JP2020106535A - Fluorescence detection optical device - Google Patents

Abstract

To provide a small fluorescence detection optical device with high detection sensitivity.SOLUTION: A fluorescence detection optical device 10 irradiates a sample S with excitation light EL and detects fluorescence FL generated by the irradiation from the sample S. The fluorescence detection optical device 10 comprises: a first lens group 20 that directly receives the fluorescence FL generated from the sample S; a second lens group 22 which is arranged coaxially with the first lens group 20 and includes a gap part formed by cutting a part thereof outside the axis; and an excitation light optical system 24 which emits the excitation light EL. The excitation light optical system 24 is arranged so that the emitted excitation light EL transmits through an off-axis portion 20a of the first lens group 20 and hits the sample S. In the fluorescence detection optical device 10, a part of the excitation light optical system 24 is arranged in the gap part 30.SELECTED DRAWING: Figure 2

Description

The present invention relates to an optical device for fluorescence detection, which irradiates an object to be detected with excitation light and detects the fluorescence generated by the object to be detected.

In recent years, many optical devices for fluorescence detection have begun to be used in the field of life science. Since an optical device for fluorescence detection is simple and has high detection sensitivity, it is sometimes used in combination with an amplification step to effectively detect nucleic acids such as DNA labeled with a fluorescent chemical substance.

For example, the photodetector disclosed in Patent Document 1 guides a laser beam through a first optical waveguide, collects the laser beam with a first lens, and irradiates a specimen substantially obliquely from above with an irradiation optical system and excitation with the irradiation light. And a light receiving optical system that collects the fluorescence from the sample with the second lens and guides it to the measuring instrument with the second optical waveguide. In this photodetector, the irradiation optical system and the light receiving optical system are separate light guide paths.

International Publication No. 2007/091530

However, the fluorescence detecting optical device in which the irradiation optical system and the light receiving optical system are separate as in Patent Document 1 has the following problems.

FIG. 1 shows an example of a conventional fluorescence detection optical device. The optical device 100 for fluorescence detection shown in FIG. 1 focuses the irradiation optical system 102 for irradiating the sample S in the container C with the excitation light EL, and the fluorescence FL generated from the sample S at the fluorescence focusing point 103. And a light receiving optical system 104 for. The irradiation optical system 102 includes an excitation light source 106 and an excitation light lens 108 that focuses the excitation light EL on the sample S. The light receiving optical system 104 includes an objective lens 110, and collects the fluorescence FL emitted from the fluorescence emission point 101 on the sample S at a fluorescence concentration point 103 that is conjugate with the fluorescence emission point 101. As shown in FIG. 1, the optical axis 112 of the irradiation optical system 102 is inclined with respect to the optical axis 114 of the light receiving optical system 104 (the optical axis 112 of the excitation light EL and the optical axis 114 of the light receiving optical system 104. The angle formed by is θi).

In the fluorescence detecting optical device 100 configured as shown in FIG. 1, in order to improve the detection sensitivity, it is necessary to incorporate more fluorescence FL into the light receiving optical system 104. For that purpose, it is necessary to increase the numerical aperture (NA) of the light receiving optical system 104, but there is a limit in the fluorescence detection optical device 100. This can be achieved by increasing the size of the objective lens 110 in order to increase the NA of the light receiving optical system 104, but if the size of the objective lens 110 is too large, the excitation light EL emitted at the angle θi interferes with the objective lens 110. This is because.

Further, when trying to avoid the interference between the excitation light EL and the objective lens 110 while ensuring a sufficient NA of the light receiving optical system 104, the excitation light source is located at a position away from the sample S or at a position where the angle θi increases. 106 and the lens 108 for excitation light must be arranged. In this case, it becomes difficult to downsize the fluorescence detecting optical device 100.

Further, particularly when the container C has a deep bottom as shown in FIG. 1, the excitation light EL may be blocked by the side wall of the container C when the angle θi is large. In this case, the sample S located at the bottom of the container C cannot be irradiated with sufficient excitation light EL, and as a result, fluorescence may not be detected from the sample S.

The present invention has been made in view of such circumstances, and an object thereof is to provide a compact fluorescence detection optical device with high detection sensitivity.

In order to solve the above problems, an optical device for fluorescence detection according to an aspect of the present invention irradiates an object to be detected with excitation light and detects fluorescence generated from the object to be detected by the irradiation. This fluorescence detection optical device includes a first lens group that directly receives fluorescence generated from an object to be detected, and a second lens group that is arranged coaxially with the first lens group and that receives fluorescence that has passed through the first lens group. And a second lens group in which a part of the off-axis is cut off to form a void portion, and an excitation light optical system for emitting excitation light, wherein the emitted excitation light is off-axis of the first lens group. And an excitation light optical system arranged to irradiate the object to be detected. In this fluorescence detecting optical device, a part of the excitation light optical system is arranged in the void portion of the second lens group.

The first lens group may collimate the fluorescence generated from the object to be detected into parallel light. The second lens group may collect the parallel light of fluorescence from the first lens group.

The void portion may be formed on the peripheral portion of the second lens group.

The pumping light optical system may include a pumping light source that emits pumping light, and a pumping light lens group that collimates the pumping light from the pumping light source and makes it enter off-axis of the first lens group.

The excitation light source may include a light emitting element that emits excitation light.

The excitation light source may include an emission end face of an excitation light optical fiber that guides the excitation light.

The excitation light source may include a light emitting element provided in the image side space of the second lens group. The excitation light lens group may include a relay lens system arranged to form an intermediate image of the light emitting region of the light emitting element in the void portion.

A plurality of excitation light optical systems may be provided. A plurality of void portions may be formed in the second lens group, and a part of the excitation light optical system may be arranged in each of the plurality of void portions.

According to the present invention, it is possible to provide an optical device for fluorescence detection which has a high detection sensitivity and a small size.

It is a figure which shows an example of the conventional optical device for fluorescence detection. It is a figure for explaining the optical device for fluorescence detection concerning this embodiment. 3A to 3C are views for explaining the shape and size of the void portion formed in the second lens group. It is a figure for explaining the optical device for fluorescence detection concerning the 1st example. It is a figure for demonstrating the fluorescence detection optical apparatus which concerns on 2nd Example. It is a figure for demonstrating the fluorescence detection optical apparatus which concerns on 3rd Example. It is a figure for demonstrating the fluorescence detection optical device which concerns on another embodiment of this invention. FIG. 8 is a diagram showing a plan view of the second lens group as seen from the optical axis direction in the fluorescence detecting optical device shown in FIG. 7.

Hereinafter, the fluorescence detection optical device according to the embodiment of the present invention will be described. The same or equivalent constituent elements, members, and processes shown in each drawing are denoted by the same reference numerals, and duplicated description will be omitted as appropriate. Further, the embodiments are merely examples and do not limit the invention, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

FIG. 2 is a diagram for explaining the fluorescence detection optical device 10 according to the present embodiment. The fluorescence detection optical device 10 irradiates the sample S as the object to be detected with excitation light and detects the fluorescence generated from the sample S by the irradiation. The sample S is contained in the container C.

As shown in FIG. 2, the fluorescence detection optical device 10 includes an irradiation optical system 12 for irradiating the sample S in the container C with the excitation light EL, and a light reception for collecting the fluorescence FL generated from the sample S. And an optical system 14. The fluorescence detecting optical device 10 may include a holding member (not shown) for integrally holding the irradiation optical system 12 and the light receiving optical system 14. The fluorescence detecting optical device 10 in which the irradiation optical system 12 and the light receiving optical system 14 are thus integrated is also referred to as an “optical head”.

The light receiving optical system 14 condenses the fluorescence FL emitted from the fluorescence emission point 11 on the sample S to a fluorescence condensing point 13 that is conjugate with the fluorescence emission point 11. The light receiving optical system 14 directly receives the fluorescent light FL generated from the fluorescent light emission point 11 on the sample S and converts it into parallel light, and the parallel light of the fluorescent light FL that has passed through the first lens group 20. The second lens group 22 receives the light and focuses it on the fluorescence converging point 13. In this specification, the “lens group” refers to one or a plurality of lenses. In the present specification, in the light receiving optical system 14, the space in which the sample S is located is the object side space, the space in which the image of the sample S is formed by the light receiving optical system 14 is the image side space, Is designated by the term "object side" or "image side". In this case, the fluorescence emission point 11 substantially coincides with the object-side focal point of the first lens group 20, and the fluorescence condensing point 13 substantially coincides with the image-side focal point of the second lens group 22.

By configuring the light receiving optical system 14 using the first lens group 20 and the second lens group 22 in this way, the conjugate length can be easily adjusted, and the lens barrel length of the optical head can be easily set. Such a configuration is also advantageous for reducing aberrations. The second lens group 22 is preferably arranged coaxially with the first lens group 20. In this case, the aberration due to the lens system can be reduced, and the efficiency of focusing on the fluorescent light focusing point 13 can be improved. The first lens group 20 and the second lens group 22 do not have to have the same specifications.

The irradiation optical system 12 includes an excitation light optical system 24 that emits the excitation light EL, and an off-axis portion 20a of the first lens group 20 that refracts the excitation light EL from the excitation light optical system 24 and focuses it on the sample S. Composed of. The excitation light optical system 24 is arranged on the image side of the first lens group 20. The excitation light optical system 24 is arranged so that the emitted excitation light EL passes through the off-axis portion 20a of the first lens group 20 and is condensed at the fluorescence emission point 11 of the sample S. The optical axis 19 of the excitation light EL that enters the fluorescence emission point 11 is inclined with respect to the optical axis 17 of the first lens group 20 (the optical axis 19 of the excitation light EL and the optical axis 17 of the light receiving optical system 14). The angle formed by is θi).

The excitation light optical system 24 includes an excitation light source 16 that emits the excitation light EL, and an excitation light lens group 25 that makes the excitation light EL from the excitation light source 16 parallel light and makes it enter the off-axis portion 20 a of the first lens group 20. Composed of and. The excitation light lens group 25 is arranged such that its optical axis 21 is parallel to the optical axis 17 of the first lens group 20. As a result, the excitation light EL that has passed through the off-axis portion 20a of the first lens group 20 can be condensed at the fluorescence emission point 11 (that is, the object-side focus of the first lens group 20).

In the fluorescence detecting optical device 10 according to the present embodiment, the off-axis part of the second lens group 22 is cut off to form the void portion 30. Then, the excitation light source 16 which is a part of the excitation light optical system 24 is arranged in the void portion 30. The excitation light lens group 25 of the excitation light optical system 24 is arranged between the first lens group 20 and the second lens group 22.

In the fluorescence detecting optical device 10 configured as described above, the excitation light EL emitted from the excitation light source 16 is collimated by the excitation light lens group 25, and then the off-axis portion of the first lens group 20. The light passes through 20a and enters the fluorescence emission point 11 of the sample S at an angle θi. The fluorescence FL generated at the fluorescence emission point 11 of the sample S is taken into the first lens group 20 and made into parallel light, and then is condensed at the fluorescence condensing point 13 by the second lens group 22. By placing the light receiving surface of a light receiving element such as a PD (Photodiode) at the fluorescence condensing point 13, the fluorescence FL generated in the sample S can be detected.

In the fluorescence detecting optical device 10 according to the present embodiment, the excitation light EL is focused on the sample S by utilizing the off-axis portion 20a of the first lens group 20 that defines the NA of the light receiving optical system 14. In other words, the irradiation optical system 12 is arranged in the light receiving optical system 14. According to this configuration, unlike the fluorescence detecting optical device 100 described with reference to FIG. 1, even if the first lens group 20 is enlarged, the first lens group 20 and the excitation light EL do not interfere with each other. In other words, the NA of the light receiving optical system 14 is not limited by the presence of the irradiation optical system 12. Therefore, according to the fluorescence detecting optical device 10 of the present embodiment, since the NA of the light receiving optical system 14 can be increased, a large amount of fluorescence can be taken into the light receiving optical system 14, and as a result, fluorescence The detection sensitivity of can be improved.

Further, in the fluorescence detecting optical device 10 according to the present embodiment, the off-axis part of the second lens group 22 is cut off to form the void portion 30, and the excitation light optical system 24 is partly formed in the void portion 30. (Here, the excitation light source 16) is arranged. If a second lens group in which no void portion is formed is used, in order to dispose the excitation light optical system between the first lens group and the second lens group, the distance between the first lens group and the second lens group is required. Therefore, it becomes difficult to reduce the size of the fluorescence detection optical device. As in this embodiment, the gap between the first lens group 20 and the second lens group 22 is narrowed by arranging a part of the excitation light optical system 24 in the void portion 30 of the second lens group 22. Therefore, the fluorescence detection optical device 10 can be downsized. Further, since there is a margin in the arrangement of the excitation light optical system 24, it is possible to easily assemble the fluorescence detection optical device 10.

