DIGITAL MICROSCOPE AND METHOD OF OPERATING A DIGITAL MICROSCOPE

A digital microscope includes: a stage for holding a sample; a monochrome digital camera; an optical system, arranged between the stage and the monochrome digital camera; an illumination assembly for illuminating the sample; and a control unit for controlling the monochrome digital camera and the illumination assembly; wherein the illumination assembly is configured to provide illumination with three different wavelength ranges, and wherein the control unit is configured to control the illumination assembly to sequentially provide illumination with the three wavelength ranges and wherein the control unit is configured to control the monochrome digital camera to take separate images during illumination with the three wavelength ranges.

BACKGROUND OF THE INVENTION

1. Technical Field

The present invention is in the field of digital microscopy. In particular, the present invention is in the field of the overall system set-up of a digital microscope.

2. Background Information

Conventional digital microscopes have an illumination assembly, in operation emitting white light, a stage for holding a sample, an optical system, having microscope objective and a tube objective, and a color digital camera. In operation, the illumination assembly illuminates the sample on the stage by directing light through the sample and to the optical system towards the digital camera. The digital camera takes color images of the sample. Given the magnification of the optical system and the desire to detect/examine very small structures/features in the sample, the resolution of digital cameras, as currently used in digital microscopes, is not always satisfactory. Also, current set-ups of digital microscopes tend to be very costly.

Accordingly, it would be beneficial to provide a digital microscope with an overall system design that allows for a high image resolution/high representation accuracy at a reasonable cost/reasonable system complexity. Also, it would be beneficial to provide an according method of operating a digital microscope.

SUMMARY OF THE INVENTION

Exemplary embodiments of the invention include a digital microscope, comprising: a stage for holding a sample; a monochrome digital camera; an optical system, arranged between the stage and the monochrome digital camera; an illumination assembly for illuminating the sample; and a control unit for controlling the monochrome digital camera and the illumination assembly; wherein the illumination assembly is configured to provide illumination with three different wavelength ranges, and wherein the control unit is configured to control the illumination assembly to sequentially provide illumination with the three wavelength ranges and wherein the control unit is configured to control the monochrome digital camera to take separate images during illumination with the three wavelength ranges.

Exemplary embodiments of the invention allow for the provision of digital microscopic images at a high resolution/representation accuracy. As compared to previous approaches, the digital microscope in accordance with exemplary embodiments of the invention is able to provide digital color images, without relying on a color camera. Common color cameras are so-called Bayer filter cameras, relying on a color filter matrix, having red, blue and green filter pieces and being arranged before the image sensor, for generating the color representation of the sample. By design, the color filter pieces are offset from each other, with said offset posing a limitation to the achievable resolution/representation accuracy. Also, in said Bayer filter cameras, the extension of 2×2 color filter pieces and of the associated sensor cells limits the size of a single image pixel, posing another limitation for the achievable resolution/representation accuracy. In exemplary embodiments of the invention, instead of offsetting three representations of a sample in space, as has been previously done with a Bayer filter camera, the three representations of the sample are staggered in time. The three different wavelength ranges provide a sequence of three different modes of illumination. No spatial shift between different representations of the sample is present on the camera side of the digital microscope, and a very high integration density of real image pixels in the camera can be achieved. Also, the need for a comparably expensive color camera may be eliminated. Further, as compared to so-called three-chip cameras, a single image sensor can be used and light splitting before the image sensors can be dispensed with. A particularly beneficial trade-off between high resolution/representation accuracy and reasonable cost/complexity of implementation may be achieved.

The digital microscope may also be referred to as digital light microscope. In particular, the digital microscope may be a transmitted light microscope, with the illumination assembly and the monochrome digital camera being arranged on opposite sides of the stage/sample. In an operation position of the digital microscope, the illumination assembly may shine light upwards from a lower portion of the digital microscope towards the stage/sample and towards the optical system and monochrome digital camera.

The illumination assembly is configured to provide illumination with three wavelength ranges. The illumination assembly may be switchable between providing illumination with the three different wavelength ranges. In other words, the illumination assembly may be operable to selectively provide illumination with any of the three wavelength ranges. The switching between the three different wavelength ranges/the selective provision of illumination with the three different wavelength ranges may be controlled by the control unit. The control unit may control every single switch between the wavelength ranges or may control by triggering a predefined illumination pattern or may perform any other suitable control for achieving a time-selective illumination with the three different wavelength ranges. The expression of the illumination assembly being configured to provide illumination with three different wavelength ranges is understood as the illumination assembly being configured to provide illumination with at least three different wavelength ranges. It is also possible that the illumination assembly is configured to provide illumination with four or five or six or more different wavelength ranges.

The control unit is configured to control the illumination assembly to sequentially provide illumination with the three wavelength ranges and is configured to control the monochrome digital camera to take separate images during illumination of the stage with the three wavelength ranges. In operation, the control unit may provide illumination of the sample, arranged on the stage, with each of the three wavelength ranges in sequence. Further, the control unit may control the monochrome digital camera to take a sequence of separate images during illumination of the sample, with the separate images corresponding to the instances of illumination with the different wavelength ranges. The control unit is configured to provide a synchronized illumination and acquisition of digital image data. Via the synchronized control of the illumination assembly and the monochrome digital camera, the provision of illumination with a particular one of the three different wavelength ranges is accompanied by the taking of a particular image in the sequence of images. The control unit may be seen as an instance that synchronizes the provision of a light flash, as emitted by the illumination assembly, with the shutter/exposure of the image sensor of the monochrome digital camera. The sequential provision of illumination and the taking of separate images may also be referred to as the provision of a series/sequence of instances of illumination and an associated series/sequence of instances of acquisition of monochrome digital images.

The control unit is configured to control the illumination assembly to sequentially provide illumination with the three wavelength ranges and is configured to control the monochrome digital camera to take separate images during illumination of the stage with the three wavelength ranges. By providing illumination with three different wavelength ranges and by taking separate images for the instances of illumination with the different wavelength ranges, it is possible to acquire image data that allows for assembling a color image. Accordingly, a color representation may be achieved, without relying on a color camera. The monochrome image data and the assembled color image may be representations of a portion of the sample, with the size of the portion of the sample depending on the magnification implemented in the optical system. It is also possible that the monochrome image data and the color image provide a full representation of the sample, e.g. in the form of an overview picture.

