Illumination unit for an optical microscope and methods for its use

Abstract

The present invention relates firstly to an illumination unit for an optical microscope. The illumination unit serves to illuminate a sample to be examined under the microscope and comprises for this purpose a plurality of individual light sources (02). The illumination unit also comprises a plurality of light mixing elements (01), each having the form of a solid or hollow truncated pyramid with a base (03), a top surface (04), a lateral surface, and an axis. The individual light sources (02) are each arranged above the top surfaces (04) of the light mixing elements (01). The base surfaces (03) of the light mixing elements (01) together form a light emission surface (06) of the illumination unit. Furthermore, the invention relates to an optical microscope with the illumination unit according to the invention and to a method for using the microscope according to the invention.

Description

[0001] The present invention relates firstly to an illumination unit for an optical microscope. The illumination unit serves to illuminate a sample to be examined under the microscope and comprises a plurality of individual light sources for this purpose. Furthermore, the invention relates to an optical microscope with the illumination unit according to the invention and to a method for using the microscope according to the invention.

[0002] In digital microscopy, it is common practice to provide various illumination methods for quality assurance and quality control applications. Typical illumination methods include ring lighting, coaxial incident light, and transmitted light. Since most objects under investigation are not transparent, transmitted light serves to make objects visible as shadows against a bright background, allowing for the detection and measurement of their outer contours. Ring lighting typically provides diffuse illumination of the sample from various angles. In many applications, it is generated outside the observation aperture by ring-shaped LEDs and used with collector devices for efficient sample illumination.In non-telecentric observation, the light sources of the ring light can appear as bright reflections when viewing a flat, reflective sample. With telecentric observation, this effect does not occur with such samples, resulting in dark-field illumination. The ring light can be evenly distributed across the sample using collimation or homogenization elements, eliminating any visible inhomogeneities. Ring light assemblies are available in modular designs, either as attachments to the objective lens with additional cabling or as fixed components integrated into the objective lens or the microscope body.

[0003] In the case of non-flat samples, there can also be direct reflections from the ring light sources, which are imaged onto the camera of the digital microscope.

[0004] German patent DE 10 2015 208 080 A1 relates to a reflection correction method for correcting digital microscopic images. An object is illuminated with at least two illumination patterns. An illumination pattern image of the object is created for each illumination pattern. At least one partial reflection image is calculated from a combination of two corresponding illumination pattern images. A reflection-corrected image of the object is calculated from a combination of at least one illumination pattern image and at least one partial reflection image. Each illumination pattern has at least one active illumination source. The illumination patterns are distinct from one another.The term illumination pattern includes, in particular, lighting arrangements in which the sample is illuminated homogeneously and the pattern is formed only by selected angles of incidence; for example, by illumination from only one direction.

[0005] German patent applications DE 10 2015 208 087 A1 and US patent 10,620,417 B2 disclose a method for generating reflection-reduced contrast from microscopic images for reading height profile information about an object's surface. The method involves illuminating an object with an illumination sequence. An illumination image of the object is created for each illumination of the object in the sequence. A reflection-corrected illumination image is then determined for each illumination image. Two reflection-corrected illumination images adjacent with respect to the first axis are superimposed to form a first composite image of the first axis. Two reflection-corrected illumination images adjacent with respect to the second axis are superimposed to form a second composite image of the second axis. A first gradient image is created based on the first composite image. A second gradient image is created based on the second composite image.The first and second gradient images are transformed into a color space. A contrast image is then generated based on the transformed first and second gradient images within that color space.

[0006] From DE 10 2016 108 079 A1, an optical device with a sample holder is known, which is configured to fix an object in the beam path of the optical device. An illumination module of the optical device comprises several light sources and is configured to illuminate the object from multiple directions by operating the light sources. Each direction of illumination has an associated illuminating field. The optical device also includes a filter, which is arranged between the illumination module and the sample holder and is configured to widen the associated illuminating field for each direction of illumination. This is intended to reduce artifacts due to impurities during angle-selective illumination.

