Light irradiation device and sample observation device

Abstract

The light irradiation device (2) includes: a light source (21) that outputs light (L0) having interference; a condensing element (23) that has a condensing axis (F1) and a non-condensing axis (F2) that intersects the condensing axis (F1), condenses the light (L0) on a condensing line (K) to generate a planar light (L1); and a hole mask (22) that has an opening portion (24) that limits a portion of a light beam of the light (L0) from the light source (21) toward the condensing element (23). The opening portion (24) of the hole mask (22) has an opening edge (25A) that is arranged in a manner extending in a direction along the condensing axis (F1) of the condensing element (23), and in a case where the opening edge (25A) is projected on the condensing line (K), the projection portion (P) has a linear extension.

Description

Technical Field

[0001] This invention relates to a light irradiation device and a sample observation device. Background Technology

[0002] SPIM (Selective Plane Illumination Microscopy) is a known method for observing the interior of samples with three-dimensional structures, such as cells. As a related technology, for example, there is a sample observation device described in Patent Document 1. This sample observation device of Patent Document 1 includes an illumination optical system for irradiating the sample with planar light, a scanning unit for scanning the sample with the irradiated surface of the planar light, and an observation axis tilted relative to the irradiated surface. It also includes an imaging optical system for imaging the observation light generated on the sample by the illumination of the planar light. Furthermore, it acquires multiple partial image data corresponding to portions of the light image based on the observation light formed by the imaging optical system, and generates observation image data of the sample based on these partial image data.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2018-063292 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] The planar light used in the aforementioned sample observation apparatus is formed, for example, by focusing light emitted from a light source using a focusing element such as a cylindrical lens. Preferably, when illuminating the sample with planar light, an aperture mask is placed in the optical path to limit the illumination range of the planar light, ensuring that the sample does not irradiate adjacent observation areas. However, coherent light, such as laser light, is interferometric, and therefore suffers from uneven irradiance distribution due to interference fringes caused by diffraction at the edges of the aperture mask.

[0008] The present invention was made to solve the above-mentioned problems, and its purpose is to provide a light irradiation device and a sample observation device capable of outputting planar light with a uniform irradiance distribution.

[0009] Methods for solving problems

[0010] One aspect of the light irradiation apparatus of the present invention includes: a light source that outputs interferometric light; a focusing element having a focusing axis and a non-focusing axis intersecting the focusing axis, which focuses light onto the focusing line to generate planar light; and an aperture shield having an opening that restricts a portion of a beam of light from the light source toward the focusing element, the opening of the aperture shield having an opening edge configured to extend in a direction along the focusing axis of the focusing element, the projection portion having a linear extension when the opening edge is projected onto the focusing line.

[0011] In this light illumination device, when the opening edge of the aperture shield, arranged to extend along the focusing axis of the focusing element, is projected onto the focusing beam, the projected portion has a linear extension. When the opening edge is projected onto the focusing beam, the projected portion becomes a dot-shaped aperture shield, and there is a tendency for the interference fringes of diffraction at the opening edge to reinforce each other, resulting in an uneven irradiance distribution of the planar light. In contrast, with an aperture shield having a linear extension in the projected portion, the interference fringes of diffraction at the opening edge do not reinforce each other, thus homogenizing the irradiance distribution of the planar light. Therefore, in this light illumination device, planar light with a homogenized irradiance distribution can be output.

[0012] The opening can also be asymmetrical about the converging light ray. Furthermore, the opening edge can also have a shape that bulges outwards towards the converging light ray. The opening can also be hexagonal. Based on these structures, interference fringes arising from diffraction at the opening edge are further suppressed, achieving further homogenization of the irradiance distribution of the planar light.

[0013] The opening can also be trapezoidal in shape. The opening edge can be zigzag in shape. The opening edge can also have a shape that bulges outward toward the converging light rays. In these structures, interference fringes caused by diffraction at the opening edge are further suppressed, and the irradiance distribution of the planar light is further homogenized.

[0014] Alternatively, the opening can be quadrilateral, with the opening edge intersecting the focusing axis at a predetermined angle. In such a structure, interference fringes caused by diffraction at the opening edge are further suppressed, achieving further homogenization of the irradiance distribution of the planar light.

