Light source unit and method for imaging device
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- LEICA MICROSYSTEMS CMS GMBH
- Filing Date
- 2023-06-08
- Publication Date
- 2026-06-17
AI Technical Summary
Existing broadband laser sources for fluorescence microscopy are expensive and have reduced lifetime due to stress on microstructured glass fibers, particularly lacking sufficient light output in the short wavelength region of the visible spectrum, such as blue, making them inefficient and costly.
A light source unit that receives broadband laser light, separates and amplifies a portion of it, and shifts its frequency to generate laser light with a second wavelength outside the original spectrum, especially in the blue region, using an optical amplifier and frequency changing unit, without requiring additional laser sources.
This configuration extends the laser light spectrum to include the blue region, enhances versatility, reduces costs, and extends the lifetime of the broadband laser source by avoiding damage to microstructured fibers, enabling applications like pulse-interleaved excitation microscopy.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to a light source unit for an imaging device. The present invention further relates to a method for generating laser light.
Background Art
[0002] Typical laser light sources generate laser light that includes a very narrow wavelength band centered around a single wavelength. On the other hand, broadband laser light sources often generate laser light that includes a wide spectrum of wavelengths, often referred to as a continuum. One common method for generating a wide spectrum is to use a microstructure glass fiber, such as a photonic crystal fiber (PCF), in combination with a pulsed laser.
[0003] Broadband laser light sources are used as versatile excitation light sources in fluorescence microscopes. Typically, an acousto-optic tunable filter is used to select laser light that includes wavelengths from one or more spectral bands from a wide spectrum. The selected laser light is then directed onto a sample to excite fluorophores located within the sample. The optimal excitation wavelength for a particular fluorescent dye or protein can be easily selected from the wide spectrum of broadband laser light by adjusting the acousto-optic tunable filter. This results in high excitation efficiency and enables the acquisition of high-quality microscope images without causing stress to the sample, for example, by over-exciting the sample.
[0004] However, to maximize flexibility, the light source used in fluorescence microscopy needs to be able to excite multiple different fluorescent dyes and fluorescent proteins, each with a different excitation spectrum. Therefore, a broadband laser light source intended for use as an excitation source in fluorescence microscopy must be able to emit excitation light across the entire visible spectrum. However, generating such a broad spectrum from a single laser light source is extremely complex and therefore expensive. In particular, when generating short-wavelength laser light, the microstructured glass fibers typically used in broadband laser light sources are subjected to significant stress, resulting in a reduced lifetime. Consequently, broadband laser light sources often have no optical output or only insufficient optical output in the short-wavelength region of the visible spectrum, i.e., the blue spectral range of approximately 400 nm. [Overview of the Initiative] [Problems that the invention aims to solve]
[0005] Therefore, the objective is to provide a light source unit and method for an imaging device that provides a cost-effective means for generating laser light having a broad spectrum including the short wavelength region of the visible spectrum. [Means for solving the problem]
[0006] The objectives described above are achieved by the subject matter of each independent claim. Advantageous embodiments are defined in each dependent claim and in the following description.
[0007] The proposed light source unit for the imaging device includes a beam extraction unit configured to receive broadband laser light, direct at least a portion of the broadband laser light having a first wavelength to an amplified beam path, and direct the remaining laser light to a first illumination beam path. The light source unit also includes an optical amplifier unit located within the amplified beam path and configured to amplify the laser light having the first wavelength. The light source unit further includes a frequency changing unit located within the amplified beam path and configured to generate laser light having a second wavelength from the amplified laser light having the first wavelength.
[0008] A laser beam having a first wavelength is extracted from the broadband laser beam and directed to an amplifier beam path separate from the illumination beam path. In the amplifier beam path, the laser beam having the first wavelength is amplified. Next, the amplified laser beam is frequency-shifted from the first wavelength to the second wavelength. This configuration can be used to generate a laser beam having a second wavelength that lies outside the spectrum of the broadband laser beam. Thus, the proposed light source unit provides a means to extend the spectrum of the broadband laser beam, particularly to the short-wavelength region of the visible spectrum, i.e., the blue portion of the spectrum around 400 nm.