[0007] The aforementioned publications describe how a result image can be calculated using sequential image acquisition and corresponding sequential activation of parts of the ring illumination, in which reflections are reduced or even completely eliminated. Similarly, digital contrasts for examining the object can be achieved by activating only parts of the ring light for individual images, or, as in reflection correction, by using an algorithm to illuminate several images with individual light patterns and combine them into a single result image.

[0008] It is known in the art to reflect coaxial incident light into the beam path behind the objective lens, preferably into an infinity space. A homogeneous angular distribution is desirable because this translates into homogeneous field illumination via the objective lens. In digital microscopy, it is common for an optical zoom to enable different magnifications and numerical apertures for observing the object. Typically, the coaxial incident light is reflected between this zoom and the objective lens, as this is usually the location of the objective interface and thus also typically an infinity space. Without the use of an illumination zoom, the reflected coaxial incident light must provide all angles for the maximum field as well as the diameter for the maximum numerical aperture.Therefore, a complex lens arrangement is often chosen, in which a field diaphragm limits the angles of the illumination beam path at full aperture. Alternatively, the coaxial incident light illumination is reflected behind the zoom lens, but this has the disadvantage that every lens the coaxial incident light must pass through on its way to the object potentially generates internal reflections or reduces the light output. The latter is particularly true in the case of a polarization-based antireflection device. Furthermore, in the case of non-Köhler illumination, the ability to control the spatial distribution of the illumination in the objective pupil is severely limited.

[0009] Starting from the prior art, the object of the present invention is to be able to flexibly illuminate a sample for microscopic examination with different types of illumination without having to accept disadvantages such as unwanted reflections.

[0010] The aforementioned problem is solved by a lighting unit according to the attached claim 1, as well as by a microscope according to the attached dependent claim 8 and by a method according to the attached dependent claim 10.

[0011] The illumination unit according to the invention forms a component of an optical microscope and serves to illuminate a sample to be examined under the microscope. The illumination unit can form an integral part of the microscope or be designed as a module that can be exchanged on the microscope. The illumination unit emits light which strikes the sample, allowing the sample to be magnified and imaged using the microscope.

[0012] The illumination unit comprises a plurality of individual light sources for emitting light to illuminate the sample. The individual light sources are preferably arranged in a plane. The individual light sources are preferably arranged within an area, which is preferably circular. The individual light sources are preferably arranged in a matrix-like manner. Adjacent individual light sources are preferably equidistant from one another.

[0013] The lighting unit also includes a multitude of light mixing elements, each for mixing the light emitted by one of the individual light sources. Each light mixing element has the shape of a solid or hollow truncated pyramid with a base, a top, a lateral surface, and an axis. In the case of a hollow truncated pyramid, the top and base surfaces each have the form of a polygon with an inner polygonal cutout. The polygon and the polygonal cutout are preferably regular, geometrically similar, and concentric, and the polygon is preferably only slightly larger than the polygonal cutout. The mixing of the light from each individual light source takes place within the solid or hollow truncated pyramid. The individual light sources are arranged above the top surfaces of the light mixing elements.Insofar as the cover surfaces each have an inner cutout, the individual light sources are preferably arranged above the inner cutout of the respective cover surface. The individual light sources are preferably arranged as close as possible above the cover surfaces of the light mixing elements in order to couple as much light as possible from the respective individual light source into the light mixing element. The individual light sources are preferably located on the cover surfaces of the light mixing elements. Preferably, exactly one of the individual light sources is arranged above exactly one of the light mixing elements, above its cover surface. Preferably, exactly one of the individual light sources is located on exactly one of the light mixing elements, above its cover surface. The base surfaces of the light mixing elements together form a light-emitting surface of the lighting unit.The light from the individual light sources, mixed by the light mixing elements, emerges from the light emission surface and leaves the illumination unit to be used for illuminating the sample. The light emission surface is preferably flat. The base surfaces of the light mixing elements preferably form facets arranged in a parquet-like pattern to jointly form the light emission surface. Alternatively, the facets that together form the closed light emission surface are preferably arranged at the same position, scaled by a factor of less than one; for example, on a common transparent base plate. This can offer advantages when manufacturing the light mixing elements together as a monolithic component; for example, in an injection molding process using a transparent plastic. For this, a mold without tapered partition walls is required.