[0015] The light source can also be a laser light source. Although lasers can achieve high irradiance, they are highly interferometric light, easily producing interference fringes caused by diffraction at the edges of the aperture shield. Therefore, by using an aperture shield with the above-described structure on the laser, it is possible to appropriately output planar light with a uniform irradiance distribution.

[0016] One aspect of the present invention is a sample observation apparatus comprising the above-described light irradiation device and a detection unit for detecting observation light generated on the sample due to irradiation by planar light from the light irradiation device.

[0017] In this sample observation apparatus, because the interference fringes diffracted at the opening edge of the aperture shield do not reinforce each other, the irradiance distribution of the planar light can be homogenized. Therefore, in this sample observation apparatus, the sample can be observed with high precision by irradiating it with planar light of homogenized irradiance distribution.

[0018] The effects of the invention

[0019] According to the present invention, it is possible to output planar light with a uniform irradiance distribution. Attached Figure Description

[0020] Figure 1 This is a schematic structural diagram illustrating one embodiment of the sample observation device.

[0021] Figure 2 This is a schematic diagram illustrating an example of the structure of a light irradiation device.

[0022] Figure 3 (a) is a diagram showing the shape of the opening of the comparative example aperture shield, and (b) is a graph showing the irradiance distribution of the planar light when the aperture shield is used.

[0023] Figure 4 (a) is a diagram showing the shape of the opening of the aperture shield in the embodiment, and (b) is a graph showing the irradiance distribution of planar light when the aperture shield is used.

[0024] Figure 5 (a) is a diagram showing the shape of the opening of the aperture shield in another embodiment, and (b) is a graph showing the irradiance distribution of planar light when the aperture shield is used.

[0025] Figure 6 (a) is a diagram showing the shape of the opening of the aperture shield in another embodiment, and (b) is a graph showing the irradiance distribution of planar light when the aperture shield is used.

[0026] Figure 7 (a) is a diagram showing the shape of the opening of the aperture shield in another embodiment, and (b) is a graph showing the irradiance distribution of planar light when the aperture shield is used.

[0027] Figure 8 (a) is a diagram showing the shape of the opening of the aperture shield in another embodiment, and (b) is a graph showing the irradiance distribution of planar light when the aperture shield is used.

[0028] Figure 9 (a) is a diagram showing the shape of the opening of the aperture shield in another embodiment, and (b) is a graph showing the irradiance distribution of planar light when the aperture shield is used.

[0029] Figure 10 (a) is a diagram showing the shape of the opening of the aperture shield in another embodiment, and (b) is a graph showing the irradiance distribution of planar light when the aperture shield is used.

[0030] Figure 11 (a) is a diagram showing the shape of the opening of the aperture shield in another embodiment, and (b) is a graph showing the irradiance distribution of planar light when the aperture shield is used. Detailed Implementation

[0031] Hereinafter, with reference to the accompanying drawings, a preferred embodiment of the light irradiation device and the sample observation device of one aspect of the present invention will be described in detail.

[0032] Figure 1 This is a schematic structural diagram illustrating one embodiment of a sample observation apparatus 1. The sample observation apparatus 1 irradiates a sample S with planar light L1, causing light (e.g., fluorescence, scattered light, etc.) generated inside the sample S due to the irradiation of the planar light L1 to form an image on an imaging surface, thereby acquiring observation image data of the interior of the sample S. Examples of such a sample observation apparatus 1 include a slide scanner that acquires and displays images of the sample S held on a glass slide, or a disk reader that acquires image data of the sample S held on a microplate and analyzes the image data. Examples of samples S that can be observed include human or animal cells, tissues, organs, animal or plant cells, and plant tissues. Furthermore, the sample S may also be contained in a solution, gel, or a substance with a refractive index different from that of the sample S.

[0033] like Figure 1 As shown, the sample observation device 1 includes a light irradiation device 2, a scanning unit 4, an imaging optical system 5, an image acquisition unit (detection unit) 6, and a computer 7. The light irradiation device 2 is a device that outputs planar light L1 to irradiate the sample S. The planar light L1 is light capable of shaping laser light or low-coherence light into a planar shape. The planar light L1 output from the light irradiation device 2 travels along the optical axis P1 and irradiates the sample S. On the sample S irradiated by the planar light L1, observation light L2 is generated at the irradiated surface R of the planar light L1. The observation light L2 is, for example, fluorescence excited by the planar light L1, scattered light from the planar light L1, or diffused reflected light from the planar light L1.

