention for generating an image, preferably a stereoscopic image, with polarization contrast of an object using a previously described visualization arrangement according to the invention, for example, a visualization arrangement of a surgical microscope, in the form of a flowchart. The method comprises, in step 41, the illumination of the object by means of the illumination device; in step 42, the detection of light waves emitted by the object after an interaction with the illuminated light waves, using the at least three video cameras or the at least two polarization cameras; and in step 43, the generation of a preferably stereoscopic image with polarization contrast based on a generated polarization state of the illuminated light waves and / or an analyzed polarization state of the detected light waves.For specific implementation variants of the procedure, please refer to the explanations regarding the . Figures 1 to 16 referred. Reference symbol list:

[0095] 1 Operating microscope with visualization setup 2 Video camera 3 Video camera 4 Illumination device 5 Object area, object 6 Beam path 7 Variable focal length optics (varioscope) 8 Zoom optics 9 Video lens 10 Laser autofocus device 11 Surround camera 12 Beam splitter 13 Evaluation device 14 (Stereoscopic) imaging device 15 (Image) data transmission 16 Pixel 17 Polarizing camera 19 Iris element 20 Polarizing filter device 21 Polarizing filter device 22 Polarizing filter device 23 Polarizing filter device 24 Polarizing filter device 31 Wavelength range 32 Wavelength range 33 Wavelength range 34 Polarizing bandpass filter 41 Incident light waves 42 Capture of light waveswhich are emitted by the object after an interaction of the object with the incident light waves 43 Generating an image with polarization contrast based on a generated polarization state of the incident light waves and / or an analyzed polarization state of the detected light waves I Intensity T Transmission λ Wavelength s Linear polarization p Linear polarization P0 Polarizer below 0 degrees P90 Polarizer below 90 degrees P45 Polarizer below 45 degrees P135 Polarizer below 135 degrees PC Circular polarizer PN Neutral polarizer,

Claims

1. Visualization arrangement (1) for microsurgery, comprising an imaging apparatus (14), an illumination device (4) and a polarization-determining arrangement, characterized in that the polarization-determining arrangement comprises at least two video cameras (2) for capturing multicoloured visible light and at least one further video camera (3), with each of the three aforementioned video cameras (2, 3) being assigned an individual partial beam path in the beam path (6), a plurality of polarization-filtering devices (20-24) and an evaluation device (13), wherein at least one polarization-filtering device (21-24) is arranged in the beam path (6) upstream of each of three of the at least three video cameras (2, 3), wherein the polarization-filtering devices (20-24) are set or settable such that the polarization filters (20-24) arranged in the beam path (6) upstream of the at least one specified further video camera (3) and at least one of the aforementioned video cameras (2) for capturing multicoloured visible light differ from one another in terms of their polarization effect, wherein the evaluation device (13) is designed to create image representations with polarization contrast using the images captured by the video cameras (2, 3) and to display said image representations by means of the imaging apparatus (14).

2. Visualization arrangement (1) according to Claim 1, characterized in that the evaluation device (13) is designed to display the created image representations with polarization contrast by means of the imaging apparatus (14) in a manner overlaid with white-light image representations captured by means of at least two video cameras (2) for capturing multicoloured visible light.

3. Visualization arrangement (1) according to Claim 1 or 2, characterized in that at least one polarization-filtering device (20) is arranged in the beam path (6) downstream of the illumination device (4) and upstream of an object space region (5) and / or at least one of the polarization-filtering devices (20-24) comprises a plurality of polarizers that differ from one another.

4. Visualization arrangement (1) according to any of Claims 1 to 3, characterized in that the at least one further video camera (3) is designed to capture monochrome light, or at least one of the aforementioned video cameras (2, 3) takes the form of a polarization camera.

5. Visualization arrangement (1) according to Claim 4, characterized in that at least one polarization-filtering device (22, 23) arranged upstream of a video camera (2) for capturing multicoloured visible light comprises a circular polarizer.