The digital microscope comprises a stage for holding a sample. The stage may be stationary within the digital microscope. However, it is also possible that the stage is movable with respect to the monochrome digital camera, the optical system, and the illumination assembly. In particular, the stage may be movable in an x-y-plane, with the light, passing from the illumination assembly through the stage, to the optical system, and to the monochrome digital camera, being substantially in a z-direction. Different portions of a sample may be illuminated and captured by the digital camera via moving of the stage. The stage may have a light transmissive portion, onto which the sample may be placed. It is also possible that the stage has a frame-like structure, with the sample being placed in an empty space in the center of said frame. In this way, the stage does not interfere at all with the light path from the illumination assembly to the monochrome digital camera. The sample may also be referred to as specimen herein. The sample may be provided in the form of a microscope slide. The substance/material to be examined may be placed on/within said slide, and the slide may provide a well-defined mechanical structure for placing the sample reliably on the stage.

The monochrome digital camera, the optical system, and the illumination assembly may be substantially stationary in the digital microscope. In particular, the illumination assembly may be entirely stationary in the digital microscope. The optical system and the monochrome digital camera may be slightly movable in terms of their distance to the stage, e.g. for setting a focal plane in accordance with a particular sample being examined. It is also possible that the optical system and the monochrome digital camera may be adaptable in position on a larger scale, e.g. for adapting the digital microscope to different levels of magnification in the optical system.

The digital microscope has an optical system, arranged between the stage and the monochrome digital camera. The optical system may comprise a microscope objective and a tube objective. The magnification of the sample may be set by the particular designs of the microscope objective and the tube objective. The microscope objective and/or the tube objective may be exchangeable, so that different magnifications may be implemented. The tube objective may be arranged between the microscope objective and the monochrome digital camera. The tube objective may also be referred to as tube lens.

According to a further embodiment, the control unit is configured to control the illumination assembly to sequentially provide light flashes with the three wavelength ranges. By providing the illumination with the three different wavelength ranges as light flashes, the illumination duration may be suitably set on the basis of the overall system considerations. For example, a sensitivity of the monochrome digital camera and/or an optical efficiency of the optical system and/or an optical efficiency of the interior set-up of the illumination assembly and/or an intensity of the light source(s) within the illumination assembly and/or other factors may be taken into account. The control unit may in particular be configured to control the illumination assembly to provide light flashes of a duration of less than 10 ms, further in particular less than 1 ms, further in particular less than 100 μs. With the given light flash durations, a high acquisition speed for the sequence of separate images may be achieved, while giving the monochrome digital camera a convenient window for opening the shutter/exposing the image sensor. Further in particular, the control unit may be configured to control the illumination assembly to provide light flashes of a duration of between 5 μs and 100 μs. In this way, the light flashes may provide illumination over the full shutter time, even when a very fast monochrome digital camera with a shutter time of 5 μs is used, while allowing for a very quick sequence of light flashes with different wavelength ranges and, thus, for a very quick acquisition of image data.

According to a further embodiment, the control unit is configured to control the stage to move, while the monochrome digital camera takes the separate images during illumination of the stage with the three wavelength ranges. In particular, the control unit may be configured to control the stage to move continuously, while the monochrome digital camera takes the separate images during the illumination of the stage with the three wavelength ranges. By moving the stage during the acquisition of the image data and the sequential illumination with the three wavelength ranges, the acquisition of the three monochrome digital images may be conveniently embedded into a high-speed scanning of the sample with the digital microscope. Further in particular, with the control unit controlling the illumination assembly to repeatedly cycle through the sequence of illumination with the three wavelength ranges, different portions of the sample may be photographed with three different wavelength ranges. This in turn may allow for the individual images to be stitched, in order to generate a large area representation of the sample. Both the space dimension with respect to the sample and the wavelength dimension with respect to the illumination may be taken care of by a single motion of the stage and an according synchronized control of the stage, the monochrome digital camera and the illumination assembly.

According to a further embodiment, the control unit is configured to control the illumination assembly to cycle through the three wavelength ranges for sequentially providing illumination with the three wavelength ranges in a repetitive pattern. The control unit may further be configured to control the monochrome digital camera to take a sequence of monochrome digital images, with each of the separate digital monochrome images being associated with a particular position of the stage and a particular one of the three wavelength ranges. The control unit or a downstream image processing device may be configured to combine the sequence of monochrome digital images. In particular, the control unit or the downstream image processing device may be configured to stitch image data from different positions of the stage and to generate color representations from monochrome image data stemming from illumination with different wavelength ranges.

According to a further embodiment, the control unit is configured to control the stage to move an offset distance between the separate images, with the offset distance substantially corresponding to a pixel distance or to a multiple of the pixel distance in the monochrome digital camera. An offset distance which substantially corresponds to a pixel distance or to a multiple of the pixel distance in the monochrome digital camera may also be referred to as a distance that has an offset accuracy of between 90% and 110%, in particular of between 95% and 105% of one pixel. In this way, despite the motion of the stage, separate images, as taken in sequence by the monochrome digital camera, may be aligned in a particularly convenient manner. In particular, the alignment between the separate images may be carried out without post-processing in the form of feature detection in the separate images or the like.

According to a further embodiment, the three wavelength ranges comprise a first wavelength range containing blue light, a second wavelength range containing green light, and a third wavelength range containing red light. In this context, blue light may be defined as light having a wavelength of between 450 nm and 490 nm. Further, green light may be defined as light having a wavelength of between 490 nm and 560 nm. Further, red light may be defined as light having a wavelength of between 630 nm and 700 nm. With the first wavelength range containing blue light, the second wavelength range containing green light, and the third wavelength range containing red light, a broad coverage of the visible spectrum may be achieved via the three wavelength ranges. Further, with the three wavelength ranges containing blue light, green light and red light, the separate monochrome digital images may provide for a good basis for generating a color image during the image processing.

According to a further embodiment, the first wavelength range overlaps the second wavelength range and/or the second wavelength range overlaps the third wavelength range. In particular, the first wavelength range may overlap the second wavelength range and the second wavelength range may overlap the third wavelength range. Taking separate monochrome digital images with wavelength ranges that overlap may allow for the generation of color images that are perceived as particularly natural representations by a human observer. In particular, the using of overlapping wavelength ranges may lead to color images that are perceived as being highly accurate in terms of their color representation. This result may at least in part be due to the overlap of the wavelength ranges being similar to how the human uvulae work. While being targeted to different colors, human uvulae have some sensitivity to neighboring colors, such that the human brain can infer detailed color information from said transition region between neighboring colors.

According to a further embodiment, the first wavelength range extends at least from 390 nm to 520 nm and/or the second wavelength range extends at least from 470 nm to 640 nm and/or the third wavelength range extends at least from 570 nm to 780 nm.

According to a further embodiment, the three wavelength ranges jointly cover the visible light spectrum. In particular, the three wavelength ranges may jointly extend at least from 390 nm to 780 nm. It is possible that the joint coverage by the three wavelength ranges extends into the infrared light range and/or the ultraviolet light range. Covering the full visible light spectrum may also contribute to a particularly natural and accurate color representation, when assembling the separate monochrome digital images.