[0034] The scanning unit 4 is a mechanism for scanning the sample S on the irradiation surface R of the planar light L1. In this embodiment, the scanning unit 4 is composed of a moving stage 12 that moves the sample container 11 holding the sample S. The sample container 11 is, for example, a microplate, a glass slide, a petri dish, etc. In this embodiment, a microplate is exemplified. In the sample container 11, for example, a plurality of deep grooves 13 for arranging the sample S are arranged in a straight line (or matrix). The sample container 11 may also be fixed to the moving stage 12. The bottom surface of the deep grooves 13 serves as the input surface for the planar light L1 for the sample S arranged in the deep grooves 13. The sample container 11 is arranged relative to the moving stage 12 such that the input surface is orthogonal to the optical axis P1 of the planar light L1.

[0035] like Figure 1 As shown, the moving stage 12 scans the sample container 11 in a predetermined direction according to the control signal from the computer 7. In this embodiment, the moving stage 12 scans the sample container 11 in a direction within a plane orthogonal to the optical axis P1 of the planar light L1. Here, the direction of the optical axis P1 of the planar light L1 is referred to as the Z-axis, the scanning direction of the sample container 11 driven by the moving stage 12 is referred to as the Y-axis, and the direction orthogonal to the Y-axis within the plane orthogonal to the optical axis P1 of the planar light L1 is referred to as the X-axis. The irradiation surface R of the sample S by the planar light L1 is called a surface within the XZ plane.

[0036] Imaging optical system 5 is an optical system that images the observation light L2 generated by the planar light L1 illuminating the sample S. Imaging optical system 5 includes, for example, an objective lens and an imaging lens. The optical axis of imaging optical system 5 becomes the observation axis P2 of the observation light L2. Figure 1 In the example, the observation axis P2 of the imaging optical system 5 is tilted at a predetermined angle relative to the illumination surface R of the planar light L1 of the sample S. The tilt angle of the observation axis P2 is also consistent with the angle formed by the optical axis P1 of the planar light L1 towards the sample S and the observation axis P2.

[0037] The image acquisition unit 6 is the part that detects the observation light L2 imaged by the imaging optical system 5. The image acquisition unit 6 includes, for example, an imaging device that captures a light image based on the observation light L2. As an imaging device, examples include area image sensors such as CMOS image sensors and CCD image sensors. These area image sensors are arranged on the imaging surface of the imaging optical system 5, and capture the light image, for example, using a global shutter or a rolling shutter, and output the two-dimensional image data to the computer 7.

[0038] The computer 7 physically includes memory such as RAM and ROM, a processor (processor circuit) such as a CPU, a communication interface, a storage unit such as a hard disk, and a display unit such as a monitor. Examples of computers 7 include personal computers, cloud servers, and smart devices (smartphones, tablets, etc.). The computer 7 executes programs stored in the memory via the CPU of the computer system, functioning as a controller for controlling the operation of the light irradiation device 2 and the moving stage 12, an image generation unit for generating observation image data of the sample S, and an analysis unit for analyzing the observation image data.

[0039] Next, the light irradiation device 2 described above will be explained in more detail.

[0040] Figure 2 This is a schematic diagram illustrating an example of the structure of a light irradiation device. As shown in the figure, the light irradiation device 2 includes a light source 21 that outputs light L0, an aperture shield 22 that confines a portion of the light beam L0, and a focusing element 23 that focuses the light L0 to generate planar light L1, though details will be described later. Examples of light sources 21 include laser diodes and solid-state laser sources. The light source 21 is not limited to a laser-outputting light source; for example, it could be a light source that outputs low-coherence light, such as an SLD (Superluminescent Diode). Both laser light and low-coherence light are interferometric. The aperture shield 22A has an opening 24 that confines a portion of the light beam L0 from the light source 21 toward the focusing element 23. By confining a portion of the light beam L0 using the opening 24, the irradiation range of the planar light L1 output from the light irradiation device 2 can be limited, preventing the planar light from irradiating adjacent observation areas onto the sample S disposed in the sample container 11 of the sample observation device 1.