[0014] The light from each individual light source is reflected multiple times within the respective light mixing element, so that the angle between individual light rays emitted by the light source and the axis decreases with each reflection, resulting in a homogeneous distribution of the light exiting the light-emitting surface. Energy losses occur with every reflection of light at a reflective surface. Total internal reflection is an exception. The surfaces of the light mixing elements are preferably smooth, meaning they have such low roughness that no technically relevant scattering occurs. Such scattering would counteract the goal of light shaping and create uncontrollable light directions, as well as redistributing light energy. Since the light mixing elements each have the shape of a hollow truncated pyramid, this results in ideal entry and exit points.The inner walls of the hollow light mixing elements are preferably smooth and have a reflective coating.

[0015] A particular advantage of the lighting unit according to the invention is its suitability for flexibly generating different types and shapes of illumination. For example, the diameter of the luminous portion of the light-emitting surface can be changed by selecting the individual light sources to be operated. Different shapes, such as a ring light, can also be generated. Coaxial incident light can be produced. It is possible to switch flexibly between different lighting modes. The activation of the individual light sources in an azimuthal arrangement around the center of the light-emitting surface—for example, in propeller-like segments or hemispheres—is particularly beneficial to the aforementioned reflection reduction and digital contrast methods. Within such segments, radial selection between brightfield and darkfield is also possible.Restricting the azimuthal segments to individual radial rings can also be used to generate digital contrasts. The illumination can be implemented with or without a central light source.

[0016] A further particular advantage of the illumination unit according to the invention is that it can always be operated in such a way that the light emitted by the individual light sources is deflected by the light mixing elements so that each of the individual light sources emits only in directions that are captured by a lens of the microscope in the respective configuration and setting of the microscope. This ensures high efficiency of the illumination unit and avoids disturbing reflections, for example at lens edges inside the objective.

[0017] In preferred embodiments, the light mixing elements are each formed by a light mixing rod which has the shape of a solid truncated pyramid. In alternatively preferred embodiments, the light mixing elements are each formed by a hollow integrator which has the shape of a hollow truncated pyramid.

[0018] In preferred embodiments, the light mixing elements are identical. The light mixing elements preferably have the same shape. Likewise, the individual light sources are preferably identical. The individual light sources preferably have the same shape and the same properties with regard to light generation.

[0019] The truncated pyramids forming the shape of the light mixing elements are preferably straight, such that the base and top surfaces are each oriented perpendicular to their respective axes. The center of the base and the center of the top surface preferably lie on the axis of the respective truncated pyramid.

[0020] In preferred embodiments, the axes of the truncated pyramids forming the shape of the light mixing elements are arranged parallel to each other. The axes are preferably equidistant from one another.

[0021] In preferred embodiments, the base surfaces of the truncated pyramid-shaped light mixing elements each have the outer shape of a convex polygon, which is suitable for gapless tiling of the base surfaces. In preferred embodiments, the base surfaces of the truncated pyramid-shaped light mixing elements each have the outer shape of a triangle, a rectangle, or a regular polygon. Particularly preferably, the base surfaces of the truncated pyramid-shaped light mixing elements each have the outer shape of an equilateral triangle, a square, or a regular hexagon. The top surfaces preferably each have the same outer shape as the base surfaces, but are smaller. In principle, however, the light mixing elements can also have adaptation sections if the outer shape of the base surfaces differs from the shape of the top surfaces.

