Method and apparatus for adjusting and controlling parameters of an illumination area of ​​an ophthalmic device - Patents.com

Abstract

The present invention relates to a solution for adjusting and controlling parameters of an illumination area of ​​an ophthalmic device. The parameters can be, for example, brightness, color / color temperature, area shape, polarization state, etc. The device according to the invention comprises an actuation unit for adjusting desired illumination parameters, an illumination unit for generating illumination radiation with the desired illumination parameters, a separation element for separating a portion of the illumination radiation, a sensor element for analyzing the separated portion of the illumination radiation, and an evaluation unit for evaluating the sensor data and determining the actual illumination parameters of the illumination radiation. According to the present invention, the sensor element is a spatially resolved image sensor. The proposed solution is provided in particular for adjusting and controlling parameters of an illumination area of ​​an ophthalmic device, but can also be applied in other technical fields, such as microscopy.

Description

[Technical field]

[0001] The present invention relates to a method and apparatus for adjusting and controlling parameters of an illumination field of an ophthalmic device. By way of example, brightness, color / color temperature, field shape, polarization state, etc. may be considered as parameters in this context. [Background technology]

[0002] The parameters of the illumination field in laser-based applications are typically controlled by analyzing an out-coupled defined portion of the radiation. The shape of the wavefront in the optical system is monitored in the same way according to known prior art techniques: a defined small fraction of the monitored radiation is coupled out and recorded and evaluated by a dedicated sensor (e.g. a Shack-Hartmann sensor). Again, the information obtained can be used to influence the wavefront in a targeted way.

[0003] In contrast to this, the parameters of the illumination fields of ophthalmic devices such as slit lamps, fundus cameras, etc. have so far not been set at all, not set at all, or only indirectly via calibrated scales on the operating elements.

[0004] There is no control over the resulting light distribution in the actual illumination field, in terms of brightness or color, or in terms of the position, width and height of slits etc. The location of the operating elements is usually determined from ergonomic considerations, so that said operating elements are often not in the immediate vicinity of the affected assembly. However, the path for transmitting the operating settings may be subject to errors, and therefore it is not possible to exclude mismatches between the scale settings and the resulting light distribution characteristics, especially after the device has been in use for a relatively long period of time.

[0005] To allow repeated adjustment of the operating elements, some ophthalmic devices are equipped with a unitless scale, so that at least approximately the same settings can be reproducibly applied at different times. However, the drawback here is that the settings are made on the operating elements without actually knowing which corresponding parameters of the illumination field are actually set.

[0006] In modern ophthalmic devices, it is becoming increasingly important to have information about the actual parameters used in the illumination field also available in electronic form, for example for their documentation and / or to enable their use in control loops. Furthermore, the availability of this information in electronic form makes it available to the user on the eyepiece or display, which can significantly improve the workflow, since all relevant information can be made available while maintaining their position relative to the device.

[0007] Furthermore, the electronic availability of such parameter information opens up the possibility of using this as (meta)information in automated further processing, such as image processing, deep learning or other artificial intelligence methods.

[0008] The availability of the actually used parameters of the illumination field in electronic form is particularly important in relation to the aspect of remote controlled use of ophthalmic diagnostic devices (also known under the term telemedicine), in which an external operator is entirely dependent on reliable feedback regarding the current device configuration, and in particular the actual parameters of the illumination field.

[0009] In this regard, WO 2013 / 081619 A1 describes a system for ophthalmic imaging. The solution is based on an ophthalmic device that is controlled via a network and records stereoscopic or three-dimensional images. The system can then be remotely accessed by one or more physicians to dynamically control all aspects of the ophthalmic device in real time via the network and to verbally interact with the patient. The recorded three-dimensional images of the patient's eye are transmitted in real time to the physician, who can thus perform an eye examination on at least a portion of the eye. As the ophthalmic device is controlled in real time via the network, the physician can vary and refine the images to optimize the examination. Using the system of the invention, a comprehensive eye examination can be performed remotely in detail and with clarity, as if the physician was in the same location as the patient.

[0010] Both the importance and the desire to use such device parameters to be able to generate benefits or added value for the user can be gleaned from various citations in the prior art.