According to a further embodiment, the illumination assembly comprises: a first light generation unit for generating a first light output with a first wavelength range; a second light generation unit for generating a second light output with a second wavelength range; a third light generation unit for generating a third light output with a third wavelength range; and a light output combination assembly configured to direct the first light output, the second light output, and the third light output to a sample illumination light path. Each of the first, second, and third light generation units may comprise one or more light sources and one or more optical elements. For example, a light generation unit may comprise a light source, such as an LED, a collimating lens for collimating the light output of the light source, and potentially one or more further optical elements, such as a color filter. In particular, the first light generation unit may comprise a first light source, in particular a first LED, and one or more first light conditioning element(s). Further in particular, the second light generation unit may comprise a second light source, such as a second LED, and one or more second light conditioning element(s). Further in particular, the third light generation unit may comprise a third light source, such as a third LED, and one or more third light conditioning element(s). The sample illumination light path is a common light path for the three light outputs. It may also be referred to as a common sample illumination light path. By providing three separate light generation units, the light outputs with the three different wavelength ranges may be generated separately and may be individually adapted and optimized for the complementary properties that may be desired in the separate monochrome digital images.

According to a further embodiment, the light combination assembly comprises a first light joining element and a second light joining element, with the first light output and the third light output being directed to an intermediate light path by the first light joining element and with the intermediate light path and the second light output being directed to the sample illumination light path by the second light joining element. In this way, a two-stage joining of the first, second, and third light outputs may be realized. The two-stage joining may allow for the first light joining element and the second light joining element to be adapted to exactly two light components to be joined and may provide for said targeted joining to take place in a particularly optically efficient manner. The light combination assembly may be arranged in a parallel light path portion of the illumination assembly. In particular, the first light joining element and the second light joining element may be arranged in a portion of the illumination assembly where the first light output, the second light output, and the third light output are comprised of at least substantially parallel light rays.

According to a further embodiment, each of the first light joining element and the second light joining element is one of a dichroic mirror and a semi-permeable mirror. In a particular embodiment, the first light joining element is a dichroic mirror and the second light joining element is a semi-permeable mirror. The semi-permeable mirror may for example be a 50/50 mirror, reflecting 50% of the incident light and passing 50% of the incident light. The combination of the dichroic mirror as the first light joining element and the semi-permeable mirror as the second light joining element may provide for a particularly good optical efficiency, in particular when using overlapping wavelength ranges. Even when the second wavelength range overlaps with both the first and the third wavelength ranges, the dichroic mirror may combine the first wavelength range and the third wavelength range in a highly accurate and highly efficient manner. The semi-permeable mirror may then accurately join the combination of the first wavelength range and the third wavelength range with the second wavelength range, while providing only a single instance of a substantial optical efficiency loss. In this context, it is noted that the first, second, and third light outputs are not provided at the same time. However, the considerations regarding optical efficiency, when joining the light paths of the first, second, and third light outputs, is still relevant, because the separate monochrome digital images, resulting from the sequence of instances of illumination with the three different wavelengths, are put together in the downstream image processing, when generating the color image.

According to a further embodiment, each of the first light generation unit, the second light generation unit, and the third light generation unit has one of the following features: (i) the respective light generation unit comprises a light source, emitting light of the respective wavelength range; (ii) the respective light generation unit comprises a light source and a color filter, the color filter transmitting light of the respective wavelength range; (iii) the respective light generation unit comprises a light source and a wavelength converter, the wavelength converter converting light from the light source into light of the respective wavelength range; (iv) the respective light generation unit comprises a light source, a wavelength converter and a color filter, the wavelength converter converting light from the light source into an intermediate wavelength range and the color filter transmitting light of the respective wavelength range. In a particular embodiment, the first light generation unit comprises a white light source, in particular a white LED, and a blue color filter and/or the second light generation unit comprises a blue light source, in particular a blue LED, and a color converter, outputting a lime-color spectrum, and/or the third light generation unit comprises a white light source, in particular a white LED, and a red color filter.

According to a particular embodiment, the first light generation unit comprises a first ultraviolet light source, in particular a first ultraviolet LED, and a first color converter and/or the second light generation unit comprises a second ultraviolet light source, in particular a second ultraviolet LED, and a second color converter and/or the third light generation unit comprises a third ultraviolet light source, in particular a third ultraviolet LED, and a third color converter. With the combination of an ultraviolet light source and a color converter, an efficient provision of a desired wavelength range may be provided, without having to rely on a color filter. The ultraviolet light source may emit such short wavelengths that all visible light wavelengths can potentially be provided via conversion. The use of color converters may allow for an efficient and low-cost provision of extended wavelength ranges, as compared to solutions where color filters are custom-designed for passing a particular spectrum with a gradual intensity distribution.

According to a further embodiment, the digital microscope further comprises a second illumination assembly arranged for coupling at least one fluorescence excitation spectrum into the optical system for providing a fluorescence excitation to the sample. As compared to the illumination assembly described hereinbefore, the second illumination assembly is arranged on the opposite side of the stage. In other words, the monochrome digital camera and the second illumination assembly are positioned on the same side of the stage. The second illumination assembly is configured to provide the at least one fluorescence excitation to the sample via the optical system, with the sample's response to the fluorescence excitation again passing the optical system and being captured by the monochrome digital camera. By providing fluorescence excitation, the monochrome digital camera may be used for yet another mode of image acquisition. As compared to previous approaches for light microscopes that have an added function of a fluorescence microscope and that rely on switching between a color camera for the light microscope function and a monochrome camera for the fluorescence microscope function, exemplary embodiments of the invention may allow for eliminating the need for different kinds of cameras. This in turn may eliminate the need for moving cameras within the microscope, which may pose an undesired limitation in terms of alignment accuracy, and/or the need for splitting the light path before reaching the cameras, which may pose an undesired limitation in terms of image acquisition sensitivity. The functionality of a fluorescence microscope may be embedded into the digital microscope at a comparably low increase in complexity.

The second illumination assembly may be arranged for coupling at least one fluorescence excitation spectrum into the optical system. The second illumination assembly may be stationary within the digital microscope and may comprise a coupling element, arranged within the optical system. At said coupling element, the fluorescence excitation may be coupled into the light path of the optical system. The coupling element may be arranged between the microscope objective and the tube objective. It is also possible that the second illumination assembly is movable between a disengaged position and an operation position/engaged position. In the disengaged position, the second illumination assembly may be completely removed from the light path of the optical system. In the operation position/engaged position, the second illumination assembly may be moved to a position with respect to the optical system where a coupling element of the second illumination assembly is arranged for coupling the fluorescence excitation spectrum into the optical path of the optical system. The coupling element may be arranged between the microscope objective and the tube objective in the operation position/engaged position. The moving of the second illumination assembly may be carried out via a dedicated electric motor or the like. The coupling element may be a dichroic mirror or another suitable optical structure for coupling the at least one fluorescence excitation spectrum into the light path through the optical system. In case the coupling element is a dichroic mirror, the dichroic mirror may in particular be configured to reflect the fluorescence excitation spectrum and to pass the spectrum expected from the sample in response to the fluorescence excitation. The spectrum expected in response may be a particular spectrum expected due to the provision of the sample with a particular fluorescent die/marker.