In the present embodiment, the excitation light source 16 is arranged in the void portion 30 of the second lens group 22, but in the void portion 30 another element of the excitation light optical system 24, for example, the excitation light lens group 25 and the excitation light source 16 is provided. Required power supply lines, mechanical arrangements for holding the pump light source 16, etc. may be arranged.

Further, in the fluorescence detecting optical device 10 according to the present embodiment, the irradiation optical system 12 is arranged in the light receiving optical system 14, so that the optical axis 19 of the excitation light EL and the optical axis 17 of the light receiving optical system 14 are provided. The angle θi formed by can be set small. This makes it difficult for the side wall of the container C to block the excitation light EL even when the container C has a deep bottom as shown in FIG. 2. As a result, the sample S located at the bottom of the container C can be irradiated with sufficient excitation light EL, so that the amount of fluorescence generated from the sample S is increased and the fluorescence detection sensitivity can be improved. The light receiving optical system and the excitation light optical system are not limited to the present embodiment in which parallel light is formed in the middle of the lens system, and by appropriately designing these optical systems, the light receiving optical system 14 In the case where the irradiation optical system 12 is configured to be installed in the case where the angle θi formed by the optical axis of the excitation light EL and the optical axis of the light receiving optical system 14 can be set small, Needless to say, the same effects as those of the present invention can be obtained.

FIGS. 3A to 3C are views for explaining the shape and size of the void portion 30 formed in the second lens group 22. 3A to 3C are plan views of the second lens group 22 viewed from the optical axis direction. 3A to 3C, the excitation light lens group 25 is also shown.

FIG. 3A shows a void portion 30 formed by cutting the off-axis portion of the second lens group 22 into a cuboid shape. The void portion 30 shown in FIG. 3A is formed to have substantially the same size as the excitation light lens group 25. FIG. 3B shows a void portion 30 formed by cutting off the off-axis portion of the second lens group 22 with a plane parallel to the optical axis. The void portion 30 shown in FIG. 3B is formed larger than the excitation light lens group 25. FIG. 3C shows the void portion 30 formed by punching the off-axis portion of the second lens group 22. The void portion 30 shown in FIG. 3C is formed smaller than the excitation light lens group 25.

3A to 3C show an example of the shape and size of the void portion 30, and of course, the shape and size of the void portion 30 are limited to the shapes shown in FIGS. 3A to 3C. Not done. The shape and size of the void portion 30 depends on the shape and size of the elements arranged in the void portion 30. Since the fluorescence that has entered the void portion 30 is lost without being focused on the fluorescent light focusing point 13, it is preferable that the size of the void portion 30 is set to a necessary minimum.

A part or all of the lenses forming the excitation light lens group 25 may be ball lenses. As for the excitation light lens group 25, the smaller the diameter and the width, the better. However, small-diameter lenses are often expensive in general. In that respect, ball lenses are relatively inexpensive and are mass-produced, and there is an advantage in that a ball lens made of a material having various refractive indexes and transmission characteristics and a lens having a small diameter are easily available.

The void portion 30 is preferably formed on the peripheral portion of the second lens group 22. This is because the amount of fluorescence taken in by the light receiving optical system 14 per unit area of the lens is usually larger as it is closer to the optical axis. By forming the void portion 30 in the peripheral portion where the light amount density is lower than that near the optical axis, more fluorescence can be condensed at the fluorescence condensing point 13 and the fluorescence detection sensitivity can be improved.

Next, an embodiment of the fluorescence detecting optical device 10 will be described.

FIG. 4 is a diagram for explaining the fluorescence detection optical device 40 according to the first example. The fluorescence detecting optical device 40 shown in FIG. 4 includes a light emitting element 42. The light emitting element 42 is arranged such that at least a part thereof is located in the void portion 30 of the second lens group 22. In the first embodiment, the light emitting element 42 can be regarded as the excitation light source 16 of the fluorescence detecting optical device 10 shown in FIG. As the light emitting element 42, an LED (Light-Emitting Diode), an LD (Laser Diode), or the like that includes a wavelength suitable for exciting the sample S in an emission band can be used.