[0011] Known solutions describe the use of a wide variety of lighting parameters to be made available to the user as an aid in the operation of an ophthalmic device. For example, the eye is illuminated with a slit aperture to perform magnified observation of the entire anterior segment, the cornea, the sclera, the iris, the lens, the conjunctiva, the eye chamber, the angle, the vitreous humor, and the retina using a slit lamp microscope. There are also various observation techniques using a slit lamp microscope. These include different illumination and image recording methods. By way of example, illumination can be performed diffusely, directly and tangentially, or as background illumination. As imaging methods, fluorescent staining photography, photography using a gonioscopic or fixed lens are widely used. It should be noted that within the scope of examination using a slit lamp microscope, any combination of observation objects and observation techniques can be applied.

[0012] In slit lamp examination, depending on the selected observation object and / or observation technique, it is necessary to appropriately adapt the settings of the optical system, such as the illumination angle, the amount of illumination light, the observation magnification, the slit width, the filters, and the settings of the image recording system, such as the light sensitivity, the shutter speed, the aperture value, etc. Only in this way is it possible to perform optimal image capture and examination with minimal burden on the doctor and the patient.

[0013] However, it is difficult to appropriately set or change the settings of the optical system and imaging system according to various combinations of observation objects and / or observation techniques, especially when a doctor has little experience using a slit lamp microscope for examination purposes.

[0014] In this regard, US Patent Application Publication No. 2014 / 0139807 describes a slit lamp microscope whose optical system settings can be easily adapted to various conditions.

[0015] For this purpose, the slit lamp microscope has a storage unit configured to store correspondence information that associates default setting conditions of the illumination system and / or the observation system with each of a plurality of parts of the eye. The default setting conditions include, for example, the value of the observation magnification, the slit width, the light amount, the irradiation angle, the presence or absence of irradiation of background illumination light, the presence or absence of a diffusion element, an aperture, or a filter in the optical path, etc.

[0016] After the region of the eye to be examined is determined, the default setting conditions of the region are retrieved from the corresponding information and compared with the current setting state previously detected, and setting states different from the retrieved default setting conditions are found. The different setting states are output to the display unit so that they can be corrected accordingly. However, the described solution seems to use data in the form of default setting conditions more often, since the extraction of the data is only very vaguely indicated. [Prior art documents] [Patent documents]

[0017] [Patent Document 1] International Publication No. 2013 / 081619 [Patent Document 2] US Patent Application Publication No. 2014 / 0139807 Summary of the Invention

[0018] According to the known prior art, such data are obtained with the help of various sensors. In this case, axially coupled potentiometers are particularly frequently used to detect rotational or translational movements. Other possible sensors are based on detecting changes in the properties of resonant circuits, capacitance, Hall effect, etc.

[0019] The dynamic range and value range required for such a sensor represents a particular challenge: for example, in the case of a slit lamp microscope, if one wishes to set a slit width between 100 μm and 20 mm, one needs to determine the slit width with an accuracy better than 25 μm.

[0020] Mechanical changes in the position of the diffusing element, diaphragm or filter need to be determined in order to detect their presence or absence in the light path, which is often very difficult given the small installation space.

[0021] For space reasons, it may be necessary to place the sensor not directly on the component that affects the light field parameters, but somewhere along the control chain between the actuator (e.g., a rotating knob, a sliding element, etc.) and that component. This introduces systematic and random deviations, hysteresis, and other errors that can only be partially compensated for by a calibration process.

[0022] Also, a drawback of the known systems is that different sensors, including signal and supply lines and evaluation electronics, are required to determine very different parameters of the illumination field.

[0023] In addition to solving the installation space problem, it is also necessary to ensure that the various transducers and / or sensors do not affect each other, or that changes in one of the transducers are actually only detected by the associated sensor.

[0024] The latter is particularly problematic when several assemblies, e.g. in the case of a slit lamp microscope, have a large number of parameters to be set and therefore also have multiple transducers, sensors, connecting lines, etc., which must be moved relative to the housing.

[0025] The present invention is based on the objective of overcoming the drawbacks of the solutions known from the prior art and of developing a solution for setting and controlling a large number of parameters of the illumination and / or observation field of an ophthalmic device, which solution does so using as few sensors as possible and, in the process, minimizes the susceptibility of said sensors to disturbances and mutual interference.

[0026] In a method for setting and controlling parameters of an illumination field of an ophthalmic device, in which desired illumination parameters are set, illumination radiation is generated using the desired illumination parameters and converted into a light distribution in a focal plane, a portion of the illumination radiation is output coupled and directed to a sensor element for analysis purposes, and actual illumination parameters of the illumination radiation are determined from the sensor data, this objective is achieved by using a spatially resolved image sensor as a sensor element for analyzing the output coupled portion of the illumination radiation.

[0027] Possible spatially resolving image sensors can be based, for example, on CMOS or CCD technology, although other technologies are conceivable in the future. According to a first preferred embodiment, the out-coupled portion of the radiation reflects the real light distribution and changes the real light distribution as little as possible. The image sensor of the digital camera records the image data continuously or sequentially, utilizing the dynamic range of the image sensor.

[0028] According to a second preferred embodiment, the image data recorded by the image sensor is checked for its validity in a first step. The calibration values ​​are used to determine the parameters from the recorded image data, and the ascertained actual illumination parameters are then provided to the user or user-available software as numerical and / or graphical representations and presented on a display or in the viewing beam path.

[0029] The proposed solution is intended in particular for setting and controlling the parameters of the illumination field of ophthalmic devices, but can also be used in other technical fields, such as, for example, microscopy.

[0030] The invention is explained in more detail below on the basis of exemplary embodiments. [Brief description of the drawings]

[0031] [Figure 1] FIG. 1 shows a schematic diagram in the form of a flow chart of the steps of a method according to the invention. [Diagram 2] FIG. 2 shows a schematic diagram of the device according to the invention using the example of a slit lamp. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0032] In the proposed method for setting and controlling the parameters of the illumination field of an ophthalmic device, desired illumination parameters are set, illumination radiation is generated with the desired illumination parameters and converted into a light distribution in a focal plane, a portion of the illumination radiation is coupled out and directed to a sensor element for analysis purposes, and the actual illumination parameters of the illumination radiation are determined from the sensor data. According to the invention, a spatially resolved image sensor is used as a sensor element for analyzing the coupled out portion of the illumination radiation. In this case, the geometric resolution of the sensor can be adapted to the accuracy required by the application. As a result, it is also possible to use very cost-effective sensors for lower sensor resolution, such as sensors comparable to those of optical mice (computer input devices).

[0033] Particularly preferably, a spatially resolving image sensor of a camera is used. In this case, the illumination parameters are specified in the form of information by the system or by a user and are set such that a desired light distribution is produced at the focal plane.

[0034] According to the present solution, illumination parameters such as, for example, brightness, color, light field shape, polarization, etc. are used to generate a desired light distribution. In this case, the brightness of the light distribution can be set and optionally modified by varying the current or voltage in the light source(s), and the color or color temperature of the light can be set and optionally modified using filters or by combining light sources of different colors and their targeted amplification or attenuation.

[0035] The field shape of the light distribution can be changed by apertures, DMDs, ELCoS, etc., but a polarizer is required to change its polarization. What is important for the invention is that the out-coupled part of the radiation actually reflects the real light distribution and that as little as possible of the real light distribution is changed as a result of the out-coupling.

[0036] If the out-coupled beam changes, this must be taken into account when determining the actual illumination parameters of the illumination radiation. In order to do this, however, the effect of this change must be known. This can be determined, for example, during the manufacturing process in the form of a calibration, and the specific parameters can be stored in the module and thus kept available for further use.

[0037] According to an advantageous embodiment of the method according to the invention, the image data is recorded continuously or sequentially by a spatially resolved image sensor. In this case, the dynamic range of the image sensor can be particularly advantageously utilized and can be used as a light output detector. For this purpose, particular attention is paid to ensuring that the individual pixels are not overdriven or that the dynamic range of the camera used is utilized. For this purpose, the pixels with the highest intensity are selected and the camera parameters, for example the exposure time or the gain, are set via an algorithm (for example a binary search) so that these pixels take on a value just below the upper dynamic range.

[0038] As a result, there are no longer any overdriven or underdriven pixels in the entire image and all of the data can be used for further analysis. In this case, these camera settings can also be used as parameters later on.

[0039] The image data recorded by the spatially resolved image sensor is analyzed and parameters are determined therefrom using adapted and / or optimized algorithms. In a first step, the validity of the recorded image data can be checked.

[0040] For this purpose, the image data is examined using an algorithm to determine whether there are one or more illuminated fields in the camera image. Only a single illuminated field is expected. If more than one is detected, the system may not be optimally configured. In that case, the subsequent algorithm steps will not necessarily be effective either. Ideally, the user should be informed of this.

[0041] The image data recorded by the spatially resolved image sensor is then used to determine the parameters using adapted and / or optimized algorithms. To determine the parameters, a calibration value is used, for example a one-time comparison of size, angle and color representation between the image field and the analysis results of the image sensor.

[0042] To determine the width, length and orientation of the slit, the illuminated field and its edges are detected using an algorithm from the image data recorded by the image sensor. In this case, the distance between two parallel edges corresponds to the width of the slit, and the perpendicular distance corresponds to the height of the slit. The centerline between the two detected edges represents the reference for the rotation angle evaluation of the slit position.

[0043] The colour of the illuminated field can be inferred from the intensities of different coloured sub-images of the image data recorded by the image sensor. Typically, only a small number of filters are used in an ophthalmic device, so the assignment of the light distribution detected by the sensor to the filters in use is not of much concern: a filter-dependent histogram of the corresponding light distribution can be stored in the sensor within the adjustment / calibration process.

[0044] After image processing algorithms are used to determine whether one or more of the desired parameters are set correctly, the confirmed actual lighting parameters of the illumination emission are stored for documentation and / or reproduction purposes.

[0045] In particular, parameters determined from the recorded images and their size may be stored as meta-information about the recorded images or used as input variables for a control loop of the lighting module.

[0046] According to a further advantageous embodiment of the method according to the invention, the actual lighting parameters are made available to the user as numerical and / or graphical representations. This may be implemented, for example, on a display or in the direct viewing beam path.

[0047] In this regard, FIG. 1 shows in the form of a flow chart a possible sequence of steps of the method according to the invention. After the desired illumination parameters have been set and the illumination radiation has been generated using the corresponding illumination parameters, a portion of the generated light distribution is coupled out and analyzed to determine therefrom the actual illumination parameters of the illumination radiation.

[0048] For this purpose, images are recorded by a spatially resolved image sensor, checked for plausibility and, if not plausible, repeated while adjusting the image recording parameters if necessary. Illuminated fields are detected from plausible image data, likewise checked for plausibility and, if not plausible, repeated and the user can receive feedback thereon.

[0049] In a first step, the edges of the slit image representation are detected from the plausible illuminated field, their dimensions are determined and preferably displayed to the user. For this purpose, calibration data can additionally be used.

[0050] In a second step, the rotation angle of the slit image representation is determined and preferably also displayed to the user. In this case, the center line between the two detected long edges represents a reference for evaluating the rotation angle. For this purpose, calibration data can also be used in addition.

[0051] In a third step, the intensities are determined and the color of the illuminated field is estimated from the intensities of the different colored sub-images. At the same time, after a corresponding calibration, the intensity of the light source can be estimated from the intensity measured for a given exposure time of the camera.

[0052] The proposed device for setting and controlling parameters of an illumination field of an ophthalmic device comprises an actuation unit for setting desired illumination parameters, an illumination unit for generating illumination radiation with the desired illumination parameters, an out-coupling element for coupling out a portion of the illumination radiation, a sensor element for analyzing the out-coupled portion of the illumination radiation, and an evaluation unit for evaluating the sensor data and determining the actual illumination parameters of the illumination radiation. According to the invention, the sensor element for analyzing the out-coupled portion of the illumination radiation is a spatially resolved image sensor which can record both intensity and information in a spatially resolved manner.

[0053] According to a first advantageous embodiment of the device according to the invention, the sensor element is a spatially resolving image sensor of a camera. To be able to evaluate the color information, the image sensor must have components with different spectral responses. For example, the BAYER matrix filters present in many cameras are also suitable for this purpose.

[0054] According to an advantageous embodiment of the device according to the invention, the lighting unit comprises a plurality of spectrally distinct and separately controllable light sources, and furthermore the lighting unit has a variable iris in order to increase the dynamic range.

[0055] As already mentioned above, lighting parameters such as, for example, brightness, color, light field shape, polarization, etc. are used to generate a desired light distribution. In this case, the brightness of the light distribution can be set and optionally modified by changing the current or voltage in the light source(s), and the color or color temperature of the light can be set and optionally modified with filters or by combining light sources of different colors and their targeted amplification or attenuation. The field shape of the light distribution can be changed by diaphragms, DMDs, ELCoS, etc.

[0056] In order to be able to determine the parameters of the actual light distribution, a portion of the radiation that actually reflects the real light distribution is coupled out. A beam splitter provided for this purpose transmits this portion of the radiation for analysis purposes to a spatially resolved image sensor that serves as a sensor element.