According to a further embodiment, the second illumination assembly comprises: a first fluorescence excitation unit for generating a first fluorescence excitation output having a first excitation spectrum; a second fluorescence excitation unit for generating a second fluorescence excitation output having a second excitation spectrum; an excitation joining element, with the first fluorescence excitation output and the second fluorescence excitation output being directed to a joined excitation path by the excitation joining element; and a multiple bandpass dichroic mirror, configured to reflect both the first excitation spectrum and the second excitation spectrum. In this way, the digital microscope may allow for excitation with two different fluorescence excitation spectrums and may allow for the monochrome digital camera to capture the response to the different fluorescence excitation spectrums via separate images. Using different fluorescence excitation spectrums may in particular be beneficial, where a sample has been treated with different dies/markers that have different fluorescent properties. For example, the sample may have been treated with two different fluorescent substances, with the two different fluorescent substances reacting to different excitation frequencies or reacting with different intensities to different excitation frequencies. The excitation joining element may for example be a dichroic mirror or a semi-permeable mirror.

Fluorescent substances can be configured to adhere to different structures in a sample. In this case, different kinds of images may be generated with the monochrome digital camera. For example, in the case of the sample being a tissue sample, different fluorescent markers may be applied, with one of them adhering to cell walls and another one adhering to cell nuclei.

According to a further embodiment, the multiple bandpass dichroic mirror is transmissive for a first response spectrum and a second response spectrum, as emitted from the sample after excitation with the first excitation spectrum and the second excitation spectrum. In other words, the multiple bandpass dichroic mirror may be configured to be reflective for the excitation spectrums and may be configured to be transmissive for the response spectrums. The multiple bandpass dichroic mirror may be adapted to particular excitation units on the one hand and particular dies/markers on the other hand.

According to a further embodiment, the second illumination assembly comprises more than two fluorescence excitation units, such as three, four, five or more fluorescence excitation units. The second illumination assembly may further comprise two or more excitation joining elements, with said two or more excitation joining elements directing the fluorescence excitation outputs of the three or more fluorescence excitations units to a joint excitation path. The multiple bandpass dichroic mirror may be configured to reflect said three or more excitation spectrums and may be configured to be transmissive for three or more response spectrums, as emitted from the sample after excitation with said three or more excitation spectrums.

According to a further embodiment, the multiple bandpass dichroic mirror is arranged within the optical system, in particular arranged between the microscope objective and the tube objective. In an alternative embodiment, the multiple bandpass dichroic mirror is movable to an operation position within the optical system, in particular movable to an operation position between the microscope objective and the tube objective. The multiple bandpass dichroic mirror may further be movable to a disengaged position, not affecting the light path between the optical system and the monochrome digital camera. The multiple bandpass dichroic mirror may be movable individually or may be movable, as an integral part of the second illumination assembly, by moving the second illumination assembly.

According to a further embodiment, the second illumination assembly comprises a filter wheel. The filter wheel may have a plurality of filter elements that can be rotated into and out of the optical path through the optical system. In particular, the filter wheel may be arranged between the dichroic mirror, forming the coupling element for the fluorescence excitation spectrum(s) into the optical system, and the monochrome digital camera, in particular arranged between the dichroic mirror and the tube objective of the optical system. The filter wheel may have an at least substantially transparent element, which may be present in the optical path, when the light microscope functionality is used. This at least substantially transparent filter element may be a transparent piece of material, such as a piece of glass or PMMA. It is also possible that an empty space in the filter wheel forms said at least substantially transparent filter element. In other words, a filter-less position may form part of the filter wheel. The filter wheel may further comprise one or more filter elements that are adapted to one or more response spectrums, as expected to be emitted from the sample after excitation with the one or more excitation spectrums.

Exemplary embodiments of the invention further include a digital microscope system, comprising: a digital microscope, as described in accordance with any of the embodiments above; and an image processing unit; wherein the image processing unit is configured to generate a color image from the separate images taken during illumination with the three wavelength ranges. The image processing unit may be implemented as a dedicated hardware component. It is also possible that the image processing unit is embodied as a software component. This software component may be run on a standard personal computer or server. It is also possible that the image processing unit is embodied as a combination of a dedicated hardware component, equipped with a software component for generating the color image. The image processing unit may further be configured to stitch multiple color images and/or to stitch monochrome images, as taken during multiple cycles through the illumination with the three wavelength ranges, before generating the color image. The additional features, modifications and effects, as described above with respect to the digital microscope, apply to the digital microscope system in an analogous manner.

According to a further embodiment, the digital microscope system further comprises a screen. The digital microscope system may be configured to depict a color image, generated from the separate images taken during illumination with the three wavelength ranges, on the screen. The digital microscope may further be configured to depict one or more images, generated from the one or more response spectrums, captured upon excitation with the one or more fluorescence excitation spectrums.

Exemplary embodiments of the invention further include a method of operating a digital microscope comprising: sequentially illuminating a sample on a stage of the digital microscope with three different wavelength ranges; and taking separate images with a monochrome digital camera of the digital microscope during the illuminating with the three different wavelength ranges. The additional features, modifications and effects, as described above with respect to the digital microscope, apply to the method of operating a digital microscope in an analogous manner.

According to a further embodiment, the method further comprises: generating a color image from the separate images taken during the illuminating with the three different wavelength ranges.

Exemplary embodiments of the invention further include a method of generating an assembled image with a digital microscope, the assembled image representing at least a portion of a sample arranged on a stage of the digital microscope, the method comprising: scanning the sample by repeatedly carrying out the method of operating the digital microscope in accordance with any of the embodiments described above. Said repeated carrying out of the method of operating the digital microscope comprises repeatedly carrying out said method for different positions of the stage. The method of generating an assembled image may comprise: moving the stage and carrying out the method of operating the digital microscope during said moving of the stage. The moving of the stage may be carried out as an at least partially continuous motion of the stage, with the taking of separate images with the monochrome digital camera being carried out during said continuous motion. It is also possible that said moving of the stage is carried out as a start-stop-motion, with the taking of three separate images during the illumination with three different wavelength ranges taking place when the stage is in a stopped position. The method of generating the assembled image may further comprise: stitching of individual color images, with each of the individual color images being generated from separate images taken during the illumination with three different wavelength ranges. The additional features, modifications and effects, as described above with respect to the digital microscope and with respect to the method of operating a digital microscope, apply to the method of generating an assembled image in an analogous manner.

