JP2022166290A - Sample observation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sample observation device which can reduce astigmatism of observation light.

SOLUTION: A sample observation device 1 comprises: an irradiation optical system 3 which irradiates a sample S with planar light L2; a scan unit 4 which scans the sample S in one direction so as to pass through the irradiation surface R of the planar light L2; an image formation optical system 5 which has an observation axis P2 inclined with respect to the irradiation surface R and forms an image with the observation light L3 generated in the sample S by the irradiation with planar light L2; an image acquisition unit 6 which acquires image data 31 corresponding to the light image of the observation light L3 whose image is formed by the image formation optical system 5; and an image generation unit 8 which generates observation image data 32 of the sample S on the basis of the image data 31 acquired by the image acquisition unit 6. The image formation optical system 5 includes a non-axial symmetric optical element which bends the light ray L3a of one axis of the observation light L3 but does not bend the light ray L3b of the other axis orthogonal to the one axis.

SELECTED DRAWING: Figure 9

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present disclosure relates to a sample observation device.

SPIM (Selective Plane Illumination Microscopy) is known as one of techniques for observing the inside of a sample having a three-dimensional structure such as a cell. For example, the tomographic image observation apparatus described in Patent Document 1 discloses the basic principle of SPIM. Observation image data of the inside of the sample is obtained by forming an image.

Another sample observation device using planar light is, for example, the SPIM microscope described in Patent Document 2. In this conventional SPIM microscope, planar light is irradiated with a certain tilt angle with respect to the surface on which the sample is arranged, and the observation light from the sample is emitted by an observation optical system having an observation axis perpendicular to the irradiation surface of the planar light. is imaged.

JP-A-62-180241 JP 2014-202967 A

In the configuration in which the irradiation optical system and the observation optical system are each tilted with respect to the arrangement plane of the sample, as in the above-mentioned Patent Document 2, the effect of astigmatism of the observation light is conceivable. In order to reduce the influence of astigmatism, this patent document 2 proposes observing a sample with an immersion objective lens using a sample placement portion having a refractive index similar to that of water. However, with such a configuration, it becomes difficult to perform observation while scanning the sample, and there is a risk that the throughput until observation image data is obtained will decrease.

An object of the present disclosure is to provide a sample observation apparatus capable of reducing astigmatism of observation light.

A sample observation apparatus according to one aspect of the present disclosure includes an irradiation optical system that irradiates a sample with planar light, a scanning unit that scans the sample in one direction so as to pass through the irradiation surface of the planar light, and an imaging optical system that has an observation axis inclined with respect to the specimen and forms an image of the observation light generated by the specimen by the irradiation of the planar light; and an image corresponding to the optical image of the observation light formed by the imaging optical system. an image acquisition unit for acquiring data; and an image generation unit for generating observation image data of a sample based on the image data acquired by the image acquisition unit. It has non-axisymmetric optical elements that bend light while not bending light rays on the other axis.

In this sample observation apparatus, the imaging optical system has a non-axisymmetric optical element that bends one axis of observation light while not bending the other axis of observation light. As a result, even when the observation axis of the imaging optical system is inclined with respect to the irradiation surface of the planar light, the astigmatism of the observation light in the imaging optical system can be reduced, and the observation image data can be obtained. can improve image quality.

The optical element may be a wedge prism. In this case, a non-axisymmetric optical element can be preferably constructed.

The optical element may be a cylindrical lens. In this case, a non-axisymmetric optical element can be preferably constructed.

The imaging optics may include an objective lens, and the optical element may be positioned between the illumination surface and the objective lens. By arranging the optical element between the irradiation surface and the objective lens, the above-described effects are favorably achieved.

The imaging optics may include an objective lens, and the optical element may be positioned between the objective lens and the image acquisition unit. When the optical element is arranged at this position, it becomes difficult for the optical element to interfere with other components, and the imaging optical system can be easily constructed.

The imaging optics may include an objective lens and an imaging lens, and the optical element may be arranged between the imaging lens and the image acquisition section. When the optical element is arranged at this position, it becomes difficult for the optical element to interfere with other components, and the imaging optical system can be easily constructed.

