Illumination unit for optical microscope and method for using optical microscope

Abstract

The invention relates to an illumination unit for an optical microscope and a method for using an optical microscope. The illumination unit is used for illuminating a sample to be microexamined with a microscope and comprises a plurality of individual light sources (02) for this purpose. The lighting unit further comprises a plurality of light mixing elements (01), each of which has the shape of a solid or hollow truncated pyramid having a bottom surface (03), a top surface (04), a circumferential side surface and an axis. The individual light sources (02) are each arranged above the top surface (04) of the light mixing element (01). The bottom surfaces (03) of the light mixing elements (01) together form a light exit surface (06) of the lighting unit. The invention further relates to an optical microscope having an illumination unit according to the invention.

Description

Technical Field

[0001] The invention firstly relates to an illumination unit for an optical microscope. The illumination unit is used to illuminate a sample to be examined microscopically using a microscope and comprises a plurality of individual light sources for this purpose. In addition, the invention relates to an optical microscope having an illumination unit according to the invention and a method for using the microscope according to the invention. Background Art

[0002] In digital microscopy, it is common to provide different types of illumination for quality assurance and quality control. Typical types of illumination are ring light, coaxial incident light and transmitted light. Since most of the objects to be inspected are opaque, the transmitted light satisfies the function of making the object visible as a shadow in front of a bright background so that the outer contour can be identified and measured. Ring light usually meets the task of providing the sample with as diffuse an illumination as possible from different spatial angles. In many applications, the ring light is generated by an LED arranged in an annular manner outside the observation hole and is used together with the collecting device to effectively illuminate the sample. In non-telecentric observation, it may occur that when observing a flat reflective sample, the light source of the ring light can be directly identified as a bright reflection. In the case of telecentric observation, this effect does not occur in these samples, and dark field illumination is performed. The ring light can be evenly distributed on the sample using a collimating or homogenizing element, so that inhomogeneities can no longer be identified. The ring light arrangement is modularly implemented as being placed on an objective with additional wiring, or fixedly integrated into an objective or a microscope matrix.

[0003] In the case of non-flat samples, direct reflections can also be generated by means of a ring light source, which are imaged onto the camera of the digital microscope.

[0004] DE 10 2015 208 080 A1 relates to a reflection correction method for correcting digital microscopic images. An object is illuminated using 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 by combining two corresponding illumination pattern images. A reflection-corrected image of the object is calculated by combining 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 different from one another. The concept of illumination pattern also includes, in particular, an illumination arrangement in which the sample is uniformly illuminated and the pattern is formed only by selected angles of incidence, for example by illumination from only one orientation.

[0005] DE 10 2015 208 087 A1 and US 10,620,417 B2 show a method for forming a reflection-reduced contrast from a microscopic image for reading highly variable information of an object property. An object is illuminated using an illumination sequence. An illumination image of the object is created for each illumination of the object of the illumination sequence. A reflection-corrected illumination image is acquired for each illumination image. Two reflection-corrected illumination images adjacent to a first axis are superimposed to form a first full-axis image of the first axis. Two reflection-corrected illumination images adjacent to a second axis are superimposed to form a second full-axis image of the second axis. A first color change image is created based on the first full-axis image. A second color change image is created based on the second full-axis image. The first color change image and the second color change image are transformed into a color space. A contrast image is generated based on the first change image and the second change image transformed into the color space.

[0006] DE 10 2016 108 079 A1 discloses an optical device with a sample holder, which is designed to fix an object in the beam path of the optical device. The illumination module of the optical device includes a plurality of light sources and is designed to illuminate the object from a plurality of illumination directions by operating the light sources. Each illumination direction has an associated light field. The optical device also includes a filter, which is arranged between the illumination module and the sample holder and is designed to expand the associated light field for each illumination direction. As a result, artifacts due to contamination should be reduced in angle-selective illumination.

