Device for providing excitation light for the analysis of a biological sample by means of fluorescence measurement and method for operating such a device

Abstract

The invention relates to a device (100) for providing excitation light (L) for the analysis of a biological sample by means of fluorescence measurement. The device (100) comprises a light emission unit (110) configured to selectively emit first emission light (L1) via a first beam path (S1) or second emission light (L2) via a second beam path (S2). The device (100) also comprises a filter unit (120) configured to filter the first emission light (L1) and the second emission light (L2) to allow different excitation bands of the emission light (L1, L2) to pass through in order to generate the excitation light (L). The filter unit (120) comprises a plurality of interference filters (121, 122, 123, 124) for the excitation bands and a filter changing device (125) to which the interference filters (121, 122, 123, 124) are attached.The filter changing device (125) is configured to move the interference filters (121, 122, 123, 124) together and to position one of the interference filters (121, 122, 123, 124) in each beam path (S1, S2). The device (100) further comprises a deflection unit (130) configured to combine the beam paths (S1, S2) and direct them to an output (150) of the device (100) for the output of the excitation light (L). The deflection unit (130) is arranged in the beam paths (S1, S2) between the filter unit (120) and the output (150).

Description

State of the art

[0001] The invention relates to a device or a method according to the preamble of the independent claims. The present invention also relates to a computer program.

[0002] Particularly in the life sciences, numerous experimental methods, such as fluorescence microscopy, flow cytometry, quantitative PCR, histopathology, and the like, rely on fluorescence phenomena. A light source can be of particular importance in the relevant instruments, as fluorescence measurement requires excitation of the sample with precisely defined wavelength bands, usually with high spectral density. The light source must be able to switch between these excitation bands.

[0003] Traditionally, such light sources can be realized by, for example, 1) equipping a very broadband light source, e.g., a white LED, incandescent or gas discharge lamp, with interchangeable dielectric bandpass filters, which are arranged, for example, on a slider or wheel, or 2) using several light sources that a) have intrinsically limited spectral ranges (laser, SLD) and / or b) are more broadband (e.g., colored LED), but are each spectrally defined by a fixed bandpass filter.

[0004] Approach 1) requires, in particular, a light source whose spectrum is broad enough to cover all the required wavelength bands. This alone can be difficult, since, for example, commercially available white LEDs or remote phosphor sources only appear white to the eye, but in reality, due to their inherent design, have a significant gap in the spectrum between 450 and 500 nm and can also be very weak in the red range above 650 nm. A considerable amount of light can potentially be wasted here because, in each channel, only a band approximately 20 nm wide is extracted from a spectrum that is at least 20 times broader, e.g., 400–800 nm. The remaining light, for example, 90% or more, must be blocked by a high-quality bandpass filter, and the correspondingly sized source also generates heat. Approach 2a) uses comparatively expensive sources and also requires dichroic combiners.Approach 2b) can often be technically complex because each channel requires its own source with associated electronics. Furthermore, to combine the beam paths of the individual channels towards the sample, a dichroic filter is required for each channel after the first one. The installation position of this filter can be subject to very tight tolerances, which can necessitate increased adjustment effort. Disclosure of the invention

[0005] Against this background, the approach presented here comprises a device for providing excitation light for the analysis of a biological sample by means of fluorescence measurement, a method for operating such a device, a control unit that uses this method, and finally a corresponding computer program according to the main claims. Advantageous further developments and improvements of the device specified in the independent claim are possible through the measures listed in the dependent claims.

[0006] According to embodiments, a device can be used to provide excitation light for the analysis of a biological sample by means of fluorescence measurement. This device can direct light emitted from a light source unit through two beam paths, each with different, mechanically interchangeable interference filters, and a common mechanical actuator can be used to change the filters in both beam paths simultaneously. In light of the aforementioned prior art, this can also be understood as a hybrid approach for such a device.

[0007] A device for providing excitation light for the analysis of a biological sample by means of fluorescence measurement is presented, wherein the device has the following features: a light emission unit configured to selectively emit first emission light via a first beam path or second emission light via a second beam path, wherein the first beam path and the second beam path are at least partially separated from each other; a filter unit configured to filter the first emission light and the second emission light to allow different predefined excitation bands of the respective emission light to pass through in order to generate the excitation light, wherein the filter unit comprises a plurality of filters, interference filters for the different excitation bands, and a filter changing device to which the filters, in particular interference filters, are attached, wherein the filter changing device is configured to move the filters, interference filters, together and to arrange one of the filters, in particular interference filters, in each beam path; and a deflection unit configured to combine the beam paths and direct them to an output of the device for the output of the excitation light, wherein the deflection unit is arranged in the beam paths between the filter unit and the output.