The imaging optics may include an objective lens and an imaging lens, and the optical element may be positioned between the objective lens and the imaging lens. When an infinity correcting optical system is composed of an objective lens and an imaging lens, the same effect as described above can be preferably obtained by arranging an optical element between the objective lens and the imaging lens.

The inclination angle of the observation axis of the imaging optical system with respect to the irradiation surface of the planar light may be 10° to 80°. Within this range, a sufficient resolution of the observed image can be ensured.

The angle of inclination of the observation axis of the imaging optical system with respect to the irradiation surface of planar light may be 20° to 70°. Within this range, the resolution of the observed image can be more sufficiently secured. In addition, it is possible to suppress the change in the field of view with respect to the angle change amount of the observation axis, and to ensure the stability of the field of view.

The inclination angle of the observation axis of the imaging optical system with respect to the irradiation surface of planar light may be 30° to 65°. Within this range, the resolution of the observed image and the stability of the field of view can be secured more favorably.

The sample observation device may further include an analysis section that analyzes observation image data and generates an analysis result. Since the analysis unit analyzes the observation image data generated by the image generation unit, the analysis throughput can be improved.

According to the present disclosure, astigmatism of observation light can be reduced.

1 is a schematic configuration diagram showing an embodiment of a sample observation device; FIG. FIG. 2 is an enlarged view of a main part showing the vicinity of a sample; FIG. 4 is a diagram showing an example of generation of observation image data by an image generation unit; It is a figure which shows the mode of image acquisition by an image acquisition part. FIG. 10 is a diagram showing an example of calculation of a field of view in the sample observation device; FIG. 4 is a diagram showing the relationship between the tilt angle of the observation axis and the resolution; FIG. 5 is a diagram showing the relationship between the tilt angle of the observation axis and the stability of the field of view; FIG. 4 is a diagram showing the relationship between the tilt angle of the observation axis and the transmittance of observation light from the sample; It is a figure which shows an example of a structure of an imaging optical system. FIG. 10 is a diagram showing how a ray of observation light passes through a wedge prism; FIG. 4 is a comparison diagram of astigmatism of observation light with and without a wedge prism; It is a figure which shows another example of a structure of an imaging optical system. FIG. 10 is a diagram showing still another example of the configuration of the imaging optical system; FIG. 10 is a diagram showing still another example of the configuration of the imaging optical system; FIG. 10 is a diagram showing still another example of the configuration of the imaging optical system; FIG. 5 is a diagram showing test results for confirming the effect of reducing astigmatism and chromatic aberration of a wedge prism; FIG. 5 is a diagram showing test results for confirming the effect of reducing astigmatism and chromatic aberration of a wedge prism; FIG. 5 is a diagram showing test results for confirming the effect of reducing astigmatism and chromatic aberration of a wedge prism;

Hereinafter, preferred embodiments of a sample observation device according to one aspect of the present disclosure will be described in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing one embodiment of a sample observation device. The sample observation apparatus 1 irradiates the sample S with planar light L2, and forms an image of the observation light (for example, fluorescence or scattered light) generated inside the sample S on an imaging plane to obtain an observation image of the inside of the sample S. A device that acquires data. A sample observation apparatus 1 of this type includes a slide scanner that acquires and displays an image of a sample S held on a slide glass, or a plate scanner that acquires image data of a sample S held on a microplate and analyzes the image data. There are readers, etc. As shown in FIG. 1, the sample observation apparatus 1 includes a light source 2, an irradiation optical system 3, a scanning section 4, an imaging optical system 5, an image acquisition section 6, and a computer 7. there is

Examples of the sample S to be observed include human or animal cells, tissues, organs, animal or plant itself, and plant cells and tissues. Moreover, the sample S may be contained in a solution, a gel, or a substance having a different refractive index from that of the sample S.

The light source 2 is a light source that outputs light L1 with which the sample S is irradiated. Examples of the light source 2 include laser light sources such as laser diodes and solid-state laser light sