Visualization Assembly for Microsurgery

Abstract

The present invention relates to a visualization assembly (1) for microsurgery, comprising an imaging device (14), an illumination device (4), and a polarization determination assembly, which comprises at least two video cameras (2) and at least one further video camera (3) designed to capture light waves of a plurality of light wavelengths in the visible wavelength range, wherein an individual partial beam path of a beam path (6) is assigned to each of the three mentioned video cameras (2, 3), a plurality of polarization filter devices (20-24), and an evaluation device (13), wherein the at least one polarization filter device (21-24) is arranged to filter the light waves of three of the at least three video cameras (2, 3) in front of each other. The polarizing filter devices (20-24) arranged in each beam path (6) are adjusted or adjustable so that the polarizing filters (20-24) arranged in the beam path (6) in front of the at least one further video camera (3) mentioned and the at least one video camera (2) designed to capture light waves of multiple light wavelengths in the visible wavelength range are different from each other in their polarization effect, and the evaluation device (13) is designed to generate images with polarization contrast from the images captured by the video cameras (2, 3) and display said images by the imaging device (14).

Description

[Technical Field]

[0001] The present invention relates to a visualization arrangement for microsurgery (e.g. for a surgical microscope) comprising an imaging device for generating an image representation with polarization contrast (e.g. a stereoscopic imaging device for generating a stereoscopic image representation with polarization contrast). The present invention also relates to a method for generating an image representation with polarization contrast (e.g. a stereoscopic image representation with polarization contrast) of an imaged object by means of a visualization arrangement for microsurgery. Furthermore, the present invention relates to a microscope (e.g. a surgical microscope). [Background technology]

[0002] Surgical microscopes are used in various fields of microsurgery, primarily in neurosurgery, spine surgery, ENT surgery, and ophthalmology. They are particularly characterized by their large working distances (200–600 mm) and moderate magnification (up to approximately 20x), allowing for stereoscopic imaging. These features allow for the use of surgical instruments in a sterile surgical field while simultaneously viewing the surgical site in stereo. In recent years, there has been a shift from analog to digital systems. Digital systems use cameras and 3D monitors or other 3D playback systems (head-mounted displays (HMDs), digital eyepieces (boom)) for image recording and presentation.

[0003] An important driving force behind the development of surgical microscopes is the user's desire for tissue differentiation. Depending on the field and application, this can be the differentiation of tumor tissue from healthy tissue, the differentiation of white matter from gray matter in the brain, the improved representation of blood vessels and nerves, the visualization of phase objects (lens, lens capsule, etc.) during cataract surgery, or the visualization of membranes during retinal surgery. Digital surgical microscopes offer a major advantage for improved tissue differentiation, as the camera system used can be utilized for this purpose.

[0004] From the user's perspective, especially in the field of neurosurgery, there are several requirements for tissue differentiation technology: (i) Differentiation of various tissue types must be performed in real time with respect to the stereoscopic image data, i.e., without any noticeable time delay for the user, e.g., the surgeon. For digital systems, this time is typically less than 50 ms. (ii) Tissue differentiation must be performed across the entire surgical site, which is typically approximately 10–50 mm in diameter. The resolution of tissue differentiation should correspond to the resolution of the stereoscopic image data (analog or digital), but can be lower. (iii) Tissue differentiation must be intuitively interpretable by the surgeon, and its practical significance must be supported by clinical studies. (iv) Tissue differentiation must be able to be switched on and off as needed. (v) The technology used for tissue differentiation must not significantly increase the cost of the surgical microscope, especially its footprint. (vi) Ideally, tissue differentiation should be performed without the use of markers or dyes, because their approval process is time-consuming and frequently causes adverse effects in patients.

[0005] The scientific literature describes many techniques that can be used for tissue differentiation. In this context, optical techniques offer many advantages over non-optical methods such as ultrasound due to their excellent integration and non-contact measurement capabilities. The most important optical techniques for tissue differentiation are fluorescence / autofluorescence detection (continuous and / or time-resolved), laser Doppler and laser speckle imaging, optical coherence tomography (OCT), Raman spectroscopy (coherent or non-coherent), narrowband imaging, and the detection of the influence of biological tissue on the polarization state of light. Despite the large number of scientific papers published, only a small number of commercialized technologies have been developed, due to the difficulty of meeting the aforementioned requirements.

[0006] Therefore, camera-based fluorescence techniques have become increasingly popular in recent years, particularly for both surgical microscopes and endoscopes, because they best meet the aforementioned requirements. These techniques are currently based on three medically approved dyes: ICG, NAF, and 5-ALA. These dyes are used for tumor / non-tumor differentiation and blood flow visualization. While these fluorescent techniques using the three approved dyes meet requirements (i) through (v), they do not meet requirement (vi). That is, they are only available when used in combination with pharmaceuticals. A further drawback of these fluorescence options lies in the fact that they cannot differentiate all applicable tissue types. Some tumors do not absorb the aforementioned dyes. Furthermore, in neurosurgery, maintaining brain function during surgery is crucial. For this purpose, it is necessary to identify brain fiber tracts (white matter) and differentiate them from tumors or the gray matter of the cerebral cortex. This is currently not possible with any of the aforementioned dyes. Therefore, there is a great need for techniques to differentiate between tumors, blood vessels, and white and gray matter tissues, especially in neurosurgery.

[0007] Among the aforementioned techniques, polarized light has the advantage that it is sensitive to different tissue types, without the need for dyes or pharmaceuticals, due to the underlying physical processes. At the cellular level, tumors exhibit chaotic structures, while fiber tracts in particular represent highly ordered zones. It is known from the literature that such structures affect the polarization of irradiated light differently.

[0008] The following section provides a detailed description of the formalism of the Stokes vector and Mueller matrix for the interaction of optical elements with tissue at a surgical site due to partially polarized light. The Mueller matrix is ​​a 4x4 transformation matrix for the Stokes vector of the illuminating light, which, after multiplication, provides the Stokes vector at the detector location. Knowledge of the Mueller matrix and its 16 elements therefore contains all the information about how an object responds to partially polarized light. In the field of metrology, there are many polarimeters that measure the complete Mueller matrix at a point or plane (e.g., https: / / mountainphotonics.de / product / axo-axostep / ). A Mueller polarimeter consists of components such as a light source, a PSG (Polarization State Generator), a PSA (Polarization State Analyzer), and a detector (point or plane). In this case, the PSG and PSA can be realized in different ways, for example, by rotating a phase difference element or by fixing it with a ferroelectric element.For general technical background, see W. Singer, M. Totzeck, H. Gross, Handbook of Optical Systems, Vol. 2 "Physical Image Formation", Chap. 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 magneto-optic garnet films", Appl. Opt. 30 (1991) 1730-1734 [4], A. Pigula, N. T. Clancy, S. Arya, G. B. Hanna, D. S. Elsonin: Video-rate dual polarization multispectral endoscopic 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]

[0009] In the following, we describe how to determine polarization contrast, specifically for tissue under examination, from the Stokes vector. The Stokes vector is a conventional way to describe partial polarization states in polarization optics [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 a specific polarizer.

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[0010] Thus, the Stokes parameter S0 represents the intensity of light. S1 specifies how large the difference is between the components of light linearly polarized in the x and y directions, i.e., the components of horizontal and vertical linear polarization. S2 specifies how large the difference is between the components of light linearly polarized at 45° and 135°, i.e., the components of diagonal linear polarization. S4 specifies how large the difference is between the components of light polarized right and left, i.e., the components of circular polarization.

[0011] An important characterization parameter of light in tissue contrast is the degree of polarization g, which is the polarized component of the total intensity,

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[0012] In the case of polarized illumination, the degree of polarization generally decreases as a result of interaction with tissue, especially as a result of multiple reflections. Since structures are often linear (e.g., nerve fiber bundles), the degree of linear polarization g lin is particularly important.

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[0013] Similarly, the degree of circular polarization g circ teeth,

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[0014] The principle of measuring the Stokes vector is explained below. Although six different polarizers and the measurement of the total intensity affect the definition of the Stokes vector, four polarizers are sufficient to measure the Stokes parameters unambiguously. The reason for this is that the sum of two orthogonal polarization states already represents the total intensity, i.e. I0=P0+P 90 =P 45 +P 135 =P R +P L (5) Due to the fact that

[0015] Therefore, the Stokes vector (1) can also be written as:

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[0016] In the following, we will describe the Mueller matrix and its information content, especially for tissue. The polarization effect of an object such as tissue consists of transforming the incident Stokes vector into an emergent vector. In the linear domain, this transformation is described by multiplication with a 4x4 matrix, the Mueller matrix, as follows:

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[0017] The individual Mueller matrix elements have a simple meaning in themselves: they describe the excitation of one Stokes parameter by another. Thus, for example, M 12 represents the excitation of S1 by S2.

[0018] Decomposing the Mueller matrix into fundamental polarization matrices is important for describing tissue polarization, as described in, for example, [2]. One such decomposition is the Lew-Chipman polar decomposition, in which the Mueller matrix is ​​expressed as the product of the depolarizing Mueller matrix, the retarder Mueller matrix, and the biabsorber Mueller matrix, as follows: M=M Dia M Ret M Depol (9) The depolarization Mueller matrix is

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[0019] In addition to this well-known decomposition, the polarimetry literature contains many decompositions of the Mueller matrix as a function of fundamental matrices [2]. This decomposition provides a unique and correct physical representation of the Mueller matrix, which consists of depolarization, phase shift, and biabsorption. However, a correct decomposition also requires measurement of the entire Mueller matrix. In such cases, the Mueller matrix decomposition is the preferred analytical form.

[0020] In principle, however, polarizers are not perfect and must themselves be described by Mueller matrices. However, as shown in [4] and explained below, this can be taken into account in the measurement process. At the stage of measuring the Stokes vector, the fact that the available components are not polarization-optically ideal must already be taken into account. However, it can be assumed that they do not depolarize. Their effect on the partial polarization is therefore described by a known, but not necessarily simple, Jones matrix. For example, a polarizer may only have a degree of polarization of 0.9. It certainly makes more sense to take this property into account during evaluation instead of incorporating it into the error budget. According to [4], a general method for measuring the Stokes vector (or polarization matrix) can be established, which only assumes that the Jones matrices of the polarization-modifying components are known, without assuming that they have specific values. The basis of this method is the linearity of the polarization matrix transformation in the Jones matrix, as follows:

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[0021] Four intensity measurements at four different L were used to set up simultaneous linear equations, and P in can be determined,

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[0022] Coefficient A jk To determine I j The formula must be multiplied.

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[0023] In practical measurements, four different measurement Jones matrices must be realized using polarized optical components. There are various options for this. Standard methods are specified in [4] and utilize linear polarizers at 0°, 45°, and 90°, or a quarter-wave plate with a 90° slow axis followed by a 45° polarizer. Alternative measurement methods use a rotating quarter-wave plate followed by a polarizer. Naturally, further configurations are possible. For a "good" measurement method, the accuracy of the measurement no longer depends on how accurately the components maintain a given value (e.g., retardation, extinction ratio), but only on how well this value is known. A further important variable regarding measurement accuracy is the extent to which the components span the orthonormal basis of the Jones vector. In this case, the relative error of the Stokes vector components is directly introduced into the Mueller matrix. However, considering the accuracy of the components, the smaller the relevant basis vector realized by the measurement method (i.e., the sensitivity of the measurement method to a given Stokes vector component) becomes, the larger the relative error becomes.

[0024] DE 10 2017 100 904 A1 describes an image conversion module for a microscope designed for polarized light measurements with a polarizing mask. U.S. Patent Application Publication No. 2016 / 091702A1,German Patent Application Publication No. 10242983A1, Chinese Patent Application Publication No. 107490851A, German Patent Application Publication No. 102018110806A1, and International Publication No. 2016170816A1 , and also 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.3,12 February 2018(2018-02-12),pages1097-1110 describe a surgical microscope designed for at least partial polarized light determination.

[0025] The biggest challenges to integrating a complete Muller polarimeter into a surgical microscope, or in general any microscope requiring real-time evaluation, are the requirements of (i) real-time capability, (ii) stereoscopic vision, and (v) small installation space and low cost (see above). For this reason, only simple crossed linear polarimeters for illumination and observation have been implemented in surgical microscopes to date (see below). The literature describes various approaches to polarimeters to achieve the aforementioned requirements, but so far without success.

[0026] The ZEISS EXTARO surgical microscope (https: / / www.zeiss.de / meditec / produkte / zahnheilkunde / operationsmikroskope / extaro-300.html) exclusively uses linear polarizers. The first polarizer is installed so that it can be rotated in and out of the illumination beam path of the surgical microscope, and two further polarizers are integrated into the two stereo beam paths, which can also be rotated in and out of the illumination at right angles to the polarizers. Applied to, the polarizers are used to reduce reflections on the tooth surface ("no-glare mode").

[0027] In the "3x3 Mueller Polarimetric Endoscope" shown in Figure 8 of J. Qi and D.S. Elson, Mueller polarimetric imaging for surgical and diagnostic applications, J. Biophotonics 10, 950-982 (2017) / DOI 10.1002 / jbio.201600152 [2], a linear polarizer is firmly positioned upstream of the illumination exit at the tip of the endoscope. The endoscope rotates around its optical axis and is aligned at three different positions during the measurement process. In this way, three different alignments of the linearly polarized light can be achieved in the illumination. A filter wheel incorporating three different polarizers is mounted in front of the camera in the observation beam path. This endoscope can be used to determine a 3x3 submatrix of the Mueller matrix. The measurement time is 11.6 seconds. Rotating the endoscope during clinical use is nearly impossible.

[0028] [2] also describes an endoscope for measuring the complete Mueller matrix using rotational PSG and time-series PSA with a measurement time of 30 seconds (see Figure 10). However, the long measurement time and the presence of rotating elements make this endoscope unsuitable for clinical use or for applications requiring real-time evaluation. [2] also describes a stereo endoscope with a linear polarizer covering the illumination and one stereo channel at the tip. The second stereo channel measures polarized light perpendicular to it (see Figure 11). In addition, the polarized light measurement is combined with spectral narrowband imaging. While this endoscope meets the requirements for real-time capability and small installation space / low cost, it does not generate a stereoscopic image for users, such as surgeons. Furthermore, only a small portion of the Mueller matrix (a 2 × 2 submatrix) is determined, and important information about the sample's properties is not obtained.