[0057] However, the output coupling elements for output coupling a portion of the illumination radiation may also be existing elements in the form of mirrors or prisms, with their optically active surface designed as a partially transparent layer rather than a reflective optical layer.

[0058] As already explained, the spatially resolved image sensor is designed to continuously or sequentially record image data and transmit said image data to an evaluation unit for its evaluation and for determining the actual illumination parameters of the illumination radiation.

[0059] The evaluation unit includes a microprocessor for analysing the images recorded by the image sensor and for determining the actual illumination parameters of the illumination radiation. The microprocessor analyzes the recorded image data and determines the parameters and their size by using adapted / optimized algorithms. For this purpose, it is preferable to use calibration values ​​that compare once, for example, size, angle and color representation between the set desired illumination parameters and the image data recorded by the image sensor and characterizing the actual light distribution in the focal plane.

[0060] The device according to the invention may comprise a storage unit for documenting and / or reproducing actual lighting parameters of the illumination radiation, whereby the ascertained actual lighting parameters of the illumination radiation may be stored as input variables of a control loop of the lighting unit or as meta-information of the recorded image data.

[0061] In particular, this can attract the user's attention. For this purpose, the device can be equipped with elements for the numerical and / or graphical representation of the actual lighting parameters. The numerical and / or graphical representation can be implemented on a display or directly in the observation beam path, for which purpose the device is provided with elements for input coupling into the observation beam path.

[0062] In this respect, Fig. 2 shows a schematic diagram of the device according to the invention using the example of a slit lamp. In an exemplary manner desired illumination parameters 2 are set on an actuation unit 1 in order to generate a corresponding illumination radiation distribution in a focal plane 5 by means of an illumination unit 3 and a slit generating unit 4 (shown in a simplified manner).

[0063] A beam splitter 6 is used to couple out a portion of the illumination radiation, which is imaged onto a spatially resolved image sensor 7 for the purpose of analysing the illumination radiation. A microprocessor 8 evaluates the sensor data transmitted from the spatially resolved image sensor 7 and combines said sensor data by calculation with any existing calibration data, thereby determining actual illumination parameters of the illumination radiation, which are presented on a display 9.

[0064] According to a further advantageous embodiment of the device according to the invention, the device comprises an additional sensor element for a polarization-dependent analysis of the outcoupled portion of the illumination radiation, which is the only way in which polarization-dependent properties can be detected.

[0065] For this purpose, for example, a Stokes setup can be used, in which at least four different polarization states (parallel or serial) are generated and measured, and the polarization state of the radiation is then back-calculated from these.

[0066] A further embodiment relates to a camera that includes a spatially resolving image sensor. An advantageous embodiment provides that the camera observing the real image field is equipped with specific algorithms for analysing and evaluating the lighting information from the overall image.

[0067] Furthermore, it is advantageous if the camera used to record the image information is equipped with specific algorithms for analysing and evaluating the lighting information from the overall image. The solution according to the invention provides a method and an apparatus for setting and controlling the parameters of the illumination field of an ophthalmic device, thereby correcting the drawbacks of the solutions known from the prior art. The proposed solution makes it possible to set and control a large number of parameters of the illumination and / or observation field of an ophthalmic device while minimizing the susceptibility of sensors to disturbances and mutual interference in the process.

[0068] The fact that the solution allows multiple parameters to be recorded and analyzed simultaneously using only one sensor is particularly advantageous. The use of a camera image sensor also has the advantage that the overall construction can be significantly miniaturized.

Claims

1. A method for setting and controlling parameters of an illumination field of an ophthalmic device, in which desired illumination parameters are set, illumination radiation is generated using the desired illumination parameters and converted into a light distribution in a focal plane, a portion of the illumination radiation is coupled out and directed to a sensor element for analysis purposes, and actual illumination parameters of the illumination radiation are determined from sensor data, characterized in that a spatially resolved image sensor is used as the sensor element for analyzing the coupled out portion of the illumination radiation.

2. 2. The method of claim 1, characterized in that the spatially resolved image sensor of a camera is used.

3. 10. The method of claim 1, wherein illumination parameters including at least one of brightness, color, light field shape, and polarization can be used to generate a desired light distribution.