[0007] The aforementioned document describes how, with sequential image recording and corresponding sequential activation of parts of the ring lighting, a result image can be calculated in which reflections are reduced or even completely eliminated. Digital contrast for the object under examination can also be achieved by activating only parts of the ring lighting for each image or, as in the case of reflection correction, the algorithm also illuminates a plurality of images with individual light patterns, which are calculated to produce a result image.

[0008] It is known from the prior art that the coaxial incident light is reflected into the optical path behind the objective lens, preferably into infinite space. Here, it is sought to achieve an angular distribution as uniform as possible, because the angular distribution is converted into uniform field illumination by the objective lens. It is common in digital microscopy that optical zoom can achieve different magnifications and numerical apertures for observing objects. Usually, the coaxial incident light is reflected between this zoom and the objective lens, because this is usually where the objective lens interface is located, and therefore usually infinite space. In the case of not using illumination zoom, the reflected coaxial incident light must provide all angles of the maximum field and the diameter of the maximum numerical aperture. Therefore, an expensive lens arrangement is usually selected, in which the light field diaphragm for the illumination light path is limited to the angle under the full aperture. Alternatively, the coaxial incident light illumination is only reflected after the zoom, which has the disadvantage that each lens that the coaxial incident light must pass through on the path to the objective lens may produce internal reflections or reduce light emission. The latter is provided in particular in the case of polarization-based anti-reflection devices. Furthermore, in the case of non-Köhler illumination, the possibilities for controlling the positional distribution of the illumination in the objective pupil are severely restricted. Summary of the invention

[0009] Starting from this prior art, the object of the present invention is to enable flexible illumination of samples for microscopic examination using different types of illumination without having to accept disadvantages such as undesired reflections.

[0010] The stated object is achieved by an illumination unit according to the appended claim 1 and a microscope according to the appended claim 8 as well as a method according to the appended claim 10 .

[0011] The lighting unit according to the invention forms part of an optical microscope and is used to illuminate a sample to be examined microscopically with the microscope. The lighting unit can form an integral component of the microscope or be designed as a replaceable module on the microscope. The lighting unit emits light that reaches the sample, so that the sample can be imaged in an enlarged manner with the aid of the microscope.

[0012] The lighting unit comprises a plurality of single light sources for emitting light to illuminate the sample. The single light sources are preferably arranged in a manner distributed in a plane. The single light sources are preferably arranged in a manner distributed in a surface, and the surface preferably has a circular shape. The single light sources are preferably arranged in a matrix. Adjacent single light sources are preferably at equal distances from each other.

[0013] The lighting unit also includes a plurality of light mixing elements, which are respectively used to mix the light emitted by one of the single light sources. The light mixing elements respectively have the shape of a solid or hollow truncated pyramid, which has a bottom surface, a top surface, a peripheral side surface and an axis. In the case of a hollow truncated pyramid shape, the top surface and the bottom surface are respectively provided with a polygonal shape with an internal polygonal cutout, wherein the polygon and the polygonal cutout are preferably regular, geometrically similar and concentric, and wherein the polygon is preferably only slightly larger than the polygonal cutout. In the solid or hollow truncated pyramid shape, the light of the respective single light sources is respectively mixed. The single light sources are respectively arranged on the top surface of the light mixing element. As long as the top surface has an internal cutout, the single light sources are preferably respectively arranged on the internal cutout of the respective top surface. The single light sources are preferably respectively arranged as close as possible on the top surface of the light mixing element, so as to couple as much light as possible from the respective single light sources into the light mixing element. The single light sources are preferably respectively located on the top surface of the light mixing element. Preferably, exactly one of the single light sources is respectively arranged on its top surface on exactly one of the light mixing elements. Preferably, exactly one of the single light sources is located on exactly one of the light mixing elements on its top surface. The bottom surfaces of the light mixing elements together form the light exit surface of the lighting unit. The light of the single light sources mixed by the light mixing element is emitted from the light exit surface and leaves the lighting unit so that it can be used to illuminate the sample. The light exit surface is preferably flat. The bottom surface of the light mixing element preferably exhibits a close-packed arrangement of small planes that together form the light exit surface. Alternatively, however, the small planes that together form a closed light exit surface are preferably also arranged at the same position in a scaled manner with a factor less than 1; for example, they are arranged on a common transparent bottom plate. This can lead to advantages in the joint production of the light mixing element as an integral component; for example, in an injection molding method using transparent plastic. For this purpose, a casting tool without a tapering separation wall is required.

[0014] The light of each single light source is reflected multiple times in each light mixing element, so that the angle between each light beam emitted by the single light source and the axis becomes smaller with each reflection, thereby achieving a uniform distribution of the light emitted from the light exit surface. Each time the light is reflected on the reflective surface, energy loss will occur. The exception is total reflection. The surface of the light mixing element is preferably smooth, that is, the surface has a low roughness, so that technically relevant scattering no longer occurs. Scattering will violate the goal of light shaping and produce uncontrollable light directions and redistribute the light energy to these directions. As long as the light mixing elements have the shape of a hollow truncated pyramid, this leads to ideal injection and ideal emission. The inner walls of the hollow light mixing elements are preferably smooth and have a reflective coating.

[0015] The particular advantage of the lighting unit according to the invention is that it is suitable for flexibly producing different types of lighting and lighting shapes. By selecting the single light sources to be operated respectively, for example, the diameter of the luminous part of the light exit surface can be changed. Different shapes, such as ring light, can also be produced. Coaxial incident light can be produced. It is possible to switch flexibly between different types of lighting. In particular, activating the single light source in the azimuth selection around the center of the light exit surface, for example in a propeller-like segment or hemisphere, is also conducive to the above-mentioned reflection reduction and digital contrast methods. Within these segments, it is also possible to choose between bright field and dark field in the radial direction. Limiting the azimuth segments to individual radial rings can also be used to generate digital contrast. The lighting can be implemented with or without an intermediate single light source.

[0016] A further particular advantage of the lighting unit according to the invention is that the lighting unit can always be operated in such a way that the light emitted by the operating individual light sources is deflected by the light mixing element, so that each operating individual light source emits only in the direction that is received by the objective of the microscope in the respective configuration and setting of the microscope. This ensures a high efficiency of the lighting unit and avoids disruptive reflections, for example at the inner lens edges of the objective.

[0017] In a preferred embodiment, the light mixing elements are each formed by a light mixing rod having the shape of a solid truncated pyramid. In an alternative preferred embodiment, the light mixing elements are each formed by a hollow integrator having the shape of a hollow truncated pyramid.

[0018] In a preferred embodiment, the light mixing elements are designed identically. The light mixing elements preferably have the same shape. Likewise, the individual light sources are preferably designed identically. The individual light sources preferably have the same shape and the same properties with respect to the generation of light.

[0019] The shape of the truncated pyramid forming the light mixing element is preferably straight, so that the bottom surface and the top surface are respectively oriented perpendicular to the respective axis. The center point of the bottom surface and the center point of the top surface are preferably located on the axis of the respective truncated pyramid.

[0020] In a preferred embodiment, the axes of the truncated pyramids forming the shape of the light mixing element are arranged in parallel. The axes are preferably arranged equidistant from one another.

[0021] In a preferred embodiment, the bottom surface of the truncated pyramid light mixing element has a convex polygonal shape, which is suitable for seamless tiling of the bottom surface. In a preferred embodiment, the bottom surface of the truncated pyramid light mixing element has a triangular, rectangular or regular polygonal shape. Particularly preferably, the bottom surface of the truncated pyramid light mixing element has an equilateral triangle, a square or a regular hexagonal shape. The top surface preferably has the same shape as the bottom surface, but it is smaller. In principle, if the shape of the bottom surface is different from the shape of the top surface, the light mixing element can also have a matching section.