[0029] 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" equipped with a ferroelectric modulator-based PSG and PSA. This module is mounted below the colposcope and can be rotated in and out. The measurement time is approximately 1.6 seconds, and a complete 4x4 Mueller matrix is ​​measured. In terms of optical structure, the colposcope is comparable to a surgical microscope. In this case, the polarimeter module is mounted below the main objective and has a monoscopic beam path. Therefore, this method does not offer real-time capabilities, stereoscopic vision, a compact design, or low cost.

[0030] Real-time (<50 ms) and large field of view (>1 cm diameter) stereoscopic tissue differentiation beyond the use of simple crossed polarizers is not yet known. Summary of the Invention [Problem to be solved by the invention]

[0031] Against this background, the problem that the present invention aims to solve is to provide an advantageous visualization arrangement for microsurgery, an advantageous method for generating an image representation with polarization contrast by means of a visualization arrangement for microsurgery, and a microscope, in particular a surgical microscope. [Means for solving the problem]

[0032] The aforementioned problem is solved by the visualization arrangement for microsurgery according to claims 1 and 13, 14 A method for generating an image representation with polarization contrast by means of a microsurgery visualization arrangement according to claim 1, 20The problem is solved by a microscope according to the invention. The dependent claims contain further advantageous configurations of the invention.

[0033] The visualization arrangement for microsurgery (e.g., for a surgical microscope) according to the present invention comprises an imaging device (preferably a stereoscopic imaging device), an illumination device, and a polarization determination arrangement. The polarization determination arrangement comprises at least two video cameras designed to capture light waves of multiple light wavelengths in the visible wavelength range (i.e., the wavelength range from 400 nm to 780 nm), at least one additional video camera (preferably two additional video cameras), multiple polarization filtering devices, and an evaluation device. Individual partial beam paths of the beam path are assigned to each of the three video cameras. Thus, the three video cameras can be arranged next to each other in the beam path, or, in other words, parallel to each other with respect to the beam path. In this context, this does not necessarily mean a spatial or geometric parallel arrangement or an arrangement adjacent to each other, but rather an arrangement that allows the individual capture of light waves in different partial beam paths of the beam path by each video camera.

[0034] The at least two video cameras for capturing polychromatic visible light may be, for example, RGB cameras, and the at least one further video camera may be, for example, a fluorescence camera.

[0035] At least one polarization filtering device is arranged upstream of each of three of the at least three video cameras, for example, in the beam path upstream of each of the three video cameras. Optionally, at least one polarization filtering device can be arranged downstream of the illumination device and upstream of the beam path of the object space region (for example, the object to be imaged or the object plane). The polarization filtering device is set or configurable so that the polarization filters arranged in the beam path upstream of at least one designated additional video camera and at least one of the video cameras designed to capture light waves of multiple light wavelengths in the visible wavelength range differ from each other. Thus, at least two, preferably three, polarization filtering devices are set or configurable so that they are offset from each other upstream of the video cameras. For example, the polarization filtering device is set or configurable so that the three polarization filters arranged in the beam path upstream of the three video cameras differ from each other in polarization effect, i.e., each of the three video cameras receives light simultaneously with the other two video cameras, and the received light differs in polarization from that of the other video cameras.

[0036] In this case, the object to be imaged is also understood to be a subject or a partial area of ​​a subject, such as, for example, human, animal or plant tissue.

[0037] The evaluation device is designed to use the image captured by the video camera to generate an image representation (e.g., a two-dimensional or three-dimensional image representation) with polarization contrast and display said image representation by an imaging device, preferably displaying it stereoscopically. In this process, the generated image representations with polarization contrast can be superimposed on the beam path of the imaging device. These image representations can also be partially transparently overlaid on an image representation without polarization contrast. Thus, the generated image representations with polarization contrast can be superimposed or masked. In this process, the polarization filtering device can be switchable on / off.

[0038] In an advantageous variant, the evaluation device is designed to display the generated image representation with polarization contrast overlaid on a white-light image representation captured by at least two video cameras designed to capture light waves of multiple light wavelengths in the visible wavelength range using an imaging device. The at least two video cameras may be the aforementioned at least two video cameras. However, they may also be more than three video cameras. In particular, a polarizing filtering device may not be arranged in front of at least one of the video cameras for capturing polychromatic visible light, at least sequentially. In this way, a high-resolution polychromatic image representation can be generated by at least one of the video cameras for capturing polychromatic visible light, and the generated image representation with polarization contrast can be overlaid on the high-resolution polychromatic image representation. For example, the polarizing filtering device may be switchable in front of at least one of the video cameras for capturing polychromatic visible light so that an image representation with an upstream polarizing filter and an image representation without the upstream polarizing filter are alternately captured, preferably at intervals of less than 100 ms (particularly less than 40 ms). As a result, high-resolution image representations of the object to be imaged with and without polarization contrast can be captured using the same video camera. Alternatively, at least one additional video camera may be present, at least one video camera designed to capture a multicolor image representation of the object to be imaged without polarization contrast. The image representation with polarization contrast can be displayed overlaid on the captured image representation.

[0039] For example, white light can be understood to mean light with a broadband color spectrum. In this case, the wavelengths may be substantially in the visible range. The distribution of wavelengths is usually continuous. The broadband color spectrum of a "white light source" produces the impression of white in humans. In this case, the color impression produced by the eye is relevant. Therefore, this is a physiological effect, not a physical effect. That is, the impression of white may be based on different spectra limited to the visible range.

[0040] The visualization arrangement can be configured as a visualization arrangement of a microsurgery device, for example as a visualization arrangement of a surgical microscope, in particular a surgical microscope designed for neurosurgery. The visualization arrangement preferably has a fully digital configuration.

[0041] When the visualization arrangement is configured as a component of a microscope, the microscope can be configured as a fully digital microscope, in particular a surgical microscope. The visualization arrangement can be designed to record and display white light and / or fluorescent video data in real time stereoscopically, in particular displaying said data in real time overlaid with a generated image representation with polarization contrast. When used as a component of a surgical microscope, the surgical microscope can preferably be designed for neurosurgery. It can have an object surface or object plane with a diameter in the range of 10 mm to 50 mm. Preferably, the resolution of the generated image representation with polarization contrast is lower than the resolution of the (stereo) image representation without polarization contrast displayed by the (stereo) imaging device, or the resolutions can match each other. For example, the aforementioned resolutions can deviate from each other by less than 10%.

[0042] In a further variant, the determined polarization contrast values ​​can be stored adaptively for a specific application and displayed on or off. For example, in neurosurgical applications, the type of tissue imaged with polarization resolution or tissue characteristics derivable from the polarization-resolved image representation can be displayed. For this purpose, the complete Mueller matrix can be determined for each tissue type in clinical studies. Clinically relevant elements or elements generally relevant to each application can be derived for each tissue type from the Mueller matrix analysis. Then, within the scope of a visualization arrangement, e.g., within a microscope, only the relevant elements of the Mueller matrix can be determined or the Stokes vector components required for this purpose can be measured. The visualization arrangement can be designed to determine a fixed reduced Mueller matrix.