DETAILED DESCRIPTION OF THE INVENTION

FIG.1shows a digital microscope2in accordance with an exemplary embodiment of the invention in a perspective, three-dimensional view. The digital microscope2has a base4, which supports the digital microscope2. The base4may be placed on a table for providing a secure stand.

The base4comprises an illumination assembly and a stage drive assembly, which are housed within and blocked from view inFIG.1by a base housing. A stage10is mounted to the base4. The stage is movable with respect to the base4. In particular, the stage10is movable in two dimensions, referred to as x- and y-directions herein. In operation, the stage10is moved by the stage drive assembly in the x- and y-directions.

The stage10has a light transmissive portion. A sample may be placed on the light transmissive portion of the stage10. In the operating scenario depicted inFIG.1, two slides12are arranged on the stage via a clipping mechanism. Each of the two slides12comprises a sample14, also referred to as specimen herein. The slides12are placed on the stage10in such a way that the samples14are placed at the light transmissive portion of the stage10. The light transmissive portion may be made from a transparent or translucent material or may be a cut-out portion of the stage10. In the latter case, the stage10forms a frame, through which light is emitted from the illumination assembly. The plane of that portion of the stage10where the samples are arranged is referred to as the x-y-plane of the digital microscope.

The digital microscope2further comprises a support arm6and an optics and camera housing8. The support arm6is shaped to support the optics and camera housing8, such that the optics and camera housing8hovers over the stage10. The optics and camera housing8houses various optical components. In particular, the optics and camera housing8houses a monochrome digital camera and an optical system, which in turn has a tube objective and a microscope objective28in the exemplary embodiment ofFIG.1. While the monochrome digital camera and the tube objective are blocked from view inFIG.1by the optics and camera housing8, the microscope objective28extends somewhat therefrom towards the stage10.

The optics and camera housing8is movable with respect to the support arm6in a moving direction orthogonal to the x-y-plane. In other words, the optics and camera housing8is movable in the z-direction of the digital microscope frame of reference. While this motion may be quite limited, it may be sufficient to bring a sample14in focus with respect to the optical system contained in the optics and camera housing8.

In operation, the stage drive assembly brings the stage10to desired positions in the x- and y-directions. The stage drive assembly may have any kind of suitable actuators, such as two small-scale electric motors for the two directions of movement. The illumination assembly provides for illumination of the sample12from underneath, and image data of a portion of the sample12, placed in the way of light from the illumination assembly to the monochrome digital camera, can be captured by the monochrome digital camera. Via driving the stage10to various positions, image data representing various portions of the sample14may be generated.

FIG.2shows selected components of a digital microscope2in accordance with an exemplary embodiment of the invention. The components of the digital microscope2are partially shown schematically and partially shown as function blocks. The depicted components may be embedded in the digital microscope2ofFIG.1or may be embedded into a different implementation of a digital microscope.

The digital microscope2comprises a monochrome digital camera20. The monochrome digital camera20has an image sensor22, which captures image data via a two-dimensional array of pixel sensors. For each pixel, the monochrome digital camera captures a single sensor value. The monochrome digital camera20may be viewed as a grey-scale camera, having a single sensor value dimension from black to white.

The digital microscope2further comprises an optical system24. The optical system24comprises a tube objective26and a microscope objective28. The microscope objective28and the tube objective26provide for magnification of the sample to be viewed via the digital microscope2and for directing the light, coming from the sample, towards the image sensor22of the monochrome digital camera20. Such optical systems, comprising a tube objective and a microscope objective, are known in the field of microscopes.

In operation, the optical system24and the monochrome digital camera20are arranged over the sample14, in order to capture image data, representing portions or all of the sample14. As described with respect toFIG.1, the sample14is held in position by a stage10of the digital microscope2. For ease of illustration, said stage is not depicted inFIG.2. Only the sample14is depicted as being exposed to the optical system24and the monochrome digital camera20.

The digital microscope2further comprises an illumination assembly30. The illumination assembly30is provided and configured for illuminating the sample14. In particular, the illumination assembly is provided for shining light onto the sample14, which light illuminates and passes the sample14. Said light causes a representation of all or of portions of the sample14to be captured in the monochrome digital camera20, after traveling through the microscope objective28and the tube objective26.

The illumination assembly30comprises a first light generation unit31, a second light generation unit41, and a third light generation unit51. The first light generation unit31is configured for generating a first light output with a first wavelength range. The second light generation unit41is configured for generating a second light output with a second wavelength range. The third light generation unit51is configured for generating a third light output with a third wavelength range.

The first light generation unit31comprises a first light source32, a first collimating lens34, and a first color filter36. In the exemplary embodiment ofFIG.2, the first light generation unit31is configured for generating a first light output with a first wavelength range containing blue light. In particular, in the exemplary embodiment ofFIG.2, the first wavelength range is between 390 nm and 520 nm. For generating the first light output, having said first wavelength range, the first light source32is a white LED, and the first color filter36is a bandpass filter, passing light within said first wavelength range therethrough. The first color filter36may in particular be a gradient filter, having a gradual edge design on one or both sides.

The second light generation unit41comprises a second light source42, a second collimating lens44, and a second color filter46. In the exemplary embodiment ofFIG.2, the second light generation unit41is configured for generating a second light output with a second wavelength range containing green light. In particular, in the exemplary embodiment ofFIG.2, the second wavelength range is between 470 nm and 640 nm. For generating the second light output, having said second wavelength range, the second light source42is a white LED, and the second color filter46is a bandpass filter, passing light within said second wavelength range therethrough. The second color filter46may in particular be a gradient filter, having a gradual edge design on one or both sides.

The third light generation unit51comprises a third light source52, a third collimating lens54, and a third color filter56. In the exemplary embodiment ofFIG.2, the third light generation unit51is configured for generating a third light output with a third wavelength range containing red light. In particular, in the exemplary embodiment ofFIG.2, the third wavelength range is between 570 nm and 780 nm. For generating the third light output, having said third wavelength range, the third light source52is a white LED, and the third color filter56is a bandpass filter, passes light within the third wavelength range therethrough. The third color filter56may in particular be a gradient filter, having a gradual edge design on one or both sides.

While it has been described that the first light source32, the second light source42, and the third light source52are white LEDs and the wavelength range conditioning takes place in the first color filter36, the second color filter46, and the third color filter56, respectively, the three different wavelength ranges may also be generated in different manners. For example, one or more light sources may be configured to provide a dedicated wavelength range. It is also possible that one or more light sources may be provided with a respective wavelength converter. In this way, the need for color filters may be eliminated or the wavelength range conditioning may be split up between the light source and/or the wavelength converter and/or the color filter. For example, the second light generation unit41may have a second light source42that emits blue light and may have a wavelength converter that generates a lime-colored spectrum. The lime-colored spectrum may be used as the second light output, potentially after some additional filtering via the second color filter.