[0041] The focusing element 23 is composed of, for example, a cylindrical lens, an axial lens, a freeform lens, or a spatial light modulator, and is optically coupled to the light source 21. The focusing element 23 has a focusing axis F1 and a non-focusing axis F2 that intersects (or is orthogonal to) the focusing axis F1, and focuses the light L0 passing through the opening 24 onto the focusing ray K to generate a planar light L1. Figure 2 In this example, the focusing element 23 is a cylindrical lens. Figure 2 (a) represents the optical axis of light L0 in the focusing axis section (YZ section) of the focusing element 23. Figure 2 (b) represents the optical axis of light L0 in the non-focusing axis side section (XZ section) of the focusing element 23.

[0042] like Figure 2 As shown in (a), when viewed from the axial section (YZ section), the light L0 passing through the opening 24 passes through the focusing element 23, thereby focusing the light along the focusing axis F1 of the focusing element 23. On the other hand, as Figure 2 As shown in (b), when viewed from the non-focusing axis side section (XZ section), the light L0 passing through the opening 24 is not focused by the focusing element 23, but remains in the state it was in before incident on the focusing element 23. Therefore, the light L0 passes through the focusing element 23 and is focused only on one axis (Y-axis) of the focusing axis F1, becoming a planar light L1 with a certain width in the X-axis direction.

[0043] Here, as mentioned above, when an aperture shield is placed in the optical path of coherent light such as a laser, the coherent light is generally highly interferometric. Therefore, due to diffraction at the opening edge of the aperture shield, interference fringes are generated in the laser light after passing through the opening, which becomes a problem. This problem can also occur even if the light passing through the opening of the aperture shield is low-coherence light. The interference fringes caused by diffraction at the opening edge of the aperture shield overlap and reinforce each other when the light is focused by the focusing element in the direction along the focusing axis. Therefore, it is believed that the irradiance distribution of the planar light obtained by focusing the light will be non-uniform.

[0044] Figure 3 Figure (a) shows the shape of the opening of the aperture mask of the comparative example. The aperture mask 122 of this comparative example has a rectangular (quadrilateral) opening 124 including an opening edge 125A corresponding to the long side and an opening edge 125B corresponding to the short side. The aperture mask 122 is arranged in the optical path of the light L0 such that, when viewed from the optical axis direction of the light L0, the opening edge 125A extends in a direction parallel to the focusing axis F1 of the focusing element 23, and the opening edge 125B extends in a direction orthogonal to the focusing axis of the focusing element 23. The focusing ray K of the light L0 focused by the focusing element 23 is located on the line connecting the centers of the left and right opening edges 125A, 125A, when viewed from the optical axis direction of the light L0.

[0045] In the aperture shield 122 of this comparative example, as Figure 3 As shown in (a), when the opening edge 125A is projected onto the focusing ray, the projected portion P on the focusing ray K of the opening edge 125A becomes a point. Therefore, when the light L0 passing through the opening 124 is focused by the focusing element 23 in the aperture shield 122, the interference fringes of the diffraction at the opening edge 125A overlap at a single point on the focusing ray K and thus reinforce each other.

[0046] Figure 3 (b) is a graph showing the irradiance distribution of the planar light when using the aperture shield of the comparative example. In this graph, the horizontal axis represents the coordinate values ​​on the condenser ray (X-axis), and the vertical axis represents the irradiance of the planar light. As shown in the graph, for the planar light L1 using the aperture shield of the comparative example, the amplitude of the irradiance distribution near both ends in the X-axis direction is as large as 5 W / mm. 2The amplitude of the irradiance distribution decreases towards the center along the X-axis, reaching 1 W / mm² near the center. 2 Degree. Additionally, the amplitude of irradiance distribution refers to the range between the maximum and minimum values ​​in a region with roughly uniform irradiance.