[0022] In preferred embodiments, the bases of the truncated pyramid-shaped light mixing elements completely fill the light-emitting surface of the lighting unit. This allows the light from the individual light sources to emerge homogeneously from the entire light-emitting surface. For this purpose, the identical bases each have a shape suitable for completely filling an area when joined together. This is the case, for example, with the shape of a regular hexagon, so that the light-emitting surface is filled in a honeycomb-like pattern by the bases of the light mixing elements. For manufacturing reasons, it can be advantageous to have webs between the bases.

[0023] In preferred embodiments, the truncated pyramid-shaped light mixing elements each have a termination region at their base surfaces, in which the lateral surfaces run perpendicular to the axis. In this respect, the termination regions represent a short extension of the truncated pyramid shape, in which the light mixing elements are no longer conical, thus facilitating the assembly of the light mixing elements for mounting the lighting unit. The lighting unit preferably comprises a frame in which the truncated pyramid-shaped light mixing elements are clamped at their termination regions and align themselves during assembly, thereby completely filling the light-emitting surface. In alternatively preferred embodiments, the truncated pyramid-shaped light mixing elements are attached to a base plate at their base surfaces, as is the case, for example, with a monolithic manufacturing method.

[0024] In preferred embodiments, at least three of the base surfaces of the light mixing elements touch at a single point along a central axis of the light-emitting surface. Thus, there is no single central light scale or single central light source. The central axis of the light-emitting surface is designed to lie along the optical axis of the microscope, so that, accordingly, there is no single central light scale or single central light source along the optical axis. This prevents any central direct reflection at lens vertices along the optical axis. With this embodiment, an integrated microscope illumination with brightfield incident light segments can be realized, which does not require any further antireflection measures, such as a polarizer or an analyzer.In alternative preferred embodiments, the base of exactly one of the light mixing elements is located centrally on a central axis of the light-emitting surface. Thus, there is a single average light scale or a single average light source.

[0025] The light mixing elements preferably consist of glass, quartz glass, or a transparent plastic. The cladding surfaces may have inwardly reflective surfaces.

[0026] The individual light sources are preferably each formed by an electric light source. The individual light sources are preferably each formed by an LED or another light-emitting semiconductor. Alternatively, fiber ends of a lighting fiber can be placed on the top surfaces of the light mixing elements. In further preferred embodiments, the spectral properties of the light emitted by the individual light sources are variable, for which the individual light sources are, for example, each formed by a four-color LED.

[0027] In preferred embodiments, the individual light sources are arranged as close as possible to the solid or cut-out surfaces of the light mixing elements. Accordingly, each individual light source is arranged with an air gap relative to the surface of the respective light mixing element, which is preferably less than 1 mm and more preferably less than 100 µm.

[0028] In preferred embodiments, the individual light sources each have a planar extension, with which they are arranged on the solid or cut-out surfaces of the light mixing elements and cover the surfaces completely. Thus, the individual light sources can emit their light completely onto the entire surface of the light mixing elements. If the individual light sources project beyond the surface of the light mixing elements on at least one side, the lighting unit preferably includes apertures that are arranged above the surface of the light mixing elements and prevent light from being emitted into the space between the light mixing elements.

[0029] In preferred embodiments, the lighting unit comprises at least 20 solid or hollow light mixing elements. In further preferred embodiments, the lighting unit comprises at least 40 solid or hollow light mixing elements. In further preferred embodiments, the lighting unit comprises at least 50 solid or hollow light mixing elements.

[0030] In preferred embodiments, the base surfaces of the light mixing elements are arranged evenly distributed around a central axis of the light emission surface within the light emission surface. The base surfaces of the light mixing elements are preferably enclosed by a circle within the light emission surface, the center of which lies on the central axis of the light emission surface.