[0008] In other words, the filter unit is designed to allow the first emission light and the second emission light to pass through in the wavelength range in which the phosphorescent material can be excited.

[0009] The filter changing device can be designed as a slider or a wheel. The filters or interference filters can be designed, in particular, as bandpass filters. The device can also include collimation optics for each beam path to align the respective beam of emitted light before it passes through the filter unit.

[0010] According to one embodiment, the filter changing device can be movable between a first position and a second position and can be configured to arrange a first filter or first interference filter in the first beam path and a third filter or third interference filter in the second beam path in the first position, and a second filter or second interference filter in the first beam path and a fourth filter or fourth interference filter in the second beam path in the second position. Thus, the filter changing device can have four interference filters. Such an embodiment offers the advantage that the excitation light can be provided with four channels in a simple, cost-effective, and reliable manner.

[0011] In this design, the first and second positions can be end positions of a movement path for the filter changing device. Such an embodiment offers the advantage that by moving the filter changing device only from one end position to the other, a structurally simple method for changing the filter can be implemented. In particular, this eliminates the need for a position encoder. Additionally or alternatively, the filter changing device can be driven electromagnetically or by means of a shape memory alloy. Such an embodiment offers the advantage that the filter change can be implemented simply and reliably using only a single drive unit.

[0012] The filter changing device can also be movable to at least one intermediate position between the first and second positions and can be configured to accommodate an additional filter or interference filter in the first beam path and an additional filter or interference filter in the second beam path in the intermediate position. Such an embodiment offers the advantage that more excitation light channels can be provided if required.

[0013] Furthermore, the light emission unit can be configured to emit the first emission light with a first spectrum and the second emission light with a second spectrum. The first and second spectra can differ at least partially from each other. Such an embodiment offers the advantage that optimized spectra can be generated for different excitation light channels, while still allowing the use of cost-effective components for the light emission unit.

[0014] According to one embodiment, the light emission unit can have a first light source for emitting the first emission light and a second light source for emitting the second emission light. These light sources can be configured as LEDs, superluminescent LEDs, or gas discharge lamps. Alternatively, the light sources can be configured as remote phosphor sources, each comprising a laser source and a phosphor. Such an embodiment offers the advantage that the first and second emission light can be generated reliably and in a structurally simple manner.

[0015] According to another embodiment, the light emission unit can comprise a remote phosphor source with a laser source, a first phosphor, and a second phosphor. The laser source can be switchable to selectively excite either the first phosphor to emit the first emission light or the second phosphor to emit the second emission light. Switching can be achieved by deflecting the laser beam, for example with a micromechanical mirror, by blocking and releasing a respective partial beam, for example with a mechanical shutter, or by a fiber optic arrangement. Such an embodiment offers the advantage that only one light source is required.

[0016] For example, the phosphors can include cerium-doped lutetium aluminum garnet, cerium-doped gadolinium garnet, gadolinium-substituted yttrium aluminum garnet, and / or cerium-doped yttrium aluminum garnet. The proportion of cerium doping can be varied. Additionally or alternatively, yttrium can be partially or completely substituted by other rare earth elements. Additionally or alternatively, aluminum can be substituted by other elements. In this way, the emission bands of the phosphor can be advantageously and precisely tailored to a specific application.

[0017] Furthermore, the deflection unit can comprise a first deflection device and a second deflection device. The first deflection device can include a mirror, while the second deflection device can include a dichroic mirror or an edge filter. In this way, an advantageous combination of the beam paths to the common output of the device can be achieved. Thus, the device can, for example, also be described as a hybrid excitation optic with filter switching and a dichroic mirror.

[0018] A method for operating an embodiment of a device presented herein is also presented, the method comprising the following steps: Controlling the light emission unit to selectively emit either the first emission light or the second emission light; and Activating the filter changing mechanism of the filter unit to generate the excitation light using one of the filters or interference filters.

[0019] The method can thus be implemented to operate a device for providing excitation light for the analysis of a biological sample by means of fluorescence measurement. Therefore, by implementing the method, excitation light can also be provided for the analysis of a biological sample by means of fluorescence measurement.

[0020] This process can be implemented, for example, in software or hardware, or in a hybrid form of software and hardware, for example in a control unit.

[0021] The approach presented here further creates a control unit that is configured to perform, control, or implement the steps of a variant of the method presented here in appropriate devices. This embodiment of the invention in the form of a control unit also allows the problem underlying the invention to be solved quickly and efficiently.

[0022] For this purpose, the control unit can have at least one processing unit for processing signals or data, at least one storage unit for storing signals or data, at least one interface to a sensor or actuator for reading sensor signals from the sensor or for outputting control signals to the actuator, and / or at least one communication interface for reading or outputting data embedded in a communication protocol. The processing unit can be, for example, a signal processor, a microcontroller, or the like, while the storage unit can be flash memory or a magnetic storage device.The communication interface can be configured to read or output data wirelessly and / or via wired connections, whereby a communication interface that can read or output wired data can, for example, read this data electrically or optically from or output it into a corresponding data transmission line.

[0023] In this context, a control unit can be understood as an electrical device that processes sensor signals and outputs control and / or data signals accordingly. The control unit can have an interface, which can be implemented in hardware and / or software. In the case of a hardware-based interface, the interfaces can, for example, be part of a so-called system ASIC, which incorporates various functions of the control unit. However, it is also possible that the interfaces are separate integrated circuits or at least partially comprised of discrete components. In the case of a software-based interface, the interfaces can be software modules that are, for example, present on a microcontroller alongside other software modules.

[0024] Furthermore, an analytical instrument for analyzing a biological sample is presented, wherein the analytical instrument comprises an embodiment of a device mentioned herein for providing excitation light for the analysis of a biological sample by means of fluorescence measurement. The analytical instrument is configured to analyze a biological sample by means of fluorescence measurement using the excitation light provided by the device. Optionally, the analytical instrument additionally comprises an embodiment of a control unit mentioned herein. The control unit can be connected to the light source unit and the filter changing device via signal transmission.

[0025] Also advantageous is a computer program product or computer program with program code that can be stored on a machine-readable carrier or storage medium such as a semiconductor memory, a hard disk memory or an optical memory and is used to carry out, implement and / or control the steps of the method according to one of the embodiments described above, in particular if the program product or program is executed on a computer or device.

[0026] Examples of the approach presented here are shown in the drawings and explained in more detail in the following description. It shows: Fig. 1 a schematic representation of an embodiment of a device for providing excitation light for the analysis of a biological sample by means of fluorescence measurement; Fig. 2 a schematic representation of switching states and spectra of the device Fig. 1; and Fig. 3 a flowchart of an embodiment of a method for operating a device for providing excitation light for the analysis of a biological sample by means of fluorescence measurement.

[0027] In the following description of favorable embodiments of the present invention, the same or similar reference numerals are used for the elements shown in the various figures and acting similarly, without repeating these elements.

[0028] Fig. Figure 1 shows a schematic representation of an embodiment of a device 100 for providing excitation light L for the analysis of a biological sample by means of fluorescence measurement. The device 100 is designed for use in an analytical instrument for analyzing the biological sample by means of fluorescence measurement. The device 100 can also be referred to as an excitation light supply device. The device 100 comprises a light emission unit 110, a filter unit 120, and a deflection unit 130.

[0029] The light emission unit 110 is configured to selectively emit either first emission light L1 via a first beam path S1 or second emission light L2 via a second beam path S2. The first beam path S1 and the second beam path S2 are at least partially separated from each other. According to one embodiment, the light emission unit 110 is configured to emit the first emission light L1 with a first spectrum and the second emission light L2 with a second spectrum, wherein the first spectrum and the second spectrum differ at least partially from each other; see also [reference to be added]. Fig. 2.

[0030] According to the embodiment shown here, the light emission unit 110 comprises a first light source 111 for emitting the first emission light L1 and a second light source 112 for emitting the second emission light L2. The light sources 111 and 112 are, for example, configured as light-emitting diodes, superluminescent diodes, or gas discharge lamps, or alternatively as remote phosphor sources, each with a laser source and a phosphor. According to another embodiment, the light emission unit 110 comprises a remote phosphor source with a laser source, a first phosphor, and a second phosphor. Here, the laser source is switchable to selectively excite either the first phosphor to emit the first emission light L1 or the second phosphor to emit the second emission light L2.

[0031] The filter unit 120 is configured to filter the first emission light L1 and the second emission light L2 to allow different predefined excitation bands of the emission light L1, L2 to pass through in order to generate the excitation light L. The filter unit 120 comprises a plurality of interference filters 121, 122, 123, 124 for the different excitation bands and a filter changing device 125 to which the interference filters 121, 122, 123, 124 are attached. The filter changing device 125 is configured to move the interference filters 121, 122, 123, 124 together. Furthermore, the filter changing device 125 is configured to position one of the interference filters 121, 122, 123, 124 in each beam path S1 and S2. The interference filters121, 122, 123, 124 are, for example, designed as bandpass filters.