[0009] Therefore, since only one broadband laser light source is used and no additional laser light sources are required, the proposed light source unit is very cost-effective. The proposed light source unit can also be made very compact for the same reason. Short-wavelength laser light is generated outside the broadband laser light source. Therefore, the short-wavelength laser light does not damage the microstructured fibers typically used in such light sources, thereby extending the lifetime of the broadband laser light source. Furthermore, if the light source for the broadband laser light is pulsed, the laser light with a second wavelength is also synchronized with the remaining laser light. This is particularly important for fluorescence imaging applications based on fluorescence lifetime, and it makes it possible to use the light source unit for further applications, such as pulsed interleaved excitation microscopy.
[0010] In one embodiment, the frequency changing unit is configured to direct the laser light having a second wavelength to a second illumination beam path. In this embodiment, the light source unit includes two separate illumination beam paths. Furthermore, the versatility of the light source unit can be further enhanced because the remaining laser light and the laser light of the second wavelength can be used independently.
[0011] In another embodiment, the light source unit includes a beam integration unit configured to couple laser light having a second wavelength to the first illumination beam path. In this embodiment, the light source unit includes only one illumination beam path. Both the remaining laser light and the laser light having the second wavelength are coupled to a single beam of phase-locked laser light. The resulting single beam of excitation light has a broad spectrum and can be used to excite various different fluorescent dyes and / or fluorescent proteins.
[0012] In another embodiment, the light source unit comprises at least one acousto-optic tunable filter located within at least one of the first and second illumination beam paths. For example, the acousto-optic tunable filter may be located within a single illumination beam path following a beam integration unit. In such embodiments, the acousto-optic tunable filter can be used to select a specific excitation wavelength or wavelength band from the extended spectrum provided by the light source unit. This provides the light source unit with a highly flexible excitation source capable of exciting a number of different fluorophores. Such an excitation source can be used very advantageously, for example, in fluorescence microscopy, particularly scanning and / or confocal microscopy. It is also possible to place one acousto-optic tunable filter in each of the two illumination beam paths. An additional acousto-optic tunable filter in the second illumination beam path can be used to select whether or not to switch on laser light having a second wavelength, or to adjust the intensity of laser light having a second wavelength. Alternatively, the optical amplifier unit may be controlled so that laser light having a second wavelength is not generated.
[0013] In another embodiment, the beam extraction unit is configured to orient at least a portion of broadband laser light having a first polarization into an amplified beam path and to orient laser light having a second polarization into a first illumination beam path. This can be achieved, for example, by a polarizing beam splitter.
[0014] Alternatively or additionally, acousto-optic tunable filters filter light of a specific polarization (i.e., either s-polarized or p-polarized). Therefore, when using an acousto-optic tunable filter to select a specific excitation wavelength or wavelength band, light with the polarization filtered by the acousto-optic tunable filter cannot be used as excitation light, for example. In another form, unused laser light is extracted from broadband laser light and used to generate laser light with a second wavelength, thereby preventing waste of broadband laser light and making the light source unit more efficient. To combine the laser light with the second wavelength with the remaining laser light and return them together, the polarization of the laser light with the second wavelength needs to be changed, for example, by a waveplate, prism, or simple mirror configuration.
[0015] In another embodiment, the beam extraction unit includes an edge filter, particularly a short-pass filter. The edge filter blocks light having wavelengths above or below the central wavelength. In this embodiment, the beam extraction unit functions similarly to an edge filter, particularly a short-pass filter, in the sense that the beam extraction unit directs the majority of the broadband laser light having wavelengths above the central wavelength to the amplifier beam path. The remaining laser light, i.e., the majority of the broadband laser light having wavelengths below the central wavelength, is directed to a first illumination beam path. The edge filter can be implemented in particular by a beam splitting element, such as a dichroic beam splitter. Alternatively, a dedicated filter element may be placed between the beam splitting element and the optical amplifier unit. Both dichroic beam splitters and dedicated filter elements that function as edge filters are less expensive than, for example, acousto-optic tunable filters, thereby making the beam extraction unit more cost-effective.