[0031] The base surfaces of the light mixing elements each have a maximum dimension, preferably between 2 mm and 10 mm. The top surfaces of the light mixing elements each have a maximum dimension, preferably between 0.5 mm and 3 mm. The light mixing elements each have a height, preferably between 10 mm and 100 mm. The height is preferably at least ten times the maximum dimension of the base surface. Since the light mixing elements are preferably much taller than they are wide, and thus the deviation of the cross-section from a circular shape becomes negligible, their shape can be described as a cone to a first approximation.

[0032] The optical microscope according to the invention is used for microscopy of a sample. For this purpose, the microscope comprises an imaging optic for imaging the sample along a microscope beam path. The imaging optic preferably comprises at least one objective and preferably also a zoom optic and a tube lens. Furthermore, the microscope comprises the illumination unit according to the invention for illuminating the sample. The illumination unit is preferably optically coupled into the microscope beam path; for example, by reflecting the light exiting the light-emitting surface of the illumination unit into the microscope beam path.

[0033] In preferred embodiments, the microscope comprises a beam splitter, which is preferably arranged near an objective pupil of the imaging optics, and which divides the microscope beam path into an observation beam path and an illumination beam path. The beam splitter is preferably arranged shortly before or after the objective pupil of the imaging optics. The light-emitting surface of the illumination unit is located in the illumination beam path. The sample is viewed via the observation beam path. Either the observation beam path or the illumination beam path can lie on the axis of the microscope beam path. From the beam splitter onward, the illumination beam path and the observation beam path preferably run together along the optical axis of the imaging optics.The illumination beam path can be configured to have no, only partial, or complete overlap with the observation beam path. The illumination unit is preferably located in an infinite space.

[0034] The imaging optics preferably comprise a stereo lens or a lens with a larger pupil than required for microscopy of the sample. This allows for the creation of an internal darkfield. Alternatively, the method described below is preferably used to acquire multiple images under different illuminations. The multiple images are then combined to generate a high-contrast image that reveals similar properties of the sample as darkfield illumination.

[0035] The microscope preferably comprises one of the described preferred embodiments of the illumination unit according to the invention. Furthermore, the microscope preferably also has features which are specified in connection with the illumination unit according to the invention and its preferred embodiments.

[0036] The method according to the invention serves to utilize the optical microscope according to the invention. In one step of the method, a selection of individual light sources is determined according to a predetermined characteristic of the illumination of the sample to be achieved by the illumination unit. The selection of individual light sources preferably represents a true subset, so that the selection does not include all of the individual light sources. The characteristic of the illumination is determined by the type of illumination, such as incident light illumination or ring light illumination, and / or by dimensions, such as a diameter, and / or by photometric quantities, such as the illuminance, and / or by spectral properties. In a further step, the selected individual light sources are operated so that they emit light and illuminate the sample according to the predetermined characteristic of the illumination.

[0037] The method according to the invention utilizes the advantages of the illumination unit according to the invention. The sample can be flexibly illuminated with different types and shapes of illumination.

[0038] In a preferred embodiment, the selection of individual light sources includes those whose associated light mixing elements have their bases located radially within the observation pupil of the microscope. The radial direction is relative to an optical axis of the imaging optics. In an axial direction, i.e., along the optical axis of the imaging optics, any distance between the bases of the light mixing elements and the observation pupil can be disregarded in this embodiment. In this embodiment, the sample is illuminated with coaxial bright-field incident light illumination.

[0039] In a further preferred embodiment, the selection of individual light sources comprises those whose associated light mixing elements lie with their base surfaces in the radial direction outside an observation pupil of the microscope. This results in the sample being illuminated with coaxial dark-field illumination.

[0040] In a further preferred embodiment, the selection of individual light sources comprises those whose associated light mixing elements are located with their base surfaces in an off-center sub-segment of the light-emitting surface. This allows a selected section of the sample to be selectively illuminated.