The illumination assembly30further comprises a first light joining element60and a second light joining element64. The first light joining element60is configured to direct the first light output and the third light output to an intermediate light path62. The second light joining element64is configured to direct the light from the intermediate light path62and the second light output to a sample illumination light path66, also referred to as output light path66.

In the exemplary embodiment ofFIG.2, the first light joining element60and the second light joining element64are provided in a portion of the illumination assembly30, where the first light output, the second light output, and the third light output are collimated beams, being comprised of substantially parallel light rays. It may also be said that the first light joining element60and the second light joining element64are arranged in a parallel light path region of the illumination assembly30.

In the exemplary embodiment ofFIG.2, the first light joining element60is a dichroic mirror that passes light of the first wavelength range, i.e. light within the wavelength range of between 390 nm and 520 nm, therethrough and that reflects light of the third wavelength range, i.e. light within the wavelength range of between 570 nm and 780 nm. With the first wavelength range and the third wavelength range being disjunct, i.e. with the first wavelength range and the third wavelength range not overlapping, the dichroic mirror60may be configured to join all or substantially all of the first light output and the third light output in a highly accurate and highly optically efficient manner.

In the exemplary embodiment ofFIG.2, the second light joining element64is a semi-permeable mirror, passing substantially half of the light from the intermediate light path62to the sample illumination light path66and reflecting substantially half of the second light output onto the sample illumination light path66. In this way, a loss of about 50% may be uniformly applied to the first light output, the second light output, and the third light output. Accordingly, about 50% of the first light output, the second light output and the third light output may be coupled out of the illumination assembly30on the common sample illumination light path66.

With the illumination assembly30ofFIG.2, a high optical efficiency may be achieved, without having to rely on any movable components. With the first light generation unit31, the second light generation unit41, the third light generation unit51, the first light joining element60, and the second light joining element64being stationary within the illumination assembly30, a highly accurate and highly reliable light output for all three wavelength ranges may be achieved. With the combination of the dichroic mirror and the semi-permeable mirror as the first and second light joining elements60,64, the joining of the three light outputs may be associated with a total loss of only about 50%.

In the exemplary embodiment ofFIG.2, the light on the sample illumination light path66is directed towards the sample14by a re-directing reflector68and a condenser70. The condenser70provides for a high light intensity at the sample14and a strong illumination of the sample14. Also, the collimating action of the condenser is adapted to the arrangement of the optical system24, contributing to a high representation quality in the digital images at short shutter speeds of the monochrome digital camera20. While the re-directing reflector68and the condenser70are depicted as being arranged outside the illumination assembly30, it is also possible to consider these optical elements as part of the illumination assembly30. Further, it is possible to arrange the components of the illumination assembly30in different orientations, eliminating the need for the re-directing reflector68.

The digital microscope2further comprises a control unit72. The control unit72is coupled to the monochrome digital camera20and to the illumination assembly30. The control unit72is in particular configured for controlling the monochrome digital camera20and the illumination assembly30. The control unit72comprises a timing unit74, which is configured for providing a synchronized control of the monochrome digital camera20and the illumination assembly30. The timing unit74is coupled to the first light source32via a first illumination control line80. The timing unit74is coupled to the second light source42via a second illumination control line82. The timing unit74is coupled to the third light source52via a third illumination control line84. Via the first illumination control line80, the second illumination control line82, and the third illumination control line84, the timing unit74is able to selectively provide illumination via the first light generation unit31or the second light generation unit41or the third light generation unit51. The timing unit74is coupled to the monochrome digital camera via a camera control line76and via a camera feedback line78. In this way, the timing unit74can control the monochrome digital camera20to capture image data, and the monochrome digital camera20can provide feedback on the capturing of image data. The monochrome digital camera20is further coupled to the control unit72via an image data connection86. The control unit72is configured to receive image data via said image data connection86and to pass on said image data via an image data interface88for downstream image processing.

In operation, the timing unit74synchronizes the illumination assembly30and the monochrome digital camera20. In particular, the timing unit74provides a sequence of light flashes with the first wavelength range, the second wavelength range and the third wavelength range. For each of these light flashes, the timing unit74controls the monochrome digital camera20to capture image data of the sample14. In this way, the control unit72may cause a sequence of monochrome digital images to be taken by the monochrome digital camera20, with subsequent ones of the monochrome digital images representing the sample14under different illumination conditions. With the three monochrome digital images taken at said first, second, and third wavelength ranges, as described above, the image data, as taken by the monochrome digital camera20, may be assembled into a color image in the downstream image processing. Accordingly, sufficient image data is generated to provide color images of the sample14, without having to rely on a color camera in the digital microscope2.

The control unit72may further be coupled to the stage10of the digital microscope2, which is not shown inFIG.2, but for example illustrated inFIG.1. Via a coordinated control of the stage10, the monochrome digital camera20, and the illumination assembly30, the control unit72may cause a scanning of the sample14to be carried out. In particular, the stage10may be controlled to move in a row-wise or column-wise manner, in particular in a meandering manner, and a series of monochrome digital images may be taken during the motion of the stage10. The series of images may comprise subsets of images, each subset representing different portions of the sample at illumination with a particular wavelength range. The downstream image processing may on the one hand stitch the image data, as taken by the monochrome digital camera20, and may on the other hand assemble the monochrome images into color images.

FIG.3illustrates three exemplary wavelength ranges, as may be provided by the first light generation unit31, the second light generation unit41, and the third light generation unit51of the digital microscope2ofFIG.2. In particular,FIG.3illustrates a first light output spectrum38, which may be the spectrum of the first light output, as described above with respect toFIG.2. Further in particular,FIG.3illustrates a second light output spectrum48, which may be the spectrum of the second light output, as described above with respect toFIG.2. Yet further in particular,FIG.3illustrates a third light output spectrum58, which may be the spectrum of the third light output, as described above with respect toFIG.2.

As can be seen fromFIG.3and as is apparent from the description of the first, second and third wavelength ranges above, the first wavelength range overlaps with the second wavelength range and the second wavelength range overlaps with the third wavelength range. In other words, the first light output spectrum38overlaps with the second light output spectrum48and the second light output spectrum48overlaps with the third light output spectrum58.

The overlapping of the first and second wavelength ranges and of the second and third wavelength ranges allows for a particularly natural representation of the color image, after assembling the monochrome digital images, as taken by the monochrome digital camera20. The overlap allows for the monochrome digital images to have image information that allows for the human observer to gauge the color content in the transition regions between the different wavelength ranges particularly well. In this way, the resulting color images may be perceived as particularly accurate and/or particularly natural in terms of their colors.