[0022] In a preferred embodiment, the bottom surface of the truncated pyramid-shaped light mixing element completely fills the light exit surface of the lighting unit. As a result, the light of a single light source can be emitted uniformly from the entire light exit surface. For this purpose, the same bottom surfaces each have a shape suitable for completely filling the surface by joining together. This is the case, for example, in the shape of a regular hexagon, so that the light exit surface is filled in a honeycomb shape by the bottom surface of the light mixing element. For manufacturing reasons, it may be advantageous to form a connection between the bottom surfaces.

[0023] In a preferred embodiment, the truncated pyramid-shaped light mixing elements each have an end region at their bottom surface, in which the lateral surface extends parallel to the axis of the truncated pyramid. In this respect, the end region represents a short extension of the truncated pyramid shape, in which the light mixing element is no longer conically formed, which facilitates the splicing of the light mixing elements for mounting the lighting unit. The lighting unit preferably comprises a frame, into which the truncated pyramid-shaped light mixing elements are clamped at their end regions and aligned during mounting and thus completely fill the light exit surface. In an alternative preferred embodiment, the truncated pyramid-shaped light mixing element is fastened with its bottom surface to a base plate, which is produced, for example, by an integral manufacturing method.

[0024] In a preferred embodiment, at least three of the bottom surfaces of the light mixing element touch at one point on the central axis of the light exit surface. Therefore, there is no single intermediate light scale or a single intermediate single light source. The central axis of the light exit surface is arranged to be located in the optical axis of the microscope, so that there is no single intermediate light scale or a single intermediate single light source in the optical axis. As a result, no central direct reflection is generated on the lens vertex on the optical axis. With this embodiment, integrated microscope illumination can be achieved with a bright field incident light segment, which does not require additional anti-reflection measures, such as polarizers or analyzers. In an alternative preferred embodiment, the bottom surface of exactly one light mixing element is located centrally on the central axis of the light exit surface. Therefore, there is a single intermediate light scale or a single intermediate single light source.

[0025] The light mixing element is preferably made of glass, quartz glass or transparent plastic. The lateral surface can have an inwardly reflecting surface.

[0026] The single light sources are preferably formed by electric light sources. The single light sources are preferably formed by LEDs or other light-emitting semiconductors. However, the fiber ends of the illumination fibers can also be placed on the top surface of the light mixing element. In a further preferred embodiment, the light emitted by the single light sources is variable in its spectral characteristics, for which purpose the single light sources are formed, for example, by 4-color LEDs.

[0027] In a preferred embodiment, the single light sources are arranged as close as possible on the solid or cut-out top surface of the light mixing element. Therefore, the single light sources are arranged facing the top surface of the respective light mixing element with a certain air gap, which is preferably less than 1 mm, and further preferably less than 100 μm.

[0028] In a preferred embodiment, the single light sources each have a planar extension, with which they are arranged on a solid or cut-out top surface of the light mixing element and respectively cover the top surface. The single light sources can thus emit their light completely into the entire top surface of the light mixing element. If the single light sources protrude beyond the top surface of the light mixing element on at least one side, the lighting unit preferably comprises a stop, which is respectively arranged above the top surface of the light mixing element and prevents light from being emitted into the space between the light mixing elements.

[0029] In a preferred embodiment, the lighting unit comprises at least 20 solid or hollow light mixing elements therein. In another preferred embodiment, the lighting unit comprises at least 40 solid or hollow light mixing elements therein. In another preferred embodiment, the lighting unit comprises at least 50 solid or hollow light mixing elements therein.

[0030] In a preferred embodiment, the bottom surface of the light mixing element is evenly distributed around the center axis of the light exit surface in the light exit surface. The bottom surface of the light mixing element is preferably enclosed by a circle in the light exit surface, the center point of the circle is located on the center axis of the light exit surface.