[0041] In a preferred embodiment, the steps of determining a selection of individual light sources and operating the selected individual light sources are repeated to illuminate the sample according to a further predetermined illumination characteristic. This exploits the advantage of the invention to be able to switch quickly and efficiently between different types and modes of illumination.

[0042] In further preferred embodiments, the selection of individual light sources also includes specifics for their operation, such as reduced brightness, temporal behavior, or spectral properties of their emission. The individual light sources are then operated according to the selected specifications.

[0043] The method is preferably used for employing preferred embodiments of the microscope according to the invention.

[0044] Further details and developments of the invention will become apparent from the following description of preferred embodiments of the invention, with reference to the drawing. The drawing shows: Fig. 1: a perspective view of a preferred embodiment of a lighting unit according to the invention; Fig. 2: the in Fig. 1 Lighting unit shown in a front view; Fig. 3: a light mixing rod that is in Fig. 1 lighting unit shown in isolation; Fig. 4: the in Fig. 3 light mixing rod shown in a front view; Fig. 5: a schematic representation of a first preferred embodiment of a microscope according to the invention; Fig. 6: a schematic representation of a second preferred embodiment of the microscope according to the invention; and Fig. 7: another preferred embodiment of the lighting unit according to the invention.

[0045] Fig. Figure 1 shows a perspective view of a preferred embodiment of a lighting unit according to the invention. The lighting unit comprises a plurality of identical light mixing bars 01, which serve to align and homogenize light from a plurality of LEDs 02. The light mixing bars 01 each have the shape of a right truncated pyramid with a base 03 and a top surface 04. The base surfaces 03 and the top surfaces 04 each have the shape of a regular hexagon.

[0046] The light mixing bars 01 are arranged parallel and flush with each other, so that their base surfaces 03 form a planar surface, which constitutes a light emission surface 06 of the lighting unit. The truncated pyramid-shaped light mixing bars 01 each have a short end section 07 with parallel lateral surfaces on their base surfaces 01, which facilitates the planar assembly of the light mixing bars 01. The light mixing bars 01 are arranged such that their base surfaces 03 form the light emission surface 06 with a shape enclosed by a circle, so that the light emission surface 06 approximates a circular shape as closely as possible.

[0047] Fig. 2 shows the in Fig. 1. Lighting unit shown in a front view. In this front view, the light emission surface 06, which is formed in a parquet-like pattern by the base surfaces 03 of the light mixing bars 01 and has an approximately circular shape, can be seen. The base surfaces 03 of the light mixing bars 01 completely fill the light emission surface 06.

[0048] Fig. 3 shows one of the in Fig. Figure 1 shows the light mixing bars 01 in isolation in a side view. The dimensions of the light mixing bars 01 are particularly evident in this view.

[0049] Fig. 4 shows the one in Fig. Figure 3 shows a front view of the light mixing rod 01. The regular hexagonal shape of the base 03 is particularly noticeable.

[0050] Fig. Figure 5 shows a schematic representation of a first preferred embodiment of a microscope according to the invention. The microscope comprises an imaging optic 11 for optically imaging a sample 12. The object field diameter is, for example, 18 mm. Near an objective pupil 13, there is a beam splitter 14 for coupling out an observation beam path (not shown), while an illumination beam path (not shown) leads to infinity space, where an illumination coupling plane 16 is located, in which the light exit surface 06 (shown in Figure 5) is situated. Fig. 1) the lighting unit (shown in Fig. 1) is arranged. Alternatively, the illumination partial beam path (not shown) can be coupled with the beam splitter 14. Since the beam splitter 14 is arranged close to the objective pupil 13, the light from the illumination unit (shown in Fig. 1) reflected into the microscope beam path close to the objective pupil 13.