[0016] In another embodiment, the beam extraction unit includes a bandpass having a center wavelength equal to the first wavelength. The bandpass is a filter that blocks all wavelengths of light outside the wavelength band near the center wavelength. In this embodiment, the beam extraction unit functions similarly to a bandpass filter in the sense that it directs most of the broadband laser light having wavelengths within the wavelength band centered on the center wavelength to the amplifier beam path. The bandpass can be implemented in particular by a beam splitting element, such as a dichroic beam splitter. Alternatively, a dedicated filter element may be placed between the beam splitting element and the optical amplifier unit. As in the embodiments described above, a dichroic beam splitter and a dedicated filter element that function as a bandpass filter are less expensive than, for example, an acousto-optic tunable filter, thereby making the beam extraction unit more cost-effective.
[0017] In another embodiment, the frequency changing unit is configured to perform a parametric process to generate laser light having a second wavelength from amplified light having a first wavelength. The parametric process uses nonlinear optical effects to achieve the wavelength shift from the first wavelength to the second wavelength. In particular, the parametric process is the generation of a second harmonic or a higher harmonic. During the generation of the second harmonic, the frequency of the amplified light doubles, i.e., the wavelength of the amplified light is halved. During the generation of a higher harmonic, the frequency of the amplified light changes by an integer coefficient. For example, during the generation of the third harmonic, the frequency triples, during the generation of the fourth harmonic, the frequency quadruples, and so on. The parametric process generates light of a shorter wavelength from the light extracted from the broadband laser light. This extends the spectrum of the broadband laser light toward the short-wavelength region, making the light source unit even more versatile.
[0018] In another embodiment, the frequency changing unit includes a first collimating lens, a nonlinear optical crystal, and a second collimating lens, the first collimating lens, the nonlinear optical crystal, and the second collimating lens arranged in this order within the amplifier beam path. The nonlinear optical crystal is preferably a lithium niobate crystal or a barium borate crystal with periodically reversed polarization. However, other types of crystals may be used as the nonlinear optical crystal. The nonlinear optical crystal is a passive optical element, meaning that it requires only a simple control circuit, at most including a Peltier element for temperature control, to function. Therefore, the frequency changing unit has a particularly simple design that makes the manufacture of the light source unit easier.
[0019] In another embodiment, the second wavelength has a value of 350 nm to 450 nm, particularly 380 nm to 420 nm. In this embodiment, the second wavelength is in the blue region of the visible spectrum, i.e., the short wavelength region. Laser light in this wavelength region is used in many fluorescence imaging applications, such as in biological experiments using DAPI as a fluorophore for staining cell nuclei. Since many broadband laser sources do not provide light in this wavelength region, and broadband laser sources that do provide light in this wavelength region are expensive, the light source unit according to this embodiment complements a significant gap and provides a cost-effective broadband laser source that can be used in a wide range of applications.
[0020] In another embodiment, the first wavelength has a value of 700 nm to 900 nm, particularly 760 nm to 840 nm. Many broadband laser sources provide laser light in the red and near-infrared regions. This light can be extracted, amplified, and then frequency-doubled to light in the 350 nm to 450 nm range, particularly 380 nm to 420 nm. As mentioned above, this wavelength range is important for many applications in fluorescence imaging.