[0031] The bottom surface of the light mixing element has a maximum extension of preferably between 2 mm and 10 mm. The top surface of the light mixing element has a maximum extension of preferably between 0.5 mm and 3 mm. The light mixing element has a height of preferably between 10 mm and 100 mm. The height is preferably at least ten times greater than the maximum extension of the bottom surface. Since the light mixing element is preferably much taller than it is wide and therefore deviations of the cross section from a circular shape become insignificant, its shape can be described as a cone in a first approximation.

[0032] The optical microscope according to the invention is used for microscopic examination of samples. For this purpose, the microscope comprises an imaging optical device for imaging the sample along the microscope beam path. The imaging optical device preferably comprises at least one objective lens and preferably also a zoom optical device and a tube lens. In addition, the microscope comprises an illumination unit according to the invention for illuminating the sample. The illumination unit is preferably optically coupled into the microscope beam path, for example, in such a way that light emitted from a light exit surface of the illumination unit is reflected into the microscope beam path.

[0033] In a preferred embodiment, the microscope includes a beam splitter, which is preferably arranged near the objective pupil of the imaging optical device and divides the microscope light path into an observation sub-light path and an illumination sub-light path. The beam splitter is preferably arranged not far before or after the objective pupil of the imaging optical device. The light exit surface of the illumination unit is arranged in the illumination sub-light path. The sample is observed by the observation sub-light path. The observation sub-light path or the illumination sub-light path can be located on the axis of the microscope light path. Starting from the beam splitter, the illumination sub-light path and the observation sub-light path preferably extend together along the optical axis of the imaging optical device. However, the illumination sub-light path can be configured so that the illumination sub-light path does not have an overlap with the observation sub-light path or has a partial or complete overlap with the observation sub-light path. The illumination unit is preferably located in an infinite space.

[0034] The imaging optics preferably comprise a stereo objective or an objective with a larger pupil than is required for microscopic examination of the sample. Thus, an internal dark field can be achieved. Alternatively, preferably, the following method is applied to record multiple images in different illuminations. The multiple images are then calculated to produce a high-contrast image that shows properties of the sample similar to those of dark field illumination.

[0035] Preferably, the microscope comprises one of the described preferred embodiments of the illumination unit according to the invention. Furthermore, the microscope preferably also has the features described in conjunction with the illumination unit according to the invention and its preferred embodiments.

[0036] The method according to the invention is used for using the optical microscope according to the invention. In the steps of the method, the selection of a single light source is determined according to the preset characteristics of the illumination of the sample obtained by the illumination unit. The selection of a single light source preferably represents a real subset, so that the selection does not include all single light sources. The illumination characteristics are determined by the type of illumination, such as incident light illumination or annular light illumination, and / or by size, such as diameter, and / or by photometric parameters, such as illumination intensity, and / or by spectral characteristics. In a further step, the selected single light source is operated so that it emits light and illuminates the sample according to the preset illumination characteristics.

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

[0038] In a preferred embodiment, the selection of single light sources includes the following single light sources: the light mixing elements assigned to these single light sources are located with their bottom surface in the observation pupil of the microscope in the radial direction. The radial direction is related to the optical axis of the imaging optical system. In this embodiment, in the axial direction, that is, in the direction of the optical axis of the imaging optical system, the possible distance between the bottom surface of the light mixing element and the observation pupil can be ignored. In this embodiment, the sample is illuminated by coaxial bright field incident light illumination.

[0039] In another preferred embodiment, the selection of single light sources includes the following single light sources: the light mixing elements assigned to these single light sources are located with their bottom surfaces outside the observation pupil of the microscope in the radial direction. Thus, the sample is illuminated by coaxial dark field illumination.

[0040] In another preferred embodiment, the selection of single light sources includes the following single light sources: the light mixing elements assigned to these single light sources are located with their bottom surfaces in discrete subsections of the light exit surface. As a result, selected sections of the sample can be illuminated in a targeted manner.

[0041] In a preferred embodiment, the steps of determining the selection of a single light source and operating the selected single light source are repeated so as to illuminate the sample according to another preset illumination characteristic. Thus, the advantage of the present invention of being able to switch quickly and effectively between different illumination types and illumination shapes is fully utilized.

[0042] In another preferred embodiment, the selection of the single light source also includes the specifications of its operation, such as the reduction of brightness, the time characteristics or the spectral characteristics of its emission. The single light source operates according to the selected specifications.

[0043] The method is preferably used in a preferred embodiment using the microscope according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Further details and improvements of the present invention are obtained from the following description of preferred embodiments of the present invention with reference to the accompanying drawings. In which:

[0045] Figure 1 A perspective view showing a preferred embodiment of a lighting unit according to the present invention;

[0046] Figure 2 Shown in front view Figure 1 The lighting unit shown;

[0047] Figure 3 Shown separately Figure 1 The light mixing rod of the lighting unit shown;

[0048] Figure 4 Shown in front view Figure 3 The light mixing rod shown;

[0049] Figure 5 A schematic diagram showing a preferred first embodiment of the microscope according to the present invention;

[0050] Figure 6 A schematic diagram showing a preferred second embodiment of the microscope according to the present invention; and

[0051] Figure 7 Further preferred embodiments of the lighting unit according to the invention are shown. DETAILED DESCRIPTION

[0052] Figure 1 A perspective view of a preferred embodiment of a lighting unit according to the present invention is shown. The lighting unit comprises a plurality of identical light mixing rods 01, which are used to orient and homogenize light from a plurality of LEDs 02. The light mixing rods 01 each have the shape of a right truncated pyramid having a bottom surface 03 and a top surface 04. The bottom surface 03 and the top surface 04 each have the shape of a regular hexagon.

[0053] The light mixing rods 01 are arranged parallel to each other and flush, so that their bottom surfaces 03 are closely packed to form a flat surface, which is a light exit surface 06 of the lighting unit. The truncated pyramid-shaped light mixing rods 01 have short end regions 07 at their bottom surfaces 03, respectively, and the end regions have parallel peripheral sides, thereby facilitating the closely packed splicing of the light mixing rods 01. The light mixing rods 01 are arranged so that their bottom surfaces 03 form a light exit surface 06 having a shape enveloped by a circle, so that the light exit surface 06 has a circular shape as close as possible.

[0054] Figure 2 Shown in front view Figure 1 The lighting unit shown. In this front view, the light exit surface 06 formed by the bottom surface 03 of the light mixing rod 01 in a close-packed manner can be seen, and the light exit surface 06 has an approximately circular shape. The bottom surface 03 of the light mixing rod 01 completely fills the light exit surface 06.

[0055] Figure 3 Shown separately in side view Figure 1 The light mixing rod 01 is shown. In this view, the extension of the light mixing rod 01 can be seen in particular.

[0056] Figure 4 Shown in front view Figure 3 The light mixing rod 01 shown is particularly recognizable in the regular hexagonal shape of the base 03 .

[0057] Figure 5The schematic diagram of a preferred first embodiment of a microscope according to the invention is shown. The microscope comprises an imaging optical device 11 for optical imaging of a sample 12. For example, the object field diameter is 18 mm. A beam splitter 14 is located near the objective pupil 13 for decoupling the observation sub-path (not shown), while the illumination sub-path (not shown) is guided in infinite space, in which the illumination coupling plane 16 is located, and the illumination unit (in Figure 1 The light exit surface 06 (shown in Figure 1 Alternatively, the illumination sub-path (not shown) can be coupled in using a beam splitter 14. Since the beam splitter 14 is located near the objective pupil 13, the illumination unit (in Figure 1 The light (shown in FIG) is reflected near the objective pupil 13 into the microscope optical path.

[0058] Figure 6 The schematic diagram of a preferred second embodiment of the microscope according to the present invention is shown. Figure 5 The embodiment shown is identical. In contrast to the first embodiment, a beam splitter 14 is located between the objective pupil 13 and the imaging optics 11 . The object field diameter is 44 mm, for example. An illumination sub-beam path (not shown) is coupled in using the beam splitter 14 .

[0059] Preferably, the microscope is equipped with various different objective lenses (not shown). In the case of the adjusted object distance, the objective lens pupil 13 can usually be located at completely different positions in infinite space. Therefore, the illumination unit (in Figure 1 The light exit surface 06 (shown in Figure 1 ) is preferably positioned at an intermediate position between the relevant objective pupils 13. As a result, the illumination of the sample 12 is optimized with respect to the field, homogeneity and reflection properties in the imaging optical device 11.

[0060] An observation pupil (not shown) is formed in the observation beam path (not shown), which observation pupil can also vary along the optical axis as the zoom of the imaging optical device 11 changes. However, in any case, the diameter of the observation pupil (not shown) is variable in order to stabilize or appropriately limit the light guide value in the intermediate image (not shown). Figure 1 The light exit surface 06 (shown in Figure 1 The observation pupil (not shown) is smaller than the light exit surface 06 (shown in Figure 1 ), then LED 02 (in Figure 1 ) whose associated light mixing rods 01 (in Figure 1 ) with its bottom surface 03 (in Figure 1 The LEDs that touch the observation pupil (not shown) are not operated, while the remaining LEDs 02 (in Figure 1 Thus, internal dark field illumination can be achieved, or, in the case where the illumination pattern only partially coincides with the observation pupil (not shown), inner ring illumination can be achieved. In contrast, if LED 02 (in Figure 1 ) whose associated light mixing rods 01 (in Figure 1 shown) with its bottom surface 03 (in Figure 1 If the LED 02 (shown in FIG. 1 ) is operated against a zoom pupil (not shown), then coaxial bright field incident light illumination is achieved. The use of zoom should not be understood as restrictive. Likewise, a tube lens with a fixed focal length can be used without losing the illumination variant described. In order to switch continuously between coaxial bright field incident light illumination and dark field or ring light illumination, it is only necessary to switch between LED 02 (shown in FIG. 1 ). Figure 1 In the solutions known from the prior art, the ring light or dark field illumination and the coaxial incident light illumination are realized by different light sources, but this also causes problems in setting the relevant integration times and in the white balance when switching continuously. These problems are solved in the solution according to the invention by using a plurality of LEDs 02 (in Figure 1 ) supplies the only light exit surface 06 (in Figure 1 By selecting LED 02 (in Figure 1 ) does not require an illumination aperture diaphragm, so the microscope preferably does not have such an illumination aperture diaphragm. Figure 1 The choice of light exit surface 06 (shown in Figure 1 Alternatively, individual LEDs 02 (shown in FIG. 1 ) may be selected and operated in the form of a light emitting hemisphere or any other shape or pattern. Figure 1 According to which of the bottom surfaces 03 (in Figure 1 ), the pattern is preferably again divided into a bright field and a dark field for observation. Thus, various illumination modes can be realized. Preferably, in each of these modes, at least one microscopic image is recorded with the microscope. Preferably, different result images are generated from the microscopic images by a common pixel operation. The pixel operation preferably includes average value formation.

[0061] In the event of reflections, it is preferred to split the illumination, for which the following LEDs 02 (in Figure 1 ) are shown in the selection: the light mixing bar 01 assigned to these LEDs (in Figure 1 ) with its bottom surface 03 (in Figure 1 ) at the light exit surface 06 (in Figure 1As a result, changes in reflections can also be produced, which can be eliminated within the scope of subsequent image processing.

[0062] Figure 7 Another preferred embodiment of the lighting unit according to the present invention is shown. Figure 1 The same as shown in the embodiment. Figure 1 Unlike the embodiment shown, the light mixing rod 01 is formed integrally with the base plate 18. In this respect, the light mixing rod 01 does not have an end region 07 (at Figure 1 ).