6. Visualization arrangement (1) according to any of Claims 1 to 5, characterized in that the evaluation device (13) is designed to use the images captured by the video cameras (2, 3) to determine a set of Mueller matrix coefficients and to determine a polarization contrast derived from said coefficients.

7. Visualization arrangement (1) according to any of Claims 1 to 6, characterized in that a polarization-filtering device (20) arranged in the beam path (6) downstream of the illumination device (4) and upstream of an object space region (5) is configured to simultaneously polarize at least two defined, mutually deviating wavelengths in a manner deviating from one another and / or at least one of the polarization-filtering devices (20-24) comprises a wavelength filter and / or a wavelengthselective polarizer.

8. Visualization arrangement (1) according to any of Claims 1 to 7, characterized in that the illumination device (4) is designed to emit bichromatic light and / or the illumination device (4) is designed to emit polychromatic light, and a polarization-filtering device (20) arranged in the beam path (6) downstream of the illumination device (4) and upstream of an object space region (5) comprises at least one notch filter and / or a number of bandpass filters and / or characterized by at least one beam splitter (12) that is arranged in the beam path (6) between an object space region (5) and the video cameras (2, 3).

9. Visualization arrangement (1) for microsurgery, comprising an imaging apparatus (14), an illumination device (4) and a polarization-determining arrangement, characterized in that the polarization-determining arrangement comprises two polarization cameras (17), with each of the two polarization cameras (17) being assigned an individual partial beam path in the beam path (6), and an evaluation device (13), wherein the evaluation device (13) is designed to create image representations with polarization contrast using the images captured by the polarization cameras (17) and to display said image representations by means of the imaging apparatus (14), wherein the evaluation device (13) is designed to display the created image representations with polarization contrast by means of the imaging apparatus (14) in a manner overlaid with white-light image representations captured by means of the two polarization cameras (17).

10. Method for creating an image representation with polarization contrast of an object (5) by means of a visualization arrangement (1) for microsurgery according to any of Claims 1 to 9, characterized in that the method comprises the following steps: - radiating light waves (41) onto the object (5) by means of the illumination device (4), - capturing light waves (42), which are emitted by the object (5) following an interaction of the object (5) with the radiated-in light waves, by means of the at least three video cameras (2, 3) or the at least two polarization cameras (17), - creating an image representation with polarization contrast (43) on the basis of a generated polarization state of the radiated-in light waves and / or an analysed polarization state of the captured light waves.

11. Method according to Claim 10, characterized in that light waves in a defined polarization state are radiated-in by means of the illumination device (4) and a polarization-filtering device (20) arranged in the beam path (6) downstream of the illumination device (4) and upstream of the object (5) and / or the polarization state of the received light waves is analysed by means of the at least three video cameras (2, 3) and the polarization-filtering devices (21-24) arranged upstream of said video cameras in the beam path (6) and / or by means of the polarization cameras (17).

12. Method according to either of Claims 10 and 11, characterized in that the evaluation device (13) is used to create an image representation with polarization contrast on the basis of an analysed polarization state of the captured light waves, wherein a set of Mueller matrix coefficients is determined by means of the images captured by the video cameras (2, 3) and / or the polarization cameras (17), and a polarization contrast derived from said coefficients is determined.

13. Method according to any of Claims 10 to 12, characterized in that the image representation with polarization contrast is created within a time interval of less than 50 ms, and / or the resolution of the stereoscopic image representation with polarization contrast created deviates from the resolution of a corresponding image representation without polarization contrast by less than 10 percent.

14. Method according to Claim 13, characterized in that the image representation with polarization contrast is created within a time interval of less than 50 ms and displayed in a manner overlaid on a multicoloured image representation.

15. Microscope comprising a visualization arrangement (1) according to any of Claims 1 to 9 or designed to carry out a method according to any of Claims 10 to 14.