[0043] The advantages of the visualization arrangement according to the invention are that it provides an integrated polarimetry technique that meets the requirements for real-time capability, small installation space, low cost, and optionally stereoscopic vision. In its variant as a visualization arrangement for a surgical microscope, the invention allows improved tissue differentiation, particularly in the field of neurosurgery. The visualization arrangement according to the invention makes it possible to simultaneously capture data that allows the determination of the Stokes vector and the complete Mueller matrix, or the determination of the Mueller matrix elements or coefficients, which are essential for the respective application.

[0044] In an advantageous variant, at least one of the polarization filtering devices arranged upstream of three, e.g., four, video cameras, e.g., at least three, e.g., four, polarization filtering devices, preferably all of the aforementioned polarization filtering devices, includes a plurality of different polarizers, e.g., at least four different polarizers. At least one of the polarization filtering devices may include a filter wheel for switching between the plurality of different polarizers. In this way, each of the plurality of polarizers can be introduced into the beam path. For example, at least one of the polarization filtering devices may include at least three, in particular four, linear polarizers and, optionally, at least one circular polarizer. For this purpose, at least one of the polarization filtering devices may include one or more phase difference elements, at least a variable phase shifter, and / or a ferroelectric element, etc.

[0045] In an advantageous configuration of the variant with four cameras, i.e., with appropriate selection of the polarizers of the individual polarization filtering devices introduced into the beam path, at least three, preferably all four, of the four polarizers placed upstream of the video camera differ from each other in terms of their polarization effects. For example, three of the polarizers are linear polarizers selected from the polarizers P0, P45, P90, and P135 shown in FIG. 3, one polarizer can be a circular polarizer, or three or all four can be linear polarizers. Filters with identical polarization effects can be placed or set upstream of a video camera designed to capture light waves of multiple light wavelengths in the visible wavelength range. Preferably, their polarization effects are orthogonal to those of the polarizers optionally placed downstream of the illumination device and upstream of the object to be imaged.

[0046] In an advantageous variant, at least one, for example two, of the at least one further video camera is designed to capture monochrome light, i.e. light of a defined wavelength or a defined wavelength range, in particular fluorescent light, where the captureable wavelength range may extend beyond the visible wavelength range.

[0047] In a further variant, at least one of the aforementioned video cameras, for example, the three aforementioned video cameras, can take the form of a polarization camera. For example, the polarization camera can include four linear polarizers at the pixel level. The polarization camera can include at least one circular polarizer at the pixel level, for example, instead of one of the four linear polarizers, i.e., three linear polarizers and one circular polarizer. A polarization filtering device located upstream of a video camera that does not take the form of a polarization camera, i.e., a video camera designed to capture light waves of multiple light wavelengths in the visible wavelength range, can include or be configured as a circular polarizer. This can be achieved by combining a linear polarizer with a retarder, for example, in the form of a 0-degree quarter-wave plate element.

[0048] The evaluation device is advantageously designed to determine, by means of the images captured by the video camera, a set, in particular a finite set, of Mueller matrix coefficients and to determine (eg calculate) the polarization contrast derived therefrom.

[0049] In a particularly advantageous configuration, a polarization filtering device, optionally arranged in the beam path downstream of the illumination device and upstream of the object space region, is designed to simultaneously polarize at least two defined, mutually offset wavelengths, e.g., two defined, mutually offset wavelength ranges, in a mutually offset manner, i.e., different from each other. This allows a relatively large amount of data to be simultaneously acquired, and thus a relatively large number of Mueller matrix coefficients to be determined or established. As a result, stronger polarization contrasts can be determined, and thus high-quality image representations with polarization contrasts can be generated. Furthermore, simultaneously available detection channels (e.g., the number of camera sensors in an RGB camera), optionally spectrally encoded detection channels, can be used for different polarization information about the object under inspection. Thus, polarization and spectrum can be designed so that multiple detection channels (e.g., each detection channel) provide different information (e.g., tissue information).

[0050] At least one of the polarization filtering devices may include a color filter or a wavelength filter, and / or a wavelength-selective or wavelength-specific polarizer, by which the above configurations can be realized. Each polarization filtering device may include, for example, a notch filter, in particular a polarization notch filter, and / or a bandpass filter, in particular a polarization bandpass filter.

[0051] In general, the polarization filtering device may include filters for fluorescence and / or polarization (particularly wavelength-specific polarization), for example, a first polarization state for at least one first wavelength or first wavelength range and a second polarization state for at least one second wavelength or second wavelength range may be set or configurable.

[0052] The illumination device can be designed to emit dichromatic or polychromatic light. Preferably, the illumination device is designed to emit polychromatic light, and the polarizing filtering device arranged in the beam path downstream of the illumination device and upstream of the object space region comprises at least one, e.g. two notch filters, preferably polarizing notch filters, and / or at least one, e.g. two bandpass filters, preferably polarizing bandpass filters.

[0053] Furthermore, the visualization arrangement may include at least one beam splitter, for example a dichroic beam splitter, which may be arranged in the beam path between the object space region and the video camera.

[0054] At least one of the video cameras designed to capture or receive light waves of multiple light wavelengths in the visible wavelength range can be configured as a three-chip camera or a one-chip camera.

[0055] A visualization arrangement for microsurgery according to the present invention, which is an alternative to the visualization arrangement described above, comprises an imaging device (e.g., a stereoscopic imaging device), an illumination device, and a polarization determination arrangement. The polarization determination arrangement comprises two polarization cameras, each of which is assigned a respective partial beam path of the beam path, and an evaluation device. The evaluation device is designed to generate an image representation with polarization contrast using the images captured by the polarization cameras and to display said image representation, preferably stereoscopically, by the imaging device. The alternative visualization arrangement according to the present invention provides a solution equivalent to the visualization arrangement according to the present invention described above. Both of these variants use the same technical effect for generating an image representation with polarization contrast and have the same features and advantages as those described in detail above. In particular, the alternative visualization arrangement according to the present invention may include the aforementioned features and characteristics that are optional in the context of the initially described visualization arrangement according to the present invention.

[0056] ReviewThe polarization device is designed to display the generated image representation with polarization contrast overlaid on a white-light image, which is captured by two polarization cameras, where the display is performed by an imaging device.

[0057] A method according to the invention for generating an image representation with polarization contrast (e.g. a stereoscopic image representation with polarization contrast) of an object by means of a visualization arrangement according to the invention for microsurgery (in particular for a surgical microscope) as described above comprises the following steps: an illumination device illuminates the object with light waves, in particular in the visible wavelength range, and optionally with light waves in a higher wavelength range; at least two polarization cameras or at least three video cameras capture or receive light waves emitted by the object after interaction of the illuminated light waves with the object; based on the generated polarization state of the illuminated light waves and / or the analyzed polarization state of the captured or received light waves, an image representation with polarization contrast, preferably a stereoscopic image representation with polarization contrast, is generated. The method according to the invention has the already described features and advantages of the visualization arrangement according to the invention.