[0032] According to the embodiment shown here, the filter changing device 125 of the filter unit 120 is movable between a first position and a second position. The filter changing device 125 is configured to arrange a first interference filter 121 in the first beam path S1 and a third interference filter 123 in the second beam path S2 in the first position. Furthermore, the filter changing device 125 is configured to arrange a second interference filter 122 in the first beam path S1 and a fourth interference filter 124 in the second beam path S2 in the second position. In the illustration of Fig. Figure 1 shows the first position. According to one embodiment, the first and second positions are end positions of a movement path of the filter changing device 125. Additionally or alternatively, the filter changing device 125 is driven electromagnetically or by means of a shape memory alloy. According to another embodiment, the filter changing device 125 is movable to at least one intermediate position between the first and second positions. In this intermediate position, the filter changing device 125 is designed to accommodate an additional interference filter for a further excitation band in the first beam path S1 and an additional interference filter for an additional excitation band in the second beam path S2.

[0033] The deflection unit 130 is designed to combine the beam paths S1 and S2 and direct them to an output 150 of the device 100 for the emission of the excitation light L. Thus, the deflection unit 130 is designed to combine the beam paths S1 and S2 into a common beam path S. The deflection unit 130 is arranged in the beam paths S1 and S2 between the filter unit 120 and the output 150. In other words, the filter unit 120 is arranged between the light emission unit 110 and the deflection unit 130.

[0034] According to the embodiment shown here, the deflection unit 130 comprises a first deflection device 131 and a second deflection device 132. The first deflection device 131 comprises a mirror and the second deflection device 132 comprises a dichroic mirror or an edge filter.

[0035] Furthermore, according to the embodiment shown here, the device 100 optionally also includes a first collimation optic 141 for parallelizing the first emission light L1 before it passes through the filter unit 120 and a second collimation optic 142 for parallelizing the second emission light L2 before it passes through the filter unit 120. The first collimation optic 141 and the second collimation optic 142 are arranged in the respective beam paths S1 and S2 between the light emission unit 110 and the filter unit 120.

[0036] The first beam path S1 runs from the first light source 111, through the optional first collimation optics 141 and through the filter unit 120. Here, due to the position of the filter unit 120 and its filter changing device 125, it passes through the first interference filter 121. It is deflected at the deflection unit 130, more precisely at the first deflection device 131, which is designed as a mirror. It then passes through the second deflection device 132, which is designed as a dichroic mirror or edge filter, and then runs along the common beam path S or forms part of it. The second beam path S2 runs from the second light source 112, through the optional second collimation optics 142 and through the filter unit 120. Here, due to the position of the filter unit 120, it passes through the second deflection device 132, which is designed as a dichroic mirror or edge filter.whose filter changing device 125 the third interference filter 123, and is deflected at the deflection unit 130, more precisely the second deflection device 132 designed as a dichroic mirror or edge filter, then runs along the common beam path S or forms part of it.

[0037] In other words, this is in Fig. The illustrated embodiment of the device 100 is suitable for the common case where four excitation bands are required. The four bands are, for example, at 470 nm, 530 nm, 580 nm, and 640 nm, and are each 20 nm wide or have a full width at half maximum (FWHM). The device 100 is based, in particular, on a hybrid approach in which two light sources 111 and 112 are each equipped with two different, mechanically interchangeable bandpass filters 121 and 122, and 123 and 124, respectively. Preferably, a common mechanical actuator, the filter changing device 125, is used to change the filters simultaneously in both beam paths S1 and S2. The mechanical filter change preferably has two positions, which is mechanically simpler to implement than three or more, since, for example, no stepper motor or position encoder is required. It is technically simpler to switch between two end positions.The use of two light sources, 111 and 112, represents an advantageous compromise between one source and four sources. A single source would need to be very broadband, at least 200 nm in the wavelength example mentioned above, and would therefore have a relatively low spectral density in the actually relevant spectral ranges. Specifically, this would mean that even a spectrally homogeneous source exactly 200 nm wide would only emit 10% of its intensity in a 20 nm wide band. 90% would have to be blocked by a very high-quality bandpass filter and would be lost as heat. Since the spectrum of real sources is rarely homogeneous and cannot be adjusted to freely selectable widths, the actual conditions could be even less favorable. Four sources, on the other hand, would require more components in the area of ​​passive optics, such as lenses, beam splitters, etc., and electronics, such as a regulated power supply, control circuitry, etc.