4. The method of claim 1 , wherein the desired lighting parameters are specified by a system or a user.

5. 2. The method according to claim 1, characterized in that the outcoupled portion of the illumination radiation reflects a real light distribution and changes the real light distribution as little as possible.

6. 10. The method of claim 1, wherein the spatially resolved image sensor of a digital camera records image data continuously or sequentially.

7. 2. The method of claim 1, wherein the dynamic range of the spatially resolved image sensor is utilized.

8. 10. The method of claim 1 or 6, characterized in that the dynamic range of the spatially resolved image sensor is used as a light power detector.

9. 2. The method of claim 1, characterized in that images recorded by the spatially resolved image sensor are analyzed and the parameters are determined using adapted and / or optimized algorithms.

10. 10. A method according to claim 1 or 9, characterized in that the image data recorded by the spatially resolved image sensor are checked for their validity in a first step.

11. 10. The method according to claim 1 or 9, characterized in that a calibration value is used to determine said parameter.

12. 10. A method according to claim 1 or 9, characterized in that in the image data recorded by the spatially resolved image sensor, the illuminated field and its edges are detected and the width, length and orientation of the slit are determined therefrom.

13. 10. A method according to claim 1 or 9, characterized in that the colour of the illuminated field is deduced from the intensities of differently coloured partial images in the image data recorded by the spatially resolved image sensor.

14. 10. The method according to claim 1 or 9, characterized in that an image processing algorithm is used to detect whether one or more of the desired lighting parameters are correctly set in the image data recorded by the spatially resolved image sensor.

15. 2. The method according to claim 1, characterized in that the actual lighting parameters of the illumination radiation are stored for documentation and / or reproduction purposes.

16. 2. A method according to claim 1, characterized in that the parameters determined from the recorded images and their size are stored as meta-information or are used as input variables for a control loop of the lighting module.

17. 2. The method of claim 1, characterized in that the actual lighting parameters are made available to the user as numerical and / or graphical representations.

18. 20. The method according to claim 1 or 17, characterized in that the numerical and / or graphical representations of the actual illumination parameters are presented on a display or coupled into a viewing beam path.

19. An apparatus for setting and controlling parameters of an illumination field of an ophthalmic device, comprising an operating unit for setting desired illumination parameters, an illumination unit for generating illumination radiation using the desired illumination parameters, an output coupling element for output coupling a portion of the illumination radiation, a sensor element for analyzing the output coupled portion of the illumination radiation, and an evaluation unit for evaluating sensor data to determine actual illumination parameters of the illumination radiation, characterized in that the sensor element for analyzing the output coupled portion of the illumination radiation is a spatially resolved image sensor.

20. 20. The apparatus of claim 19, wherein the sensor element is the spatially resolved image sensor of a camera.

21. 20. The apparatus of claim 19, wherein the illumination unit includes a variable aperture for increasing its dynamic range.

22. 20. The apparatus of claim 19, wherein the illumination unit comprises a plurality of spectrally distinct and separately controllable light sources.

23. 20. The apparatus of claim 19, wherein the output coupling element for output coupling a portion of the illumination radiation is a beam splitter.

24. 20. The device according to claim 19, characterized in that the output coupling element for output coupling a portion of the illumination radiation is an existing element in the form of a mirror or a prism and has an optically active surface designed as a partially transparent layer rather than a reflective optical layer.

25. 20. The device according to claim 19, characterized in that the evaluation unit comprises a microprocessor for analyzing the images recorded by the spatially resolved image sensor and for determining actual illumination parameters of the illumination radiation.

26. 20. Apparatus according to claim 19, characterized in that a storage unit is present for recording and / or reproducing the actual illumination parameters of the illumination radiation.

27. 20. Apparatus according to claim 19, characterized in that an element for numerical and / or graphical representation of the actual lighting parameters is present.

28. 28. Apparatus according to claim 19 or 27, characterized in that an element is present for coupling the numerical and / or graphical representation of the actual illumination parameters into the observation beam path.

29. 20. The device according to claim 19, characterized in that a sensor element is also present for a polarization-dependent analysis of the outcoupled portion of the illumination radiation.

30. 20. Apparatus according to claim 19, characterized in that the camera observing the real image field is equipped with specific algorithms for analysing and evaluating the lighting information from the overall image.

31. 20. Apparatus according to claim 19, characterized in that the camera used for recording the image information is equipped with specific algorithms for analysing and evaluating the lighting information from the overall image.

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