FIG.4shows selected components of a digital microscope2in accordance with another exemplary embodiment of the invention. Similar toFIG.2, the digital microscope2ofFIG.4is partially depicted as a schematic diagram and partially depicted as a block diagram. Many of the components of the digital microscope2ofFIG.4are similar or identical to the respective components of the digital microscope2ofFIG.2. They are provided with the same reference numerals, and reference is made to their description above. In particular, the digital microscope2ofFIG.4has all the components of the digital microscope2ofFIG.2and is capable of performing the functionality described above. In addition, the digital microscope2ofFIG.4is capable of acting as a fluorescence microscope. For this purpose, the digital microscope2ofFIG.4has additional components, which will be described below.

The digital microscope2ofFIG.4comprises a second illumination assembly130. The second illumination assembly130comprises a first fluorescence excitation unit131and a second fluorescence excitation unit141. With the first fluorescence excitation unit, the second illumination assembly130is capable of generating a first fluorescence excitation output having a first excitation spectrum. With the second fluorescence excitation unit141, the second illumination assembly130is capable of generating a second fluorescence excitation output having a second excitation spectrum.

The first fluorescence excitation unit131comprises a first excitation source132, a first excitation collimating lens134, and a first excitation filter136. The second fluorescence excitation unit141comprises a second excitation source142, a second excitation collimating lens144, and a second excitation filter146. The second illumination assembly130further comprises an excitation joining element160. The excitation joining element160is arranged to direct the first fluorescence excitation output, as generated by the first fluorescence excitation unit131, and the second fluorescence excitation output, as generated by the second fluorescence excitation unit141, to a joined excitation path166. In the exemplary embodiment ofFIG.4, the excitation joining element160is a dichroic mirror, passing the first fluorescence excitation output, coming from the first fluorescence excitation unit131, and reflecting the second fluorescence excitation output, coming from the second fluorescence excitation unit141. In an alternative embodiment, the excitation joining element may be a semi-permeable mirror. In the exemplary embodiment ofFIG.4, the excitation joining element160is provided in a portion of the second illumination assembly130, where the first fluorescence excitation output and the second fluorescence excitation output are collimated beams, being comprised of substantially parallel light rays.

The second illumination assembly130further comprises an excitation condenser168and a multiple bandpass dichroic mirror170. The multiple bandpass dichroic mirror170is arranged to direct the first fluorescence excitation output and the second fluorescence excitation output from the joined excitation path166towards the microscope objective28and, thus, towards the sample14. The multiple bandpass dichroic mirror170reflects both the first excitation spectrum and the second excitation spectrum. In this way, the multiple bandpass dichroic mirror170is arranged and configured to provide two different kinds of fluorescence excitation to the sample14.

In operation, any of the first fluorescence excitation output and the second fluorescence excitation output may cause a fluorescent response at the sample14. In particular, the sample14may be provided with two fluorescent markers, with each of the two fluorescent markers reacting to one of the first excitation spectrum and the second excitation spectrum. The first and second markers may be configured to emit a fluorescent response that is somewhat longer in wavelength than the respective excitation spectrum. In other words, the fluorescent response may be lower energy radiation than the respective excitation. When being emitted from the sample14, the fluorescent responses travel through the microscope objective28, through the multiple bandpass dichroic mirror170of the second illumination assembly130, and through the tube objective26. Again, the microscope objective28and the tube objective26may be jointly referred to as the optical system24of the digital microscope2. The multiple bandpass dichroic mirror170is configured to be transmissive for both fluorescent responses. Accordingly, the fluorescent responses pass the multiple bandpass dichroic mirror170and travel towards the monochrome digital camera20.

In the exemplary embodiment ofFIG.4, the second illumination assembly130further comprises a filter wheel190. The filter wheel190is rotatable around a rotation axis192. The filter wheel190comprises a first filter194and a second filter196. The first filter194and the second filter196may be adapted to the fluorescent responses, as emitted by the sample14after being excited with the first fluorescence excitation output and the second fluorescence excitation output. In this way, radiation components that are not the result of the response of the sample14may be filtered out, and the resulting images, as taken by the monochrome digital camera20, may be a particularly accurate representation of the fluorescent responses.

In the exemplary embodiment ofFIG.4, the timing unit74is coupled to the first excitation source132via a first excitation control line180and coupled to the second excitation source142via a second excitation control line182. In this way, the control unit may provide for the selective provision of the first fluorescence excitation output or the second fluorescence excitation output. Together with the control of the monochrome digital camera20, the control unit72is configured to synchronize the fluorescence excitation by the second illumination assembly130and the capturing of image data of the fluorescent response by the monochrome digital camera20.

The second illumination assembly130may be stationary within the digital microscope2. In this case, the operation of the digital microscope2with the first wavelength range, the second wavelength range and the third wavelength range, as discussed above with respect toFIGS.2and3, takes place with the multiple bandpass dichroic mirror172arranged in the light path through the optical system24and to the monochrome digital camera20. In this case, the multiple bandpass dichroic mirror170is configured to be transmissive for all of the first wavelength range, the second wavelength range, and the third wavelength range. Accordingly, the multiple bandpass dichroic mirror170has no or only a small detrimental effect on the optical efficiency of the light microscope operation, described above with respect toFIGS.2and3. For this set-up, the filter wheel190may have a no-filter-portion, such that the light path between the multiple bandpass dichroic mirror170and the monochrome digital camera20is unaffected by the filter wheel190. Instead of a no-filter-portion, an at least substantially transparent filter element may be provided in the filter wheel190.

With the digital microscope2ofFIG.4, color images of a sample14as well as fluorescent response images of a sample14may be generated with the use of a single monochrome digital camera20. A wide range of functions may be achieved at a comparably low degree of complexity. Also, all of the discussed functions may be achieved with a set-up that has a stationary camera and does not rely on any sort of camera switching, neither via moving different cameras into the light path nor via splitting the light path before reaching different cameras.

While it has been described that the second illumination assembly130comprises a first fluorescence excitation unit131and a second fluorescence excitation unit141, it is also possible that the second illumination assembly130comprises only a single fluorescence excitation unit or more than two fluorescence excitation units, such as three or four or five or more fluorescence excitation units.

FIG.5illustrates exemplary fluorescence excitation spectrums and exemplary response spectrums, as may be present in the digital microscope2ofFIG.4, when operated as a fluorescence microscope. In particular, the first excitation spectrum138may be the spectrum of the first light output, as provided by the first fluorescence excitation unit131. The second excitation spectrum148may be the spectrum of the second light output, as provided by the second fluorescence excitation unit141. Both the first excitation spectrum138and the second excitation spectrum are comparably narrow spectrums. They may each be targeted to excite a particular fluorescent substance.