[0038] Light sources 111 and 112 are characterized by broad spectra, meaning their spectrum covers one or more of the desired channels. For example, two identical sources can be used, each covering all four channels. However, it is even more advantageous if the spectrum of one of the two light sources 111 and 112 is particularly intense in the regions of the two short-wavelength channels (e.g., 470 and 530 nm), and the spectrum of the other of the two light sources 111 and 112 is particularly intense in the regions of the two long-wavelength channels (e.g., 580 nm and 640 nm). Advantageously, the light sources 111 and 112 can be light-emitting diodes (LEDs), superluminescent diodes (SLDs), gas discharge lamps, or remote phosphor sources.

[0039] Remote phosphor sources are arrangements in which a laser excites a phosphor, thus creating an incoherent, broadband source with very high luminance. Their spectrum is determined by the phosphor used. Specifically, a cerium-doped lutetium aluminum garnet (LuAG:Ce), molecular formula Lu3Al5O, could be used for the two short-wavelength channels. 12 :Ce1% is used, for the two long-wavelength channels a cerium-doped gadolinium garnet (GdAG:Ce), molecular formula GdAG:Ce2% or gadolinium-substituted yttrium aluminum garnet, molecular formula (Gd,Y)3Al5O 12 Ce2%. In principle, cerium-doped yttrium aluminum garnet (YAG:Ce), molecular formula Y3Al5O, can also be used for each or both sources. 12YAG:Ce can be used, which is a commercially readily available standard phosphor. To compensate for wavelength ranges with potentially insufficient emissions, the fluorescence of the phosphor can be mixed with the exciting laser light. Those skilled in the art are aware of other options that are chemically similar to the aforementioned phosphor examples. In particular, starting with the well-known YAG:Ce, it is possible to change the emission band of the phosphor by varying the cerium doping, partially or completely substituting yttrium with other rare earth elements, or substituting aluminum with other elements. Alternatively, the two light sources 111 and 112 can also be implemented by using two phosphors that are excited by a common laser source. Switching between them is then achieved by deflecting the beam, e.g.,with a micromechanical mirror, by blocking / releasing a partial beam, e.g. with a mechanical shutter, or a fiber optic arrangement (switch).

[0040] The collimation optics 141 and 142, indicated in Fig. The beam is collimated by a lens (1) before passing through the respective bandpass filter 121 or 122, and 123 or 124. This is generally advantageous because bandpass filters only function well within a narrow angular range, but it is optional for device 100. There may be configurations in which collimation is unnecessary, for example, because the source already emits collimated light or because the divergence and its consequences can simply be accepted. Otherwise, collimation before the filter can be achieved using devices such as refractive lenses, Fresnel lenses, etc.

[0041] The filter changer or filter changing device 125 is a mechanical element with two positions, characterized in that in each position one of two filter pairs 121 and 123 or 122 and 124 is placed in the two beam paths S1 and S2. The filter changing device 125 can be, for example, a slide or a wheel, driven, for example, electromagnetically or by means of a shape memory alloy. It is advantageous if the two positions are mechanically end positions, i.e., a position encoder can be omitted.

[0042] The bandpass filters 121, 122, 123, 124 are advantageously dielectric interference filters. They are designed to transmit light in the region of the desired excitation band, preferably >90%, but to reflect light outside this band with a particularly high optical density, OD>4, on the immediate long-wavelength side of the band.

[0043] A dichroic mirror or edge filter, acting as a second deflection device 132, serves to combine the two beam paths S1 and S2. It is designed to reflect light above a certain wavelength and transmit light below it (short-pass filter). Alternatively, it can be configured in reverse to transmit long-wavelength light and reflect short-wavelength light (long-pass filter). Which variant is used depends on which of the light sources 111 and 112 is to provide the short-wavelength channels and which the long-wavelength channels. In the arrangement of Fig. A shortpass filter is to be used when the first light source 111 provides the short-wavelength channels. It then transmits the light from the short-wavelength channels, while the long-wavelength channels from the second light source 112 are reflected.

[0044] Fig. Figure 2 shows a schematic representation of switching states and spectra of the device 100. Fig. 1. This representation shows four switching states of the device 100 together with the associated spectra in a total of four columns.