[0051] Fig. Figure 6 shows a schematic representation of a second preferred embodiment of the microscope according to the invention. This second embodiment initially resembles the one in Fig. 5. In contrast to the first embodiment, the beam splitter 14 is located between the objective pupil 13 and the imaging optics 11. The object field diameter is, for example, 44 mm. The illumination beam path (not shown) is coupled to the beam splitter 14.

[0052] Preferably, the microscope is assigned various objectives (not shown). With a balanced object distance, the objective pupil 13 is typically found at entirely different positions in infinity space. Therefore, the light exit surface 06 (shown in Fig. 1) the lighting unit (shown in Fig. 1) preferably positioned at a central position between the objective pupils 13 involved. This optimizes the illumination of the sample 12 with respect to field, homogeneity and reflection behavior in the imaging optics 11.

[0053] In the observation beam path (not shown), an observation pupil (not shown) is formed, which can also be variable along the optical axis by varying the zoom of the imaging optics 11. In any case, however, the diameter of the observation pupil (not shown) is variable in order to stabilize or appropriately limit the light transmittance in an intermediate image (not shown). This observation pupil (not shown) is projected onto the light exit surface 06 (shown in Fig. 1) the lighting unit (shown in Fig. 1), smaller than the light emission surface 06 (shown in Fig. 1), those of the LEDs 02 (shown in Fig. 1) not operated, whose associated light mixing bars 01 (shown in Fig. 1) with their base areas 03 (shown in Fig. 1) are hit by the observation pupil (not shown) and the remaining LEDs 02 (shown in Fig. 1) are operated. This allows for internal dark-field illumination or, in the case of only partial alignment of illumination patterns with the observation pupil (not shown), internal ring illumination. However, if those of LEDs 02 (shown in Fig. 1) operated, whose associated light mixing bars 01 (shown in Fig. 1) with their base areas 03 (shown in Fig. 1) When the zoom pupil (not shown) is struck, coaxial brightfield incident light illumination is achieved. The use of a zoom lens is not a limiting factor here. Likewise, the use of a fixed focal length tube lens is possible without the described limitations.

[0054] to lose lighting variants. To continuously switch between coaxial brightfield incident light illumination and darkfield or ring light illumination, only a brightness redistribution between the LEDs 02 (shown in Fig. 1) necessary. In the prior art solutions, the ring light or dark-field illumination and the coaxial incident light illumination are realized by different light sources, which, however, causes problems with setting the associated integration time and also with white balance if continuous switching is required. These problems do not occur in the solution according to the invention because of the large number of LEDs 02 (shown in Fig. 1) powered single light emission surface 06 (shown in Fig. 1) not on. By operating a selection of LEDs 02 (shown in Fig. 1) An illumination aperture diaphragm is not necessary, so the microscope preferably does not have such an illumination aperture diaphragm. The selection of LEDs 02 (shown in Fig. 1) can also be in the form of luminous hemispheres on the light-emitting surface 06 (shown in Fig. 1) or any other shapes or patterns. Alternatively, individual LEDs 02 (shown in Fig. 1) are selected and operated. The patterns are preferably further divided into light and dark field of observation depending on which of the base surfaces 03 (shown in Fig. 1) the projected observation pupil (not shown). This allows for a variety of illumination modes. Preferably, at least one microscopic image is captured with the microscope in each of these modes. From the microscopic images, various result images are preferably generated through common pixel operations. The pixel operations preferably include averaging.

[0055] In the event of reflections, the illumination is preferably segmented, for which a selection of LEDs 02 (shown in Fig. 1) is selected and operated, whose assigned light mixing bars 01 (shown in Fig. 1) with their base areas 03 (shown in Fig. 1) luminous segments on the light-emitting surface 06 (shown in Fig. 1) form. This also allows variations of these reflections to be generated, which can then be eliminated during subsequent image processing.