In the exemplary operating scenario ofFIG.4, the sample14may be furnished with a first marker and with a second marker. The first marker may be configured to react to the first excitation spectrum138, and the second marked may be configured to react to the second excitation spectrum148. In response to excitation with the first excitation spectrum138, the first marker may emit radiation with a first response spectrum139, as depicted inFIG.5. In response to excitation with the second excitation spectrum148, the second marker may emit radiation with a second response spectrum149, also depicted inFIG.5. The first and second response spectrums139,149have longer wavelengths than the respective excitation spectrums. Also, the intensity of the first and second response spectrums139,149is lower than the intensity of the first and second excitation spectrums138,148. These effects are due to the fluorescence action itself dissipating energy, which results in the longer wavelength, and due to the wider spread of the radiation of the response, as compared to the highly targeted first and second fluorescence excitation outputs.

The multiple bandpass dichroic filter170, as arranged in the second illumination assembly130of the digital microscope2ofFIG.4, is configured to reflect the wavelengths of the first and second excitation spectrums138,148and to pass the wavelengths of the first and second response spectrums139,149. In this way, the multiple bandpass dichroic mirror170is able to direct the first and second fluorescence excitation outputs from the second illumination assembly130towards the sample14and to pass the respective fluorescent responses, coming from the sample14, towards the monochrome digital camera20.

InFIG.5, the first excitation spectrum138is depicted as centered around a wavelength of about 375 nm, and the second excitation spectrum148is depicted as centered around a wavelength of about 475 nm. Further, the first response spectrum139is depicted as centered around a wavelength of about 420 nm, and the second response spectrum149is depicted as centered around a wavelength of about 540 nm. All of the first and second excitation spectrums138,148and the first and second response spectrums139,149are depicted as having a bandwidth of about 30 nm. It is pointed out that these values are exemplary only and that various considerations may be taken into account, when selecting the first and second excitation spectrums and the dies/markers, which determine the first and second response spectrums. For example, the embodiment of the second illumination assembly130being stationary or movable may be taken into account. With the second illumination assembly130being stationary, the multiple bandpass dichroic mirror170may be adapted to all of the first and second excitation spectrums138,148, the first and second response spectrums139,149, and the first, second, and third wavelength ranges discussed above with respect toFIGS.2and3.

As an example, some properties of common dies/markers will be laid out. For example, the DAPI marker may be excited with a fluorescence excitation spectrum extending between 352 nm and 402 nm, and the fluorescent response may be filtered for an associated fluorescent response spectrum from 417 nm to 477 nm. As a further example, the FITC marker may be excited with a fluorescence excitation spectrum extending between 450 nm and 500 nm, and the fluorescent response may be filtered for an associated fluorescent response spectrum from 515 nm to 565 nm. As a yet further example, the TRITC marker may be excited with a fluorescence excitation spectrum extending between 542 nm and 566 nm, and the fluorescent response may be filtered for an associated fluorescent response spectrum from 582 nm to 636 nm.

It is pointed out that the considerations regarding the moving of the stage of the digital microscope2, the scanning of the sample14via capturing image data at various positions of the stage, and the stitching of the image data for generating an assembled image, as laid out above with respect toFIG.2, apply to the fluorescence microscope functionality in an analogous manner.

FIG.6shows a digital microscope system200in accordance with an exemplary embodiment of the invention, partially depicted as a schematic diagram and partially depicted as a block diagram. The digital microscope system200comprises a digital microscope2. The digital microscope2may be a digital microscope2having the mechanical set-up as described with respect toFIG.1above and the optical and control set-up as described with respect toFIGS.2and3orFIGS.4and5above.

The digital microscope system200further comprises a computer202, coupled to the digital microscope2via an image data interface88. The digital microscope system200further comprises a screen204, coupled to the computer202. The computer202may be any kind of suitable processing device that has image processing capabilities and that provides for the interaction between the screen204and the digital microscope2in a suitable manner. The computer202may for example be a standard personal computer, embodied as a desktop computer or a laptop. The processing capacity, exemplarily provided by the computer202in the exemplary embodiment ofFIG.3, may also be embedded into the digital microscope2or into the screen204. The screen204may for example be part of a tablet or a smartphone, having both the screen functionality and the processing functionality for interfacing directly with the digital microscope2. It is also possible that the processing capacity, exemplarily provided by the computer202in the exemplary embodiment ofFIG.6, may be provided on a remote processing device, such as a remote server as part of a cloud-based solution.

FIG.6depicts an exemplary output on the screen204, after a sample has been scanned with the light microscope functionality, as described above with respect toFIGS.2and3, and after the sample has been scanned with the fluorescence microscope functionality, as described above with respect toFIGS.4and5. The output on the screen204comprises a color image210of the sample. The color image210may be generated and provided to the screen204by the computer202. The color image is the result of the assembling of a sequence of monochrome images, with the individual images of the sequence of monochrome images each corresponding to a particular position of the stage, i.e. to a particular portion of the sample, and resulting from illumination with a particular wavelength range. The output on the screen204further comprises a first fluorescent response image212, representing the response of the sample14to excitation with the first fluorescence excitation output. The output on the screen204further comprises a second fluorescent response image214, representing the response of the sample14to excitation with the second fluorescence excitation output. The first and second fluorescence response images212,214may be generated and provided to the screen204by the computer202. The first and second fluorescent response images212,214have image features at different portions of the sample14, indicating that different portions of the sample14have different properties. In particular, the different portions of the sample14may have sample elements, to which the first and second markers adhere differently.

The screen204may also be a control interface for the user of the digital microscope system200. In the exemplary embodiment ofFIG.6, the screen204is a touch screen, so that the screen204provides both user input functionality and image output functionality. The user may control the whole operation of the digital microscope system200via the touch screen204. However, it is also possible that other input devices are provided in addition/as an alternative to the touch screen204. For example, a keyboard and/or a mouse and/or any other suitable input device may be provided for the user to control the digital microscope system200. It is also possible that multiple screens are provided for the output of images. It is further possible that images are output to other entities. For example, images may be saved to a hard drive or other data storage medium in a file format.

The digital microscope and the digital microscope system, as described herein, may be used with any kind of sample/specimen. The sample may in particular be a biological sample. The biological sample may be a pathological sample, such as a human or animal tissue sample. The term tissue may refer to any kind of substance having been taken from a patient, with the term patient being understood to refer to humans and animals. Images of tissue samples taken from a dead human body or from a dead animal are also considered as being taken from a patient. The term tissue encompasses all kinds of substances of a human or animal body, such as skin tissue, bone tissue, muscle tissue, organ tissue, brain tissue, etc. The biological sample may also be a cell culture sample, for example taken from a yeast-containing substance.