[0047] on the other hand, Figure 4 Figure (a) is a diagram showing the shape of the opening of the aperture mask of the embodiment. Like the comparative example, the aperture mask 22A has a rectangular (quadrilateral) opening 24A comprising an opening edge 25A corresponding to the long side and an opening edge 25B corresponding to the short side. In the aperture mask 22A, the shape of the opening 24A is the same as that of the opening 124 in the comparative example; however, unlike the comparative example, it is a state where the rectangular opening 24A is rotated about the optical axis of the light L0 by a predetermined angle. Therefore, when viewed from the optical axis direction of the light L0, the aperture mask 22A has the opening edge 25A intersecting at a predetermined angle relative to a direction parallel to the focusing axis F1, and the opening edge 25B intersecting at a predetermined angle relative to a direction not parallel to the focusing axis.

[0048] The specified angle is, for example, between 1° and 5°. By setting the specified angle to 1° or more, the effect of reducing interference fringes can be fully utilized. Furthermore, by setting the specified angle to 5° or less, excessive expansion of the lower edge of the irradiance distribution can be suppressed, and a region with a relatively flat irradiance can be sufficiently ensured. In addition, the length of the opening 24A in the direction of the focusing axis F1 can also be considered when setting the optimal specified angle.

[0049] In this embodiment, the hole shield 22A, such as Figure 4 As shown in (a), when the opening edge 25A is projected onto the focusing ray, the projected portion P on the focusing ray K of the opening edge 25A has a linear extension. Therefore, when the light L0 passing through the opening 24A is focused by the focusing element 23 in the aperture shield 22A, it is possible to suppress the interference fringes caused by diffraction at the opening edge 25A from overlapping and reinforcing each other on the focusing ray K.

[0050] Figure 4 (b) is a graph showing the irradiance distribution of planar light when using the aperture shield of the embodiment. In this graph, compared with... Figure 3 Similar to (b), the horizontal axis represents the coordinate values ​​on the focusing ray (X-axis), and the vertical axis represents the irradiance of the planar light. As shown in the figure, in the case of the aperture mask used in the embodiment, the amplitude of the irradiance distribution near both ends of the planar light L1 in the X-axis direction is suppressed to 1 W / mm. 2 The amplitude of the irradiance distribution near the center was suppressed to approximately 0 W / mm. 2 .

[0051] As explained above, in the light irradiation device 2, when the opening edge 25A of the aperture mask 22A, which is arranged to extend in the direction along the focusing axis F1 of the focusing element 23, is projected onto the focusing beam K, the projection portion P has a linear extension. In a comparative example of the aperture mask 22 where the projection portion P is a dot, due to the mutual reinforcement of interference fringes at the opening edge 25A, the irradiance distribution of the planar light L1 tends to be uneven. In contrast, in the embodiment where the aperture mask 22A has a linear extension in the projection portion P, the interference fringes at the opening edge 25A do not reinforce each other, thus homogenizing the irradiance distribution of the planar light L1. Therefore, in this light irradiation device 2, planar light L1 with a homogenized irradiance distribution can be output.

[0052] In addition, as a technique to suppress interference fringes caused by diffraction of light at the aperture edge of the aperture shield, one method is to place a filter, called an apodization filter or soft aperture, in the optical path. Furthermore, instead of a filter, there is a method of placing an aspherical lens in the optical path to suppress diffraction components. However, in these methods, the optical elements need to be optimized according to the wavelength and beam diameter of the laser used. If a laser whose characteristics are unsuitable for the optical elements is used, there is a problem that the effect of suppressing interference fringes caused by diffraction of light at the aperture edge cannot be fully realized.

[0053] In contrast, in the light irradiation device 2, the structure of the opening edge 25A of the aperture shield 22A suppresses interference fringes caused by diffraction of light L0 at the opening edge 25A. In this method, it is necessary to optimize the optical elements according to the wavelength and beam diameter of the light L0 used to obtain the desired effect for various types of light L0. This is particularly significant when applied to a sample observation device 1 as described in the above embodiment, where light L0 with different wavelengths and beam diameters is envisioned as a planar light L1 coaxially irradiating the sample S.