[0058] In an advantageous variant, light waves with a defined polarization state are irradiated by an illumination device and a polarization filtering 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 by the aforementioned video camera and a polarization filtering device arranged in the beam path upstream of the video camera. The evaluation device can be used to generate an image representation (e.g. a stereoscopic image representation) with polarization contrast based on the analyzed polarization state of the captured or received light waves, and a set of Mueller matrix coefficients is determined by the images captured by the video camera and / or polarization camera, and a polarization contrast derived from said coefficients is determined (in particular calculated).

[0059] The image representations (e.g., stereoscopic image representations) with polarization contrast are preferably generated within a time interval of less than 50 ms. The resolution of the generated image representations (e.g., stereoscopic image representations) with polarization contrast preferably deviates from the resolution of the corresponding image representations (e.g., stereoscopic image representations) without polarization contrast by less than 10%. Particularly preferably, the image representations (e.g., stereoscopic image representations) with polarization contrast are generated within a time interval of less than 50 ms and displayed overlaid on the multicolor image representations (e.g., stereoscopic image representations).

[0060] Within the scope of the method according to the present invention, photogrammetry can be applied to a video signal to identify corresponding pixels, for example in a stereo channel, and perform polarization evaluation. In this process, a numerical value reflecting the polarization characteristics can be calculated for each pixel. From this, a color value reflecting the polarization characteristics can be derived for each pixel. In particular, the polarization characteristics can be represented stereoscopically in real time, either by themselves or overlaid on a white-light image.

[0061] The microscope according to the invention, which may be a surgical microscope (e.g. a neurosurgical microscope), comprises the visualization arrangement according to the invention described above and / or is designed to carry out the method according to the invention described above. It has the features and advantages already specified above. The microscope according to the invention is preferably constructed stereoscopically and / or partially or completely digitally.

[0062] A microscope, in particular a surgical microscope, may include an optical system unit with a variable focal length, i.e. an optical system unit with a variable focus (varioscope) and / or at least one objective lens, arranged in the beam path upstream of at least one video camera, and / or at least one zoom optical system unit and / or a peripheral camera, i.e. a video camera for capturing the spatial region around the object region to be imaged with the microscope.

[0063] The present invention will be described in detail below based on exemplary embodiments with reference to the accompanying drawings. The present invention will be more particularly illustrated and described in more detail by preferred exemplary embodiments, but the present invention is not limited to the disclosed examples, from which those skilled in the art can derive other variations without departing from the scope of protection of the present invention.

[0064] The figures are not necessarily accurate in detail or to scale and may be presented enlarged or reduced for greater clarity. As such, it should be understood that the functional details disclosed herein are not intended to be limiting, but merely an exemplary basis to guide those skilled in the art in using the present invention in various ways.

[0065] As used herein, the term "and / or," when used with a list of two or more elements, means that any of the listed elements may be used alone, or any combination of two or more of the listed elements may be used. For example, if a structure is described that includes components A, B, and / or C, the structure may include A alone, B alone, C alone, a combination of A and B, a combination of A and C, a combination of B and C, or a combination of A, B, and C. [Brief explanation of the drawings]

[0066] [Figure 1] 1 shows, in block diagram form, a surgical microscope according to the invention, having a visualization arrangement according to the invention; [Figure 2] 1 shows, in block diagram form, a schematic representation of the polarized optical mode of operation of a visualization arrangement according to the invention; [Figure 3] 1 illustrates a schematic diagram of an exemplary polarizing filter. [Figure 4] 2 shows, in block diagram form, a schematic representation of the polarized optical operation mode of an exemplary variant of a visualization arrangement according to the invention; [Figure 5] 2 shows, in block diagram form, a schematic representation of the polarized optical operation mode of an exemplary variant of a visualization arrangement according to the invention; [Figure 6] 2 shows, in block diagram form, a schematic representation of the polarized optical operation mode of an exemplary variant of a visualization arrangement according to the invention; [Figure 7] 2 shows, in block diagram form, a schematic representation of the polarized optical operation mode of an exemplary variant of a visualization arrangement according to the invention; [Figure 8] 2 shows, in block diagram form, a schematic representation of the polarized optical operation mode of an exemplary variant of a visualization arrangement according to the invention; [Figure 9] 1 shows a schematic diagram of the principle of a polarization camera. [Figure 10] 1 shows two diagrams that illustrate possible illuminations of the object area. [Figure 11] 11 shows a schematic diagram illustrating the realization of illumination as shown in the lower part of FIG. 10 by means of a polarizing notch filter. [Figure 12] 12 shows a schematic realization of the variant shown in FIG. 11 by means of a polarizing bandpass filter. [Figure 13] 2 shows, in block diagram form, a schematic representation of the polarized optical operation mode of an exemplary variant of a visualization arrangement according to the invention, using two different wavelengths; [Figure 14] 1 shows, in block diagram form, a schematic representation of the polarized optical operating mode of an exemplary variant of a visualization arrangement according to the invention, using two different wavelengths and two polarization cameras; [Figure 15] 2 shows, in block diagram form, a schematic representation of the polarized optical operation mode of an exemplary variant of a visualization arrangement according to the invention, using two different wavelengths; [Figure 16] 1 shows a schematic representation of the spectral resolution of a prism and a filter. [Figure 17] 1 illustrates a method according to the present invention in the form of a flow chart. DETAILED DESCRIPTION OF THE INVENTION

[0067] FIG. 1 shows a schematic block diagram of a surgical microscope 1 according to the invention. For example, the surgical microscope 1 can be designed for applications within the scope of neurosurgery or spinal surgery. The surgical microscope 1 comprises an illumination device 4, a visualization arrangement having, for example, an object plane or object space region 5 in which an object to be imaged under magnification can be placed, a stereoscopic imaging device, and a polarization determination arrangement. The illumination device 4 is designed to illuminate the object space region 5, i.e., to irradiate the object with light waves. The beam paths are identified by arrows bearing the reference sign 6.

[0068] Preferably, microscope 1 takes the form of a fully digital microscope. Microscope 1 is preferably designed to record and display both white-light and fluorescent video data in real time and stereoscopically. This is achieved by using, in each case, two video cameras 2 (VIS cameras, e.g., RGB cameras) designed to capture light waves of multiple light wavelengths in the visible wavelength range, and at least one additional video camera 3, preferably two additional video cameras 3 (fluorescence cameras) as shown, configured as a monochrome camera for increased sensitivity and designed to capture fluorescent light. The two VIS cameras 2 are preferably three-chip or one-chip cameras. The fluorescent camera 3 can also be designed to capture light waves beyond the visible range.

[0069] Additionally, the microscope 1 includes an optical unit with a variable focal length (varioscope) 7, two zoom optical units 8, an aperture element 19, and two video objectives 9. In this case, the optical unit with a variable focal length (varioscope) 7, the two zoom optical units 8, and the two video objectives 9 are arranged in a beam path 6 between the object space region 5 or an object arranged in the object space region and the aforementioned video cameras 2, 3. In FIG. 1, a laser autofocus device 10 is arranged in the beam path 6 between the optical unit with a variable focal length 7 and the zoom optical unit 8. A beam splitter 12 is arranged in each beam path 6 between the video objectives 9 and the aforementioned video cameras 2, 3. The beam splitter 12 generates individual partial beam paths, which are assigned to each of the aforementioned video cameras 2, 3 in the beam path 6. Additionally, the microscope 1 optionally includes a peripheral camera 11 that can be used to capture a wide field of view around the object area captured by the microscope (e.g., a magnified surgical site) and can be used for tool tracking and navigation functions.