[0045] The first column shows a first switching state of the device 100. In this first switching state, the first light source is used to generate the first emission light, and the filter unit is arranged in the first position, in which the first interference filter is positioned in the first beam path to filter the first emission light. Furthermore, a first spectrum 211 of the first light source is schematically plotted as intensity I against wavelengths λ, where characteristic wavelengths λ are also shown. 1,The graph shows λ2, λ3, and λ4 of four excitation bands, which, for illustrative purposes, could be located at 470 nm, 530 nm, 580 nm, and 640 nm. Additionally, a passband 221 of the first interference filter or bandpass filter is plotted as transmittance T over wavelengths λ, with the first wavelength λ1 being the first due to the passband 221. Finally, a first excitation band 251, resulting from filtering the first spectrum 211 with the passband 221, is also plotted as intensity I over wavelengths λ.

[0046] A second column shows a second switching state of the device 100. In this second switching state, the first light source is used to generate the first emission light, and the filter unit is arranged in the second position, in which the second interference filter is positioned in the first beam path to filter the first emission light. Furthermore, the first spectrum 211 of the first light source is again schematically plotted as intensity I against wavelengths λ, with the characteristic wavelengths λ1, λ2, λ3, λ4 of the four excitation bands also shown, which, for example, can be 470 nm, 530 nm, 580 nm, and 640 nm. Additionally, a passband 222 of the second interference filter or bandpass filter is plotted as transmittance T against wavelengths λ, with the transmittance through the passband 222 being at a second wavelength λ2.Finally, a second excitation band 252 is also plotted as a result of filtering the first spectrum 211 with the passband 222 as intensity I over wavelengths λ.

[0047] A third column shows a third switching state of the device 100. In this third switching state, the second light source is used to generate the second emission light, and the filter unit is arranged in the first position, in which the third interference filter is positioned in the second beam path to filter the second emission light. Furthermore, a second spectrum 212 of the second light source is schematically plotted as intensity I against wavelengths λ, with the characteristic wavelengths λ1, λ2, λ3, λ4 of the four excitation bands also shown, which, for illustrative purposes, can be 470 nm, 530 nm, 580 nm, and 640 nm. Additionally, a passband 223 of the third interference filter or bandpass filter is plotted as transmittance T against wavelengths λ, with the transmittance through the passband 223 being at a third wavelength λ3.Finally, a third excitation band 253 is also plotted as a result of filtering the second spectrum 212 with the passband 223 as intensity I over wavelengths λ.

[0048] A fourth column shows a fourth switching state of the device 100. In this fourth switching state, the second light source is used to generate the second emission light, and the filter unit is arranged in the second position, in which the fourth interference filter is positioned in the second beam path to filter the second emission light. Furthermore, the second spectrum 212 of the second light source is again schematically plotted as intensity I against wavelengths λ, with the characteristic wavelengths λ1, λ2, λ3, λ4 of the four excitation bands also shown, which, for example, can be 470 nm, 530 nm, 580 nm, and 640 nm. Additionally, a passband 224 of the fourth interference filter or bandpass filter is plotted as transmittance T against wavelengths λ, with the passband 224 being located at a fourth wavelength λ4.Finally, a fourth excitation band 254 is also plotted as a result of filtering the second spectrum 212 with the passband 224 as intensity I over wavelengths λ.

[0049] In other words, the two individually activatable light sources and two filter positions, or positions of the filter unit, allow the realization of four excitation channels 251, 252, 253, and 254. Put another way, the individual switching between the two light sources and two filter positions allows the realization of four excitation channels. The first line of the diagram shows the thematic configurations or switching states, the second line the spectra of the currently active light source, the third line the spectra of the bandpass filter in the currently active beam path, and the fourth line the spectrum emitted by the device 100, which is produced by filtering the currently active light source with the respective associated bandpass filter.

[0050] Fig.Figure 3 shows a flowchart of an embodiment of method 300 for operating a device for providing excitation light for the analysis of a biological sample by means of fluorescence measurement. The operating method 300 can be carried out to operate the device from any of the figures described herein. Thus, the operating method 300 can be carried out in conjunction with the device from any of the figures described herein.

[0051] The operating procedure 300 comprises a step 310 of controlling the light emission unit to selectively emit either the first emission light or the second emission light. Furthermore, the operating procedure 300 comprises a step 320 of actuating the filter changing device of the filter unit to generate the excitation light using one of the interference filters.

[0052] If an embodiment includes an “and / or” connection between a first feature and a second feature, this is to be read as meaning that the embodiment according to one embodiment has both the first feature and the second feature, and according to another embodiment either only the first feature or only the second feature.

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