[0054] Figure 5 Figure (a) is a diagram showing the shape of the opening of a hole mask according to another embodiment. In the hole mask 22B shown in this figure, instead of a structure that rotates the rectangular opening 24A about the optical axis of the light source L0 at a predetermined angle (see Figure 22B). Figure 4 (a) The shape of the opening 24B is a parallelogram (quadrilateral shape). Thus, when viewed from the optical axis direction of light L0, the opening edge 25A of the hole shield 22B is tilted at a predetermined angle relative to the direction parallel to the focusing axis F1, and the opening edge 25B is parallel to the non-focusing axis.

[0055] In such a hole mask 22B, such as Figure 5As shown in (a), when the opening edge 25A is projected onto the focusing ray, the projected portion P on the focusing ray K of the opening edge 25A has a linear extension. Therefore, with the aperture shield 22B, it is also possible to suppress the situation where interference fringes caused by diffraction at the opening edge 25A overlap and reinforce each other on the focusing ray K when the light L0 passing through the opening 24B is focused by the focusing element 23. Figure 5 As shown in (b), the irradiance distribution of the planar light L1 when using aperture mask 22B is approximately the same as that when using aperture mask 22A.

[0056] Figure 6 Figure (a) is a diagram showing the shape of the opening of a hole mask according to another embodiment. In the hole mask 22C shown in this figure, the opening 24C has an asymmetrical shape with respect to the focusing light beam K. More specifically, in Figure 6 In example (a), the opening 24C is shaped like an isosceles trapezoid (quadrilateral). Therefore, when viewed from the optical axis of light L0, the aperture shield 22C has its opening edge 25A tilted at a predetermined angle relative to the direction parallel to the focusing axis F1, and its opening edge 25B parallel to the non-focusing axis. Furthermore, in this figure, the length of the lower base of the opening 24C in the direction of the non-focusing axis F2 is longer than the length of the upper base in the direction of the non-focusing axis F2; ​​however, this length relationship can be reversed.

[0057] In such a hole mask 22C, such as Figure 6 As shown in (a), when the opening edge 25A is projected onto the focusing ray, the projected portion P on the focusing ray K of the opening edge 25A has a linear extension. Therefore, with the aperture shield 22C, it is also possible to suppress the situation where interference fringes caused by diffraction at the opening edge 25A overlap and reinforce each other on the focusing ray K when the light L0 passing through the opening 24C is focused by the focusing element 23. Figure 6 As shown in (b), the irradiance distribution of the planar light L1 when using aperture mask 22C is approximately the same as that when using aperture mask 22A.

[0058] Figure 7 Figure (a) shows the shape of the opening of a hole mask according to another embodiment. In the hole mask 22D shown in this figure, not only is the opening 24D shaped like an isosceles trapezoid, similar to hole mask 22C, but its opening edge 25A is also zigzag-shaped. In such a hole mask 22D, when the opening edge 25A is projected onto a focusing ray, the projected portion P on the focusing ray K of the opening edge 25A has a linear extension. Therefore, in the hole mask 22D, it is also possible to suppress the situation where interference fringes caused by diffraction at the opening edge 25A overlap and reinforce each other on the focusing ray K when light L0 passing through the opening 24D is focused by the focusing element 23.

[0059] like Figure 7 As shown in (b), the irradiance distribution of the planar light L1 using aperture mask 22D is approximately the same as that using aperture mask 22A. Figure 7 The result of (b) is the same as Figure 4 Compare the results of (b) with those of the other two. Figure 7 In result (b), the rising edge of the irradiance distribution near the two ends of the X-axis direction of the planar light L1 is steeper, and the amplitude of the irradiance distribution near the two ends of the X-axis direction is also slightly smaller. Additionally, in Figure 7 In example (a), the zigzag-shaped opening edge 25A has a pointed shape, but the opening edge 25A can also be a curved shape such as an arc or a sine wave.

[0060] In addition, it can also be like Figure 8 As shown in (a) with aperture mask 22E, the rectangular (quadrilateral) opening 24E is rotated about the optical axis of the light L0 at a predetermined angle, and the opening edge 25A is zigzag-shaped. When using such an aperture mask 22E, it is also like... Figure 8 As shown in (b), it is possible to obtain a radiance distribution of the planar light L1 that is approximately the same as when using the aperture mask 22D.