[0021] In another embodiment, the light source unit includes a supercontinuous light source configured to generate broadband laser light and direct the broadband laser light to a beam extraction unit. A supercontinuous laser is typically a laser source that uses a microstructured glass fiber to generate broadband laser light from a pulsed laser source. Typically, the pulsed laser source has pulse lengths ranging from femtoseconds to picoseconds and emits light having near-infrared wavelengths. The broadband laser light generated by the supercontinuous laser has wavelengths both longer and shorter than the wavelength of the original pulsed laser light, also referred to as seed laser light. Because a supercontinuous light source uses a single pulsed seed laser source, it is more compact compared to a configuration that uses multiple different laser sources to generate broadband laser light or light having multiple single wavelengths. Therefore, by using a supercontinuous light source, the light source unit can also be made very compact.
[0022] In another embodiment, the light source unit includes an optical amplifier control unit. The supercontinuous light source is pulsed. The optical amplifier control unit is configured to set the parameters of the optical amplifier unit according to the pulse rate of the supercontinuous light source. By amplifying the extracted light of a first wavelength according to the pulse rate of the supercontinuous light source, the extracted light can be amplified more efficiently. This reduces the wasted portion of the extracted light, allowing more of the extracted light to be used, for example, to excite fluorophores. Thus, the light source unit becomes more efficient.
[0023] In another embodiment, the light source unit includes an optical amplifier control unit. The optical amplifier control unit is configured to set parameters of the optical amplifier unit according to the power of the supercontinuum light source. In this embodiment, by amplifying the extracted light of the first wavelength according to the power of the supercontinuum light source, the extracted light can be amplified more efficiently. As a result, the wasted portion of the extracted light is reduced, and for example, more of the extracted light can be used to excite the fluorophore. Also, damage to the optical amplifier unit can be prevented. Thus, the light source unit becomes more efficient.
[0024] The present invention also relates to an imaging device including the above-described light source unit. Preferably, the imaging device is a microscope, particularly a confocal microscope and / or a scanning microscope. The imaging device has the same effect as the above-described light source unit.
[0025] The present invention further relates to a method for generating laser light. The method includes receiving broadband laser light, directing at least a portion of the broadband laser light having a first wavelength into an amplifier beam path, directing the remaining laser light into a first illumination beam path, amplifying the light having the first wavelength, and generating light having a second wavelength from the amplified light having the first wavelength.
[0026] The method has the same advantages as the above-described light source unit and can be supplemented using the features of each dependent claim directed to the light source unit.
[0027] Specific embodiments will be described below with reference to the drawings.
Brief Description of the Drawings
[0028] [Figure 1] It is a schematic diagram of a light source unit for an imaging device according to an embodiment. [Figure 2] It is a schematic diagram of a light source unit according to another embodiment having two illumination beam paths. [Figure 3] This is a schematic diagram of a light source unit according to another embodiment having a polarizing beam splitter element. [Figure 4] This is a schematic diagram of a light source unit according to another embodiment, having a polarizing beam splitter element and a second illumination beam path. [Figure 5] This graph schematically shows the spectrum of broadband laser light. [Figure 6] This graph schematically shows the spectrum of amplified laser light. [Figure 7] This graph schematically shows the spectrum of the laser light generated by the frequency changing unit. [Figure 8] This is a schematic diagram of an imaging device according to one embodiment. [Modes for carrying out the invention]
[0029] Figure 1 is a schematic diagram of a light source unit 100 for an imaging device 800 according to one embodiment.
[0030] The light source unit 100 includes a broadband laser light source 102, exemplaryly formed as a supercontinuum light source configured to generate broadband laser light 104. The broadband laser light 104 includes laser light having a wide range of wavelengths in the visible spectrum and near-infrared, and may extend to infrared. An exemplary spectrum of the broadband laser light 104 is described below with reference to Figure 5. The broadband laser light source 102 is positioned and configured to emit broadband laser light 104 in the direction of the beam extraction unit 106. The beam extraction unit 106 extracts a portion of the broadband laser light 104 and directs the extracted portion of the broadband laser light 104 to the amplifier beam path 108. The remaining portion of the broadband laser light 104, i.e., the unextracted portion, is directed by the beam extraction unit 106 to the illumination beam path 110 and is hereafter referred to as the remaining laser light. The extracted portion of the broadband laser may include laser light having wavelengths from a narrow wavelength band centered on a first wavelength. In this case, the beam extraction unit 106 functions as a bandpass filter. The extracted portion of the broadband laser may also include laser light of all wavelengths above a specific wavelength, including a first wavelength. In this case, the beam extraction unit 106 functions as an edge filter. In either case, the extracted portion of the broadband laser includes laser light having a first wavelength.
[0031] The extracted portion of the broadband laser is directed to an optical amplifier unit 112 located within the amplifier beam path 108. The optical amplifier unit 112 is adapted to amplify the laser light having a first wavelength in order to generate amplified laser light. An example spectrum of the amplified laser light is described below with reference to Figure 6. The amplified laser light is then directed to a frequency changing unit 114 located within the amplifier beam path 108. The frequency changing unit 114 generates laser light of a second wavelength from the amplified laser light of the first wavelength. However, since the frequency changing unit 114 may not convert all the light having the first wavelength to light having the second wavelength, the laser light generated by the frequency changing unit 114 may contain both the first and second wavelengths. An example spectrum of the laser light generated by the frequency changing unit 114 is described below with reference to Figure 7.
[0032] In this embodiment, the laser light generated by the frequency changing unit 114 is then directed towards the beam integrating unit 116 located at the intersection of the first illumination beam path 110 and the amplifier beam path 108. The beam integrating unit 116 combines the remaining light with the laser light generated by the frequency changing unit 114 by combining it and returning it to the illumination beam path 110, thereby forming a combined laser beam.
[0033] The acousto-optic tunable filter 118 is located in the illumination beam path 110 after the beam integration unit 116. The acousto-optic tunable filter 118 can be used to filter one or more spectral bands from the coupled laser light to generate excitation light that can be directed toward the sample 808 (see Figure 8) to excite fluorophores located within the sample 808 (see Figure 8).
[0034] Figure 2 is a schematic diagram of a light source unit 200 according to another embodiment.
[0035] The light source unit 200 shown in Figure 2 is distinguished from the light source unit 100 shown in Figure 1 by having a second illumination beam path 202. The second illumination beam path 202 starts after the frequency changing unit 114 and includes a second acousto-optic tunable filter 204. The second acousto-optic tunable filter 204 is used to control the intensity of the laser light generated by the frequency changing unit 114 before the laser light is emitted by the light source unit 200, for example, before it is used as excitation light. In this embodiment, the light source unit 200 does not include a beam integration unit 116. The first acousto-optic tunable filter 118 is located immediately after the beam extraction unit 106 in the first illumination beam path 110.
[0036] Figure 3 is a schematic diagram of a light source unit 300 according to another embodiment.
[0037] The broadband laser light 104 is typically unpolarized, meaning that all polarizations are present in the broadband laser light 104. The first acousto-optic tunable filter unit 118 filters out all laser light that has either s-polarization or p-polarization. This means that only about half of the broadband laser light 104 is available with the light source unit 100 according to Figure 1. Therefore, the light source unit 300 according to Figure 3 is distinguished from the light source unit 100 according to Figure 1 in that the beam extraction unit 302 extracts laser light from the broadband laser light based on its polarization.
[0038] According to this embodiment, the beam extraction unit 302 includes a beam splitting element 304 configured to direct laser light having a first polarization towards the amplifier beam path 108 and laser light having a second polarization towards the first illumination beam path 110. The beam extraction unit 302 further includes a filter element 306 disposed in the amplifier beam path 108 between the beam splitting element 304 and the optical amplifier unit 112. The filter element 306 is an optional means and may be a bandpass configured to filter all wavelengths except a narrowband centered on a first wavelength. Alternatively, the filter element 306 may be an edge filter configured to filter laser light of all wavelengths below a specific wavelength. The filter element 306 is used to filter wavelengths other than the first wavelength in order to adapt the extracted portion of the broadband laser to the amplification profile of the optical amplifier unit 112.