[0056] Fig. Figure 7 shows another preferred embodiment of the lighting unit according to the invention. This embodiment initially resembles the one shown in Fig. embodiment shown in 1. In contrast to the embodiment shown in Fig. In the embodiment shown in Figure 1, the light mixing bars 01 are formed monolithically with a base plate 18. In this respect, the light mixing bars 01 do not have a termination area 07 (shown in Figure 1). Fig. 1) on. Reference symbol list 01 Light mixing rod 02 LED 03 Base area 04 Cover area 05 - 06 Light emission area 07 Final Area 08 - 09 - 10 - 11 Imaging Optics 12 Sample 13 Objective pupil 14 beam splitters 15 - 16 Lighting coupling level 17 - 18 Base plate QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2015 208 080 A1

[0004] DE 10 2015 208 087 A1

[0005] US 10,620,417 B2

[0005] DE 10 2016 108 079 A1

[0006]

Claims

[1] Illumination unit for an optical microscope, comprising the following components: - a variety of individual light sources (02); and - a plurality of light mixing elements (01), each having the shape of a solid or hollow truncated pyramid with a base surface (03), a cover surface (03), a lateral surface and an axis, wherein the individual light sources (02) are each arranged above the cover surfaces (04) of the light mixing elements (01), and wherein the base surfaces (03) of the light mixing elements (01) together form a light exit surface (06) of the lighting unit. [2] Lighting unit according to claim 1, characterized by that the light mixing elements are each formed by a light mixing rod (01) with the shape of a full truncated pyramid or by a hollow integrator with the shape of a hollow truncated pyramid. [3] Lighting unit according to claim 1 or 2, characterized bythat the base surfaces (03) of the truncated pyramid-shaped light mixing elements (01) each have the outer shape of a convex polygon, which is suitable for a gapless parqueting of the base surfaces (03). [4] Lighting unit according to claim 3, characterized by that the base surfaces (03) of the truncated pyramid-shaped light mixing elements (01) each have the outer shape of an equilateral triangle, a square or a regular hexagon. [5] Lighting unit according to one of claims 1 to 4, characterized by that the base surfaces (03) of the truncated pyramid-shaped light mixing elements (01) completely fill the light exit surface (06) of the lighting unit. [6] Lighting unit according to one of claims 1 to 5, characterized by that the truncated pyramid-shaped light mixing elements (01) each have a terminal area (08) on their base surfaces (03), in which the lateral surfaces run perpendicular to the axis. [7] Lighting unit according to one of claims 1 to 6, characterized by that at least three of the base surfaces (03) of the light mixing elements (01) touch at one point in a central axis of the light exit surface (06), or that the base surface (03) of exactly one of the light mixing elements (01) is located centrally in a central axis of the light exit surface (06). [8] Optical microscope for microscopying a sample (12), comprising the following components: - an imaging optic (11) for imaging the sample (12); and - a lighting unit according to one of claims 1 to 7 for illuminating the sample (12). [9] Optical microscope according to claim 8, characterized bythat it comprises a beam splitter (14) which divides the microscope beam path into an observation partial beam path and an illumination partial beam path, wherein the light exit surface (06) of the illumination unit is arranged in the illumination partial beam path. [10] A method of using a microscope according to claim 8 or 9, comprising the following steps: - determining a selection of the individual light sources (02) according to a predetermined characteristic of an illumination of the sample (12) to be achieved by the illumination unit; and - Operating the selected individual light sources (02) to illuminate the sample (12) according to the specified illumination characteristics. [11] Method according to claim 10, characterized bythat the selection of the individual light sources (02) comprises those of the individual light sources (02) whose associated light mixing elements (01) lie with their base surfaces (03) in a radial direction in an observation pupil of the microscope in order to illuminate the sample (12) with a coaxial bright-field incident light illumination. [12] Method according to claim 10, characterized by that the selection of the individual light sources (02) comprises those of the individual light sources (02) whose associated light mixing elements (01) are located with their base surfaces (03) in a radial direction outside an observation pupil of the microscope in order to illuminate the sample (12) with a coaxial dark field illumination.

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