[0061] Figure 9 Figure (a) is a diagram showing the shape of the opening of a hole mask according to another embodiment. In the hole mask 22F shown in this figure, the opening edge 25A of the opening 24F has a shape that protrudes outward from the focusing light beam K. More specifically, in Figure 9 In example (a), the opening 24F is hexagonal in shape, with two opposite sides arranged in a direction parallel to the non-focusing axis F2. The opening 24F is not a regular hexagon; at the opening edge 25A, the corners of the hexagonal shape are positioned towards one side of the focusing ray K (here, the lower side of the paper). Therefore, this opening 24F, like the opening 24C of the aperture mask 22C, is asymmetrical about the focusing ray K. The corners of the hexagonal shape can also be positioned towards the other side of the focusing ray K (the upper side of the paper).

[0062] In such an aperture shield 22F, when the opening edge 25A is projected onto the focusing ray, the projected portion P on the focusing ray K of the opening edge 25A has a linear extension. Therefore, with the aperture shield 22F, it is also possible to suppress the situation where interference fringes caused by diffraction at the opening edge 25A overlap and reinforce each other on the focusing ray K when the light L0 passing through the opening 24F is focused by the focusing element 23. Figure 9As shown in (b), the irradiance distribution of the planar light L1 when using aperture mask 22C is approximately the same as that when using aperture mask 22A, except that the amplitude of the irradiance distribution near both ends in the X-axis direction is further suppressed.

[0063] As an example, the opening edge 25A can have a shape that protrudes outward toward the converging ray K. Figure 10 As shown in (a) of the aperture shield 22G, it adopts a shape in which the opening edge 25A of the rectangular opening 24G is slowly curved outward. In this case, as Figure 10 As shown in (b), in the irradiance distribution of the planar light L1, although a small amplitude is produced in the rising edge portion of the irradiance distribution near both ends in the X-axis direction, as a whole it becomes approximately the same result as when using the aperture mask 22A.

[0064] Furthermore, as another way, the opening edge 25A can have a shape that protrudes outward toward the converging ray K, for example, it can also be as follows: Figure 11 As shown in (a) with aperture shield 22H, it adopts a shape in which the rectangular opening 24H rotates about the optical axis of the light L0 at a predetermined angle, and the opening edge 25A is slowly curved outward. In this case, as Figure 11 As shown in (b), in the irradiance distribution of the planar light L1, although a small amplitude is produced at the rising edge of the irradiance distribution near both ends in the X-axis direction, the overall result is approximately the same as when using the aperture mask 22A.

[0065] Explanation of reference numerals in the attached figures

[0066] 1……Sample observation device; 6……Image acquisition unit (detection unit); 21……Light source; 22 (22A~22H)……Aperture mask; 23……Concentrating element; 24 (24A~24H)……Opening; 25A……Opening edge; F1……Concentrating axis; F2……Non-concentrating axis; K……Concentrating ray; L0……Light; L1……Planar light; P……Projection part; S……Sample.

Claims

1. A light irradiation device, wherein: have: A light source that outputs interferometric light; A light-concentrating element having a light-concentrating axis and a non-light-concentrating axis intersecting the light-concentrating axis, which concentrates the light onto the light-concentrating axis to generate planar light; and An aperture shield having an opening that restricts a portion of the light beam from the light source toward the focusing element. The opening of the aperture shield has an opening edge arranged to extend along the focusing axis of the focusing element, and when the opening edge is projected onto the focusing line, the projected portion has a linear extension. The opening is hexagonal in shape. The aperture shield is positioned between the light source and the focusing element. The opening has an asymmetrical shape with respect to the focusing light beam.

2. The light irradiation device as claimed in claim 1, wherein: The opening edge has a shape that protrudes outward toward the focusing light beam.

3. The light irradiation device as described in claim 1 or 2, wherein: The opening edge is zigzag-shaped.

4. The light irradiation device according to any one of claims 1 to 3, wherein: The light source is a laser light source that outputs laser light.

5. A sample observation device, wherein, have: The light irradiation device according to any one of claims 1 to 4; and The detection unit detects the observation light generated on the sample due to the irradiation of the planar light from the light irradiation device.

Images