[0063] Reference numerals list

[0064] 01 Light Mixing Stick

[0065] 02 LED

[0066] 03 Bottom

[0067] 04 Top

[0068] 05 -

[0069] 06 Light exit surface

[0070] 07 End Zone

[0071] 08 -

[0072] 09 -

[0073] 10 -

[0074] 11 Imaging Optics

[0075] 12 samples

[0076] 13 Objective pupil

[0077] 14 Beam splitter

[0078] 15 -

[0079] 16 Illumination coupling plane

[0080] 17 -

[0081] 18 Base Plate

Claims

1. An illumination unit for an optical microscope, the illumination unit comprising the following components: - Multiple single light sources (02); and - A plurality of light mixing elements (01), each of which has the shape of a solid or hollow truncated pyramid, wherein the truncated pyramid has a bottom surface (03), a top surface (04), a peripheral side surface and an axis, wherein the single light sources (02) are respectively arranged on the top surfaces (04) of the light mixing elements (01), and wherein the bottom surfaces (03) of the light mixing elements (01) jointly form a light exit surface (06) of the lighting unit.

2. The lighting unit according to claim 1, characterized in that: The light mixing elements are formed by light mixing rods (01) having the shape of a solid truncated pyramid or by hollow integrators having the shape of a hollow truncated pyramid.

3. The lighting unit according to claim 1, characterized in that: The bottom surfaces (03) of the truncated pyramid-shaped light mixing elements (01) each have a convex polygonal shape, and the convex polygon is suitable for seamless tiling of the bottom surface (03).

4. The lighting unit according to claim 3, characterized in that: The bottom surface (03) of the truncated pyramid-shaped light mixing element (01) has an equilateral triangle, a square or a regular hexagonal shape.

5. The lighting unit according to claim 1, characterized in that: The bottom surface (03) of the truncated pyramid-shaped light mixing element (01) completely fills the light exit surface (06) of the lighting unit.

6. The lighting unit according to claim 1, characterized in that: The truncated pyramid-shaped light mixing elements (01) each have an end region (07) on their base (03), in which the lateral surface extends parallel to the axis of the truncated pyramid.

7. The lighting unit according to claim 1, characterized in that: At least three bottom surfaces (03) of the light mixing element (01) are in contact at one point on the central axis of the light exit surface (06), or exactly one bottom surface (03) of the light mixing element (01) is centrally located on the central axis of the light exit surface (06).

8. An optical microscope for microscopic examination of a sample (12), the optical microscope comprising the following components: - an imaging optical device (11) for imaging the sample (12); and - An illumination unit according to any one of claims 1 to 7, for illuminating the sample (12).

9. The optical microscope according to claim 8, characterized in that The optical microscope comprises a beam splitter (14), which splits the microscope light path into an observation sub-light path and an illumination sub-light path, wherein the light exit surface (06) of the illumination unit is arranged in the illumination sub-light path.

10. A method for using a microscope according to claim 8 or 9, comprising the steps of: - determining the selection of the single light source (02) according to predetermined characteristics of the illumination of the sample (12) obtained by the illumination unit; and - operating the selected single light source (02) so as to illuminate the sample (12) according to preset characteristics of the illumination.

11. The method according to claim 10, characterized in that The selection of single light sources (02) includes the following single light sources (02): the light mixing elements (01) assigned to these single light sources are located with their bottom surfaces (03) in the radial direction in the observation pupil of the microscope in order to illuminate the sample (12) with coaxial bright field incident light illumination.

12. The method according to claim 10, characterized in that The selection of single light sources (02) includes the following single light sources (02): the light mixing elements (01) assigned to these single light sources are located with their bottom surfaces (03) outside the observation pupil of the microscope in the radial direction in order to illuminate the sample (12) with coaxial dark field illumination.

Images