[0070] The polarization determination arrangement comprises, in addition to the aforementioned four video cameras 2, 3, a number of polarization filtering devices 20-24 and an evaluation device (not shown here). In this case, a respective polarization filtering device 21-24 is arranged in the beam path 6 upstream of each of the aforementioned four video cameras 2, 3, and the polarization filtering device 20 is arranged in the beam path 6 downstream of the illumination device 4 and upstream of the object space region 5. In this case, the polarization filtering devices 21-24 are set or can be set in each case such that the polarization filters 21-24 arranged in the beam path 6 upstream of at least one, preferably both, of the two designated further video cameras 3 and at least one, in particular both, of the aforementioned video cameras 2 designed to capture light waves of a number of light wavelengths in the visible wavelength range differ from each other in their polarization effect. In other words, the polarization setting of at least one polarizing device 22, 23 arranged upstream of one of the video cameras 2 designed to capture visible light (VIS camera) is different from the polarization setting of at least one polarizing device 21, 24 arranged upstream of one of the further video cameras 3 (e.g., a fluorescence camera) during operation.

[0071] The polarization determination arrangement allows the polarization state of the light emitted from the object 5 to be analyzed, and multiple polarization measurements can be performed simultaneously using multiple video cameras 2, 3. This allows the necessary data to be captured and evaluated in real time. To generate a polarization-resolved (e.g., three-dimensional) overall image of the object, for example, differently configured polarization filter wheels or different polarizers 20-24 can be placed in the beam path 6 upstream of the four cameras 2, 3 and downstream of the illumination device 4. On the one hand, these are equipped with excitation and observation filters suitable for the aforementioned fluorescence method options, while also including a polarizer suitable for the polarization measurements.

[0072] When using the alternative visualization arrangement according to the invention as described at the beginning, the video camera 2 is configured as a polarization camera. In this variant, the further video camera 3, the beam splitter 12 and the polarization filtering arrangements 20-24 can be omitted.

[0073] In the following, simplified diagrams are used for the polarization optics description of the system. Figure 2 shows, in block diagram form, a schematic polarization optics operating mode of the visualization arrangement according to the invention. In this case, an evaluation device 13 is used to analyze and evaluate the image data captured by the four cameras 2, 3 and combine the data to form a three-dimensional overall image with polarization contrast. The generated overall image is visualized by a stereoscopic imaging device 14 or displayed to the user. Data transfer between the video cameras 2, 3 and the evaluation device 13 and between the evaluation device 13 and the stereoscopic imaging device 14 is identified by the reference numeral 15. Within the scope of the analysis and evaluation of the acquired data, the Stokes vector or a part thereof is preferably determined, and multiple, preferably more than four, Mueller matrix coefficients are determined (in particular, calculated). The polarization contrast is determined using the determined Mueller matrix coefficients.

[0074] Figure 3 shows a schematic representation of exemplary polarizing filters and their designations. In this case, the polarizing effect of the filter is indicated by the direction of transmitted polarization. Polarizers 20-24 each include a number (preferably multiple) of different polarizers, such as one or more of the polarizers shown in Figure 3. Preferably, the polarization is individually settable in each of the polarizing filtering devices.

[0075] To measure the complete Stokes vector, four different polarizers are required at filter positions 21-24. An example is shown in Figure 4, where the polarizers can also be labeled differently among the four filter positions 21-24. In a surgical microscope, the linearly polarized component may be of primary interest, so the circular polarizer can optionally be omitted. The circular polarizer can then be replaced with, for example, a 135° filter to provide redundancy in determining the overall intensity, as shown in Figure 5.

[0076] In a further variant shown in Figure 6, identical polarizing filters are placed or installed in front of two video cameras 2 for visible light (VIS or RGB cameras) so as not to interfere with stereoscopic imaging. In this case, it is advantageous if the polarization of the illumination 4, 20 is set orthogonal to the polarization of the filters 22, 23 upstream of the two video cameras 2 for visible light. This is shown in Figure 7, where the Stokes vector components S0, S1, S2 can be measured without interfering with stereoscopic imaging.

[0077] In a digital surgical microscope, the Stokes parameters can also be measured using one or more polarization cameras that use small polarization filters on the camera pixels to realize the four measurements required to determine the Stokes vector. In that case, at least one of the four video cameras 2, 3 is a polarization camera 17. Preferably, one of the further video cameras 3 is also a polarization camera, as shown, for example, in FIG. 8. In this context, the polarization filtering arrangement 24 of FIG. 8 is optional. The principle of a polarization camera is shown in FIG. 9. Four pixels 16 arranged adjacently in a plane are each provided with a polarizer that is offset from each of the other polarizers.

[0078] For example, a polarization camera available from Sony Corporation has a resolution of 5 megapixels and a frame rate of 23 frames per second. This means that the time delay between two images is 43 ms, i.e., just below the required specification of 50 ms. In equation (1), the four polarizers are P0, P 45 , P 90 , P 135This corresponds to the first three Stokes parameters (S0, S1, S2) being measurable, but not the fourth component, S3. For tissue imaging in reflection, this limitation may be acceptable because the structural features are substantially linear, i.e., should primarily affect the linearly polarized component. For deep tissue imaging, it may be important that fiber layers lie obliquely on top of each other. This corresponds to combining linear retarders with different orientations, which can result in rotation and, therefore, circular birefringence. To measure all Stokes parameters, for example, a 0° quarter-wave retarder can be superimposed on the 135° or 45° polarizer of Figure 5. Combining these two results in a circular polarizer.

[0079] If the measurement of the Mueller matrix is ​​imperfect, the Chipman-Lou decomposition mentioned at the beginning is not possible. Furthermore, the essential goal of a surgical microscope with polarization contrast is not to measure the Mueller matrix perfectly and accurately, but instead to provide the user (e.g., surgeon) with good tissue contrast. Much analysis has been done in this regard in the past.

[0080] One variant is described in [6], where a set of parameters is defined that can be derived directly from the Mueller matrix coefficients, based on simulations of the polarization effects of isotropic and anisotropic tissues. Therefore, it is sufficient to measure a finite set of Mueller matrix coefficients and calculate the contrast derived from them. An example for this purpose from [6] is summarized in the table below.

[0081] [Table 1]

[0082] However, these are just some examples: there are even more significant combinations of Mueller matrix elements that can be used as image contrast for surgical microscopes.

[0083] The linear anisotropic media studied in [6], whose geometry closely resembles biological fibers, exhibit the following symmetry of the Mueller matrix:

number

[0084] Only a subset of 3x3 is different from zero and is symmetric, so there are only six independent components to be determined: I0, A, B, C, D, and E.