Further, in the first embodiment, the fluorescence collected by the light receiving optical system 14 enters the fluorescence fiber 44 from the incident end face 44a and is guided to the light receiving unit 46. The light receiving unit 46 is arranged apart from the light receiving optical system 14. In the first embodiment, the incident end face 44a of the fluorescence fiber 44 can be regarded as the fluorescence converging point 13 of the fluorescence detecting optical device 10 shown in FIG.

As the fluorescent fiber 44, a single mode fiber or a multimode fiber can be used. The light receiving unit 46 includes a photoelectric conversion element that photoelectrically converts fluorescence, and an electric circuit that performs a predetermined process such as amplification on an electric signal. As the photoelectric conversion element, PD (Photodiode), APD (Avalanche Photodiode), PMT (Photomultiplier Tube), or the like can be used.

FIG. 5 is a diagram for explaining a fluorescence detection optical device 50 according to the second embodiment. The fluorescence detection optical device 50 shown in FIG. 5 includes a light source unit 52 which is arranged apart from the excitation light optical system 24, and an excitation light fiber 54 which guides the excitation light emitted from the light source unit 52. ..

The light source unit 52 includes a light source such as an LED, an LD, and a xenon lamp, and an electric circuit for supplying power to the light source. As the pumping light fiber 54, a single mode fiber or a multimode fiber can be used.

In the second embodiment, the emission end face 54a of the excitation light fiber 54 is arranged in the void portion 30 of the second lens group 22, and the excitation light emitted from the emission end face 54a of the excitation light fiber 54 is It is incident on the excitation light lens group 25. In the second embodiment, the emission end face 54a of the excitation light fiber 54 can be regarded as the excitation light source 16 of the fluorescence detecting optical device 10 shown in FIG.

According to the fluorescence detecting optical device 50 in the second example, a portion including only an optical system such as a lens and an optical fiber (that is, an “optical head”), an electric circuit, and a photoelectric conversion type light emitting/receiving element. Can be a separate body. According to the configuration of the second embodiment, the following operational effects can be obtained.
(A) The exit end face 54a of the excitation light fiber 54 is used as the excitation light source, and the entrance end face 44a of the fluorescence fiber 44 is used as the fluorescence focusing point. Since the diameter of the optical fiber is usually 1 mm or less, the optical head can be made smaller than when the photoelectric conversion type light emitting/receiving element itself is mounted on the optical head.
(B) Since the electric circuit and the light emitting/receiving element that easily generate electrical noise are separated from the optical head, the influence of noise can be suppressed. Since the electrical system, which is easily affected by noise due to disturbance, is separate from the optical head, the measurement environment is not limited.
(C) Monochromaticity is required in the field of fluorescence detection. In that case, by mounting a predetermined filter on a separate light source/light receiving unit, the desired level can be easily adjusted, and the degree of freedom in design specifications increases.
(D) Since the void portion 30 may be provided in the second lens group 22 to such an extent that the tip of an optical fiber having a diameter of 1 mm or less can be normally arranged, the excision region of the second lens group 22 can be set smaller. , The amount of fluorescence detected can be increased.

FIG. 6 is a diagram for explaining the fluorescence detecting optical device 60 according to the third embodiment. The excitation light optical system 24 of the optical device 60 for fluorescence detection shown in FIG. 6 includes a light emitting element 42 provided on the image side of the second lens group 22 and the excitation light from the light emitting element 42 to be parallel light for the first lens. And a relay lens system 62 which is incident on the off-axis portion 20a of the group 20. The relay lens system 62 is composed of a first lens 62a and a second lens 62b arranged so as to sandwich the second lens group 22 therebetween. The relay lens system 62 forms an intermediate image 64 of the light emitting area of the light emitting element 42 in the void portion 30 of the second lens group 22.

In the fluorescence detecting optical device 40 (see FIG. 4) according to the first example described above, at least a part of the light emitting element 42 is arranged in the void portion 30 of the second lens group 22. However, for example, when a bullet LED is used as the light emitting element 42, since the outer diameter thereof is about 3 mm, the void portion 30 tends to be large, and the amount of fluorescent light that can be collected may decrease. Therefore, the present inventor pays attention to the fact that the light emitting area of the LED is as small as 0.3×0.3 mm ² , and the relay lens system 62 is used to fill the void portion 30 with an intermediate light emitting area of the light emitting element 42. I thought about making a statue. According to the fluorescence detecting optical device 60 in the third example, the void portion 30 of the second lens group 22 can be made small, and the detected fluorescence amount can be increased.