[0039] In this embodiment, the beam integration unit 308 may include a polarization changing element, such as a waveplate, configured to change the polarization of the laser light generated by the frequency changing unit 114 to a second polarization, i.e., the polarization of the remaining laser light. This ensures that the laser light generated by the frequency changing unit 114 is not filtered by the first acousto-optic tunable filter 118 and is therefore available to the light source unit 300.
[0040] Figure 4 is a schematic diagram of a light source unit 400 according to another embodiment.
[0041] The light source unit 400 shown in Figure 4 is distinguished from the light source unit 300 shown in Figure 3 by having a second illumination beam path 202. In other words, the light source unit 400 shown in Figure 4 is a combination of the light source unit 200 shown in Figure 2 and the light source unit 300 shown in Figure 3. The second illumination beam path 202 includes a second acousto-optic tunable filter 204. In this embodiment, the first acousto-optic tunable filter 118 is configured not to filter laser light having the second polarization, i.e., the polarization of the remaining laser light, and the second acousto-optic tunable filter 204 is configured not to filter laser light having the first polarization, i.e., the polarization of the laser light generated by the frequency changing unit 114.
[0042] Figure 5 is a graph 500 that schematically shows the spectrum of broadband laser light 104.
[0043] In Graph 500, the horizontal coordinate 502 represents the wavelength in nm. The vertical coordinate 504 represents the intensity. The exemplary spectrum of broadband laser light 104 shown in Figure 5 includes wavelengths from the blue region of the visible spectrum at approximately 450 nm to the near-infrared region at approximately 850 nm. The intensity of broadband laser light 104 is highest in the region from approximately 520 nm to approximately 750 nm. There is a prominent peak 506 in intensity around 520 nm. Below wavelengths of approximately 520 nm, the intensity drops sharply to zero, and there is almost no intensity in the blue region of the visible spectrum from approximately 400 nm to approximately 450 nm.
[0044] Figure 6 is a graph 600 that schematically shows the spectrum of the amplified laser light.
[0045] In graph 600, the horizontal coordinate 602 represents the wavelength in nm. The vertical coordinate 604 represents the intensity. The exemplary spectrum of the amplified laser light, i.e., the laser light amplified by the optical amplifier unit 112, includes a narrowband 606 centered on a first wavelength, which in this embodiment is exemplary selected to be 785 nm.
[0046] Figure 7 is a graph 700 that schematically shows the spectrum of the laser light generated by the frequency changing unit 114.
[0047] In graph 700, the horizontal coordinate 702 represents the wavelength in nm. The vertical coordinate 704 represents the intensity. The exemplary spectrum of the laser light produced by the frequency changing unit 114 includes two narrowbands 706 and 708. The first band 706, shown on the right side of Figure 7, includes wavelengths centered on a first wavelength. The second band 708, shown on the left side of Figure 7, includes wavelengths centered on a second wavelength, which in this embodiment is exemplary selected to be 392.5 nm, or exactly half of the first wavelength. In other words, the frequency changing unit 114 according to this embodiment performs frequency doubling.
[0048] As can be seen from Graph 700 shown in Figure 7, the intensity of the laser light with the second wavelength is lower than the intensity of the laser light with the first wavelength. This is because the frequency conversion unit 114 does not convert all of the laser light of the first wavelength to laser light of the second wavelength. There are limits to the efficiency of wavelength conversion.
[0049] Referring to Figures 5 to 7, the first and second wavelengths in the embodiments described above are selected so that the spectrum of the broadband laser light 104 is extended by light in the blue spectral region of approximately 400 nm. Laser light in this spectral region is costly to generate using known broadband laser sources, but is nevertheless important for certain fluorescence imaging applications, such as fluorescence imaging including DAPI, which is typically used to image cell nuclei.
[0050] Figure 8 is a schematic diagram of an imaging device 800 according to one embodiment.