[0085] To measure a portion of the Mueller matrix, illumination with multiple polarization states, rather than just one, is required. An obvious solution would be to configure the filter 20 to be rotatable or to complement it with a ferroelectric liquid crystal filter. However, in this case, illumination with multiple polarization states can only be performed sequentially in time. Polarization imaging is already within the required specifications, and time-sequential polarized illumination would clearly exceed the requirement for a time delay of 50 ms or less for tissue contrast. If time cannot be used as a parameter to distinguish between the polarizations of illumination, it is possible within the scope of this invention to use the wavelength of the illumination light. Simultaneous illumination with two polarization states is possible by setting the two polarization states at different positions in the spectrum. In this case, spectral filters can also be used to reconstruct the associated images. This means that illumination must be set to different polarization states in two narrow spectral bands. If a "normal color impression" is still desired, unpolarized light or light of any desired polarization state must be present around the band (see Figure 3). Alternatively, dichromatic illumination is an option. For example, this can be achieved with two notch filters, as shown in Figure 10.

[0086] Figure 10 shows two schematic diagrams illustrating possible illuminations of an object space region. Both diagrams plot the intensity of illumination light I as a function of wavelength λ. The top diagram shows dichromatic illumination with a first wavelength range 31 and a second wavelength range 32, where the two wavelength ranges 31, 32 are polarized in opposite directions. The bottom diagram shows polychromatic illumination, where the two wavelength ranges 31, 32 are polarized in opposite directions, and the remaining spectral range 33 is unpolarized. For example, this can be achieved with two notch filters, as shown in Figure 11. In this case, two narrow-band polarized spectral components 31, 32 are achieved by passing unpolarized light through two narrow-band polarizing notch filters. To realize the concept shown in Figure 11, for example, polarizing bandpass filters can be used in reflection, as shown in Figure 12. Figure 12 shows the operating mode of the polarizing bandpass filter 34 from Semrock (https: / / www.semrock.com / a-new-class-of-polarization-optics-designed-specifically-for-lasers.aspx). On the left side, the beam paths for three different wavelengths λ1, λ2, and λ3 and their respective linear polarizations s and p are shown. In this case, s and p represent mutually orthogonal linear polarizations. On the right side of Figure 12, a plot of the transmission T through the filter 34 as a function of wavelength λ and polarizations s and p is shown.

[0087] Using the configuration shown in FIG. 13, the components of the Mueller matrix (e.g., M 00 , M 01 , M 10 , M 11 13, wavelengths or wavelength ranges λ1 and λ2 polarized perpendicularly to each other are illuminated and the individual polarized wavelengths are analyzed by different cameras, in the variant shown wavelength λ1 is analyzed by a first video camera for visible light (RGB camera) 2 and a first further video camera 3, and wavelength λ2 is analyzed by a second video camera for visible light (RGB camera) 2 and a second further video camera 3.

[0088] Of course, other configurations are possible, for example the RGB camera 2 can be replaced by a monochrome camera 3, or vice versa. However, without a polarization camera, in the variant shown in Figure 13, due to the spectral splitting, only two Stokes vector components S0 and S1 can be measured, instead of three or four. However, these could also be S0 and S2, in which case the Mueller matrix components M 00 , M 02 , M 20 , M 22 will be available.

[0089] In a variant shown in FIG. 14, two polarization cameras 17 are used as additional cameras 3, and two input polarizations can be used to measure half of the Mueller matrix, i.e., eight Mueller matrix elements. In this case, filter 20 (not plotted here) is a polarization notch filter that polarizes only two wavelengths, λ1 and λ2, in the unpolarized illumination spectrum. The remaining 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 take the form of a dichroic beam splitter, for example, for one wavelength with a first polarization and a second wavelength with a second polarization. This would be more efficient in terms of optical budget, but at the expense of flexibility. The advantage of this approach is that polarization becomes an additional option that does not interfere with standard imaging.

[0090] FIG. 15 illustrates a further embodiment of spectral encoding in which the spectral characteristics of the RGB channels of two color video cameras 2 are advantageously utilized. As described in connection with FIG. 14, filter 1 (not plotted here) in FIG. 15 is also a polarization notch filter, but here it is designed to be illuminated with four different wavelengths with defined, predefined polarizations. The polarizations of the different wavelengths may be different or partially identical. Video camera 2 (RGB camera) can be a one-chip or three-chip camera. In the case of a one-chip camera, a Bayer filter separates one sensor into three spectrally separated pixel arrays, while in the case of a three-chip camera, the signal can be spectrally split among three sensors using a splitter prism. The wavelengths of filter 20 in FIG. 15 are selected so that the RGB sensors detect the wavelengths separately and there is no crosstalk between the various wavelengths. This can be achieved, for example, by illuminating with wavelengths of 400 nm, 540 nm, and 680 nm, as illustrated by the typical spectral sensitivities of the RGB sensors and Bayer filters in FIG. 16. Figure 16 shows the relative spectral sensitivities of the splitter prism (top) and the Bayer filter (bottom) as a function of wavelength. The fourth wavelength of the illumination filter 20 is selected so that the two monochrome cameras 3 detect signals spectrally separated from the RGB camera 2. This can be achieved, for example, by illuminating with a wavelength in the infrared wavelength range (e.g., 800 nm), to which the RGB camera 2 is no longer sensitive. Naturally, it is also conceivable that the wavelengths are selected differently and that interfering wavelengths are removed upstream of the sensor by appropriate notch filters. Therefore, the filters 22 and 23 upstream of the RGB camera 2 are ideally designed as multi-bandpass filters for wavelengths of 400 nm, 540 nm, and 680 nm. At the same time, the filters 22 and 23 can be designed to differ in terms of their polarization properties. The filters 21 and 24 upstream of the further video camera (monochrome camera) 3 are designed as bandpass filters for a wavelength of 800 nm and, optionally, have similarly different polarization properties.

[0091] The exemplary embodiment of Fig. 15 describes a special case and can be generalized as follows: In a first step, the number N of detection channels present in the system is determined. In the example shown in Fig. 1, this is eight channels, with two further video cameras 3 (monochrome cameras) providing two channels and two additional visible light video cameras 2 (RGB cameras) providing six channels. The system is now designed so that these N detection channels provide optimal tissue contrast for each application. This is achieved by the fact that all N channels differ in at least one property (e.g., spectrum and / or polarization).

[0092] A first possible exemplary embodiment of a system with eight detection channels is illumination with eight different spectrally separated polarizations and detection with eight detectors analyzing in a spectrally separated manner with one polarization. A second possible exemplary embodiment of a system with eight detection channels is illumination with two defined spectrally separated polarizations and detection with eight detectors, in each case four detectors analyzing spectral regions with four different analyzers.