FIG. 7 is a diagram for explaining a fluorescence detecting optical device 70 according to another embodiment of the present invention. FIG. 8 is a plan view of the second lens group 22 in the fluorescence detecting optical device 70 shown in FIG. 7 as seen from the optical axis direction.

The fluorescence detection optical device 70 according to the present embodiment includes four excitation light optical systems 24. Further, four void portions 30 are formed at 90° intervals on the peripheral portion of the second lens group 22. The pumping light source 16 which is a part of the pumping light optical system 24 is arranged in each of these four void portions 30. Although the hollow portion 30 having a square shape is shown in FIG. 8, the shape of the void portion 30 is not particularly limited.

In the fluorescence detecting optical device 70 according to the present embodiment, the four excitation light optical systems 24 can be optical systems having the same optical characteristics such as wavelength. In this case, the amount of excitation light can be increased, and it becomes possible to generate fluorescence at a detectable level even for a sample having a small absolute fluorescence emission amount.

Alternatively, the four excitation light optical systems 24 may be optical systems having mutually different optical characteristics such as wavelength. By detecting the fluorescence emitted from the sample by irradiating the excitation light of different wavelengths, it becomes possible to analyze the sample in a more multifaceted manner.

In the embodiment shown in FIG. 7, the four excitation light optical systems 24 are arranged in the four void portions 30, respectively, but the numbers of the excitation light optical system 24 and the void portions 30 are not particularly limited.

The present invention has been described above based on the embodiment. This embodiment is merely an example, and it is understood by those skilled in the art that various modifications can be made to the combinations of their respective constituent elements and processing processes, and that such modifications are also within the scope of the present invention. is there.

10, 40, 50, 60, 70 Fluorescence detection optical device, 11 Fluorescence emission point, 12 Irradiation optical system, 13 Fluorescence focusing point, 14 Receiving optical system, 16 Excitation light source, 20 First lens group, 22 Second lens Group, 24 excitation light optical system, 25 excitation light lens group, 30 void part, 42 light emitting element, 44 fluorescence fiber, 46 light receiving unit, 52 light source unit, 54 excitation light fiber, 62 relay lens system.

Claims (8)

An optical device for fluorescence detection, which irradiates excitation light to an object to be detected, and detects fluorescence generated from the object to be detected by the irradiation,
A first lens group for directly receiving the fluorescence generated from the object to be detected,
A second lens group that is arranged coaxially with the first lens group and that receives the fluorescence that has passed through the first lens group, the off-axis part being cut away to form a void portion. When,
A pumping light optical system that emits pumping light, wherein the pumping light that is emitted is arranged so as to be irradiated onto the object to be detected through the off-axis of the first lens group.
Equipped with
An optical device for fluorescence detection, characterized in that a part of the excitation light optical system is arranged in the void portion of the second lens group. The first lens group collimates fluorescence emitted from the object to be detected,
The second lens group collects the parallel light of fluorescence from the first lens group,
The optical device for fluorescence detection according to claim 1, wherein: The optical device for fluorescence detection according to claim 1, wherein the void portion is formed at a peripheral portion of the second lens group. The excitation light optical system,
An excitation light source that emits excitation light,
A lens group for excitation light, which makes excitation light from the excitation light source parallel light and makes it incident off-axis of the first lens group;
The optical device for fluorescence detection according to claim 1, further comprising: The optical device for fluorescence detection according to claim 4, wherein the excitation light source includes a light emitting element that emits excitation light. The fluorescence detection optical device according to claim 4, wherein the excitation light source includes an emission end face of an excitation light optical fiber that guides the excitation light. The excitation light source includes a light emitting element provided in the image side space of the second lens group,
5. The optical device for fluorescence detection according to claim 4, wherein the excitation light lens group includes a relay lens system arranged to form an intermediate image of a light emitting region of the light emitting element in the void portion. A plurality of the excitation light optical system,
A plurality of the void portions are formed in the second lens group,
The fluorescence detection optical device according to claim 1, wherein a part of the excitation light optical system is arranged in each of the plurality of void portions.

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