[0051] The imaging device 800 is exemplary formed as a microscope. More specifically, the imaging device 800 is formed as a fluorescence microscope configured to image a sample 808 by fluorescence imaging.
[0052] The imaging device 800 includes one of the light source units 100, 200, 300, and 400, which are referred to above with reference to Figures 1 to 7 and commonly referred to by reference numeral 802 in Figure 8. The light source unit 802 is configured to emit excitation light to the illumination beam path 804 of the imaging device 800 in order to excite fluorophores located within the sample 808.
[0053] The optical detection system 806 of the imaging device 800 is configured to generate an image of the sample 808 based on fluorescence emitted by excited fluorophores. The optical detection system 806 according to this embodiment includes an objective lens 810 oriented toward the sample 808 and a detector element 812. The objective lens 810 receives fluorescence emitted by excited fluorophores and directs the fluorescence toward the detection beam path 814. The beam splitter 816 is positioned at the intersection of the illumination beam path 804 and the detection beam path 814, which are shown exemplary to be perpendicular to each other in this embodiment. The beam splitter 816 is configured so that the excitation light is directed toward the sample 808 via the objective lens 810. The beam splitter 816 is further configured so that the fluorescence received by the objective lens 810 is directed toward the detector element 812.
[0054] The imaging system further comprises a control unit 818 connected to an optical detection system 806 and a light source unit 802. The control unit 818 is configured to control the optical detection system 806 and the light source unit 802, for example, based on user input. The control unit 818 according to this embodiment includes an optical amplifier control unit 820 configured to control the optical amplifier unit 112 of the light source unit 802.
[0055] Furthermore, although the explanation used the example where the imaging device 800 is a microscope, the imaging device 800 may be any other imaging device. In particular, the imaging device 800 may be any imaging device configured for fluorescence imaging.
[0056] Elements that function identically or similarly are indicated by the same reference numerals in all figures. As used herein, the term “and / or” includes all combinations of one or more items from the related descriptions and may be abbreviated as “ / ”. It is considered that all individual features of the embodiments and all combinations of the individual features of the embodiments with each other, as well as combinations with the individual features or sets of features of the foregoing description and / or claims, are disclosed.
[0057] While several embodiments have been described in the context of the apparatus, it is clear that these embodiments also represent descriptions of the corresponding methods, where blocks or apparatus correspond to steps or features of steps. Similarly, embodiments described in the context of steps also represent descriptions of the corresponding blocks, items, or features of the corresponding apparatus. [Explanation of Symbols]
[0058] 100 light source units 102 Broadband laser light source 104 Broadband laser light 106 Beam Extraction Unit 108 Amplifier beam path 110 Lighting beam path 112 Optical Amplifier Unit 114 Frequency Change Unit 116 Beam Integration Unit 118 Acousto-optic wavelength tunable filter 200 light source units 202 Lighting beam path 204 Acousto-optical wavelength tunable filter 300 light source units 302 Beam Extraction Unit 304 Beam splitting element 306 filter elements 308 Beam Integration Unit 400 light source units 500 graphs 502 horizontal coordinate 504 Vertical coordinate 506 Peak 600 spectra 602 horizontal coordinate 604 Vertical coordinate 606 bandwidth 700 spectrum 702 horizontal coordinate 704 Vertical coordinate 706,708 bandwidth 800 imaging devices 802 Light source unit 804 Illumination beam path 806 Optical detection system 808 samples 810 Objective Lens 812 Detector elements 814 Detection beam path 816 Beam Splitter 818 Control Unit 820 Optical Amplifier Control Unit
Claims
1. A light source unit (100, 200, 300, 400) for an imaging device (800), wherein the light source unit (100, 200, 300, 400) is A beam extraction unit (106, 302) is configured to receive broadband laser light (104), direct at least a portion of the broadband laser light (104) having a first wavelength towards an amplifier beam path (108), and direct the remaining laser light towards a first illumination beam path (110), An optical amplifier unit (112) is disposed within the amplifier beam path (108) and configured to amplify the laser light having the first wavelength, A frequency changing unit (114) is disposed within the amplifier beam path (108) and configured to generate a laser light having a second wavelength from the amplified laser light having a first wavelength, Light source units (100, 200, 300, 400) equipped with the following.
2. The frequency changing unit (114) is configured to direct the laser light having the second wavelength towards the second illumination beam path (202). The light source unit (200, 400) according to claim 1.
3. The light source unit (100, 300) includes a beam integration unit (116, 308) configured to couple the laser light having the second wavelength to the first illumination beam path (110). The light source unit (100, 300) according to claim 1.
4. The light source unit (100, 200, 300, 400) includes at least one acousto-optic tunable filter (118, 204) located within at least one of the first illumination beam path (110) and the second illumination beam path (202). The light source unit (100, 200, 300, 400) according to claim 1.
5. The beam extraction unit (302) is configured to direct at least a portion of the broadband laser light (104) having a first polarization towards the amplifier beam path (108) and to direct the laser light having a second polarization towards the first illumination beam path (110). The light source unit (300, 400) according to claim 1.
6. The beam extraction unit (106, 302) is equipped with an edge filter, in particular a short-pass filter. The light source unit (100, 200, 300, 400) according to claim 1.
7. The beam extraction unit (106, 302) is equipped with a bandpass having a center wavelength equal to the first wavelength. The light source unit (100, 200, 300, 400) according to claim 1.
8. The frequency changing unit (114) is configured to perform a parametric process to generate laser light having the second wavelength from amplified light having the first wavelength. The light source unit (100, 200, 300, 400) according to claim 1.
9. The parametric process is the generation of a second harmonic or a higher-order harmonic. The light source unit (100, 200, 300, 400) according to claim 8.
10. The frequency changing unit (114) includes a first collimating lens, a nonlinear optical crystal, and a second collimating lens, wherein the first collimating lens, the nonlinear optical crystal, and the second collimating lens are arranged in this order within the amplifier beam path (108), and the nonlinear optical crystal is preferably a lithium niobate crystal or a barium borate crystal with periodically reversed polarization. The light source unit (100, 200, 300, 400) according to claim 9.
11. The second wavelength has a value of 350 nm to 450 nm, particularly a value of 380 nm to 420 nm. The light source unit (100, 200, 300, 400) according to claim 1.
12. The first wavelength has a value between 700 nm and 900 nm, particularly between 760 nm and 840 nm. The light source unit (100, 200, 300, 400) according to claim 1.
13. The light source units (100, 200, 300, 400) include a supercontinuum light source (102) configured to generate broadband laser light (104) and direct the broadband laser light (104) toward the beam extraction units (106, 302). The light source unit (100, 200, 300, 400) according to claim 1.
14. The light source units (100, 200, 300, 400) include an optical amplifier control unit (820), the supercontinuous light source (102) is pulsed, and the optical amplifier control unit (820) is configured to set the parameters of the optical amplifier unit (112) according to the pulse rate of the supercontinuous light source (102). The light source unit (100, 200, 300, 400) according to claim 13.
15. The light source units (100, 200, 300, 400) include an optical amplifier control unit (820), which is configured to set the parameters of the optical amplifier unit (112) according to the power of the supercontinuum light source (102). The light source unit (100, 200, 300, 400) according to claim 13.
16. An imaging device (800) comprising a light source unit (100, 200, 300, 400) according to any one of claims 1 to 15.
17. A method for generating laser light, wherein the method is a) A step of receiving broadband laser light (104), b) The steps of directing at least a portion of the broadband laser light (104) having a first wavelength towards the amplifier beam path (108) and directing the remaining laser light towards the first illumination beam path (110), c) A step of amplifying light having the first wavelength, d) A step of generating light having a second wavelength from amplified light having the first wavelength, A method that includes this.