[0093] 17 shows a schematic diagram in the form of a flowchart of a method according to the present invention for generating an image representation (preferably a stereoscopic image representation) with polarization contrast of an object by means of the above-described visualization arrangement (e.g., the visualization arrangement of a surgical microscope) according to the present invention. The method includes, in step 41, illuminating the object with light waves by an illumination device, in step 42, capturing light waves emitted from the object after interaction of the illuminated light waves with the object by at least three video cameras or at least two polarization cameras, and in step 43, generating a preferably stereoscopic image representation with polarization contrast based on the generated polarization states of the illuminated light waves and / or the analyzed polarization states of the captured light waves. For specific embodiment variations of the method, please refer to the descriptions of FIGS. 1 to 16. [Explanation of symbols]

[0094] 1. Surgical microscope with visualization arrangement 2. Video camera 3. Video camera 4. Lighting Devices 5 Object area, object 6 Beam Path 7. Optical unit with variable focal length (varioscope) 8 Zoom optical unit 9 Video Objective Lenses 10 Laser autofocus device 11 Peripheral Camera 12 Beam splitter 13 Evaluation Device 14 (3D) Imaging Device 15 (Image) Data Transfer 16 pixels 17 Polarized Camera 19 Aperture element 20 Polarization Filtering Device 21 Polarization filtering device 22 Polarization filtering device 23 Polarization filtering device 24 Polarization Filtering Device 31 wavelength range 32 wavelength range 33 wavelength range 34 Polarizing Bandpass Filter 41 Irradiate light waves 42 Capture the light waves emitted from an object after the interaction of the irradiated light waves with the object 43. Generating an image representation with polarization contrast based on the generated polarization state of the illuminated light waves and / or the analyzed polarization state of the captured light waves. I strength T transmittance λ wavelength s Linearly polarized light p linearly polarized light P0 0 degree polarizer P90 90 degree polarizer P45 45 degree polarizer P135 135 degree polarizer PC circular polarizer PN neutral polarizer

Claims

1. A visualization arrangement (1) for microsurgery, comprising an imaging device (14), an illumination device (4) and a polarization determination arrangement, the polarization determination arrangement comprises at least two video cameras (2) and at least one further video camera (3) designed to capture light waves of a plurality of light wavelengths in the visible wavelength range, wherein an individual partial beam path of the beam path (6) is assigned to each of the three video cameras (2, 3), a plurality of polarization filtering devices (20-24), and an evaluation device (13), at least one polarizing 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); the polarizing filters (20-24) arranged in the beam path (6) upstream of the at least one designated further video camera (3) and the video camera (2) designed to capture light waves of a plurality of light wavelengths in the visible wavelength range are set or can be set to differ from one another in their polarizing effect, The evaluation device (13) is designed to generate an image representation with polarization contrast using the images captured by the video cameras (2, 3) and to display the image representation by means of the imaging device (14). A visualization arrangement (1) characterized in that:

2. The evaluation device (13) is designed to display the generated image representation with polarization contrast by the imaging device (14) over a white light image representation captured by at least two video cameras (2) designed to capture light waves of multiple light wavelengths within the visible wavelength range. A visualization arrangement (1) according to claim 1, characterized in that it

3. At least one polarization filtering device (20) is arranged in the beam path (6) downstream of the illumination device (4) and upstream of the object space region (5). A visualization arrangement (1) according to claim 1 or 2, characterized in that it

4. At least one of said polarization filtering devices (20-24) comprises a plurality of polarizers that are different from one another. A visualization arrangement (1) according to any one of claims 1 to 3, characterized in that

5. The at least one further video camera (3) is designed to capture monochrome light, or at least one of the video cameras (2, 3) takes the form of a polarized camera. A visualization arrangement (1) according to any one of claims 1 to 4, characterized in that it

6. At least one polarization filtering device (22, 23) arranged upstream of a video camera (2) designed to capture light waves of multiple light wavelengths in the visible wavelength range includes a circular polarizer. A visualization arrangement (1) according to claim 5, characterized in that it

7. The evaluation device (13) is designed to determine a set of Mueller matrix coefficients using the images captured by the video cameras (2, 3) and to determine the polarization contrast derived from the coefficients. A visualization arrangement (1) according to any one of claims 1 to 6, characterized in that it

8. A polarization filtering device (20) arranged in the beam path (6) downstream of the illumination device (4) and upstream of the object space region (5) is configured to simultaneously polarize at least two defined, mutually offset wavelengths in a mutually offset manner. A visualization arrangement (1) according to any one of claims 1 to 7, characterized in that it

9. At least one of said polarization filtering devices (20-24) comprises a wavelength filter and / or a wavelength selective polarizer A visualization arrangement (1) according to any one of claims 1 to 8, characterized in that

10. The lighting device (4) is designed to emit dichromatic light. A visualization arrangement (1) according to any one of claims 1 to 9, characterized in that

11. 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 the object space region (5) comprises at least one notch filter and / or a number of bandpass filters. A visualization arrangement (1) according to any one of claims 1 to 10, characterized in that it

12. A visualization arrangement (1) according to any one of claims 1 to 11, characterized by at least one beam splitter (12) arranged in the beam path (6) between an object space region (5) and the video camera (2, 3).

13. A visualization arrangement (1) for microsurgery, comprising an imaging device (14), an illumination device (4) and a polarization determination arrangement, the polarization determination arrangement comprises two polarization cameras (17), to each of which an individual partial beam path of the beam path (6) is assigned, and an evaluation device (13), The evaluation device (13) is designed to generate an image representation with polarization contrast using the image captured by the polarization camera (17) and to display the image representation by means of the imaging device (14). A visualization arrangement (1) characterized in that:

14. The evaluation device (13) is designed to display the generated image representation with polarization contrast by the imaging device (14) overlaying a white light image representation captured by the two polarization cameras (17). A visualization arrangement (1) according to claim 13, characterized in that it

15. A method for generating an image with polarization contrast of an object (5) by means of a microsurgical visualization arrangement (1) according to any one of claims 1 to 14, comprising: - irradiating (41) said object (5) with light waves by said illumination device (4); - capturing (42) by means of said at least three video cameras (2, 3) or said at least two polarization cameras (17) the light waves emitted by said object (5) after interaction of said irradiated light waves with said object (5); generating (43) an image representation with polarization contrast based on the generated polarization state of the irradiated light waves and / or the analyzed polarization state of the captured light waves; A method comprising:

16. 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) illuminate light waves with a defined polarization state.

16. The method of claim 15.

17. The polarization state of the received light waves is analyzed by the at least three video cameras (2, 3), the polarization filtering devices (21-24) arranged in the beam path (6) upstream of the video cameras, and / or by the polarization camera (17).

17. The method according to claim 15 or 16.

18. The evaluation device (13) is used to generate an image representation with polarization contrast based on the analyzed polarization state of the captured light waves, a set of Mueller matrix coefficients being determined by the images captured by the video camera (2, 3) and / or the polarization camera (17), and a polarization contrast derived from the coefficients being determined. The method according to any one of claims 15 to 17, characterized in that

19. The image representations with polarization contrast are generated within a time interval of less than 50 ms, and / or the resolution of the generated stereoscopic image representations with polarization contrast deviates by less than 10% from the resolution of corresponding image representations without polarization contrast. The method according to any one of claims 15 to 18, characterized in that

20. The image representation having polarization contrast is generated within a time interval of less than 50 ms and displayed over a multicolor image representation.

20. The method of claim 19.

21. A microscope comprising a visualization arrangement (1) according to any one of claims 1 to 14 or designed to carry out a method according to any one of claims 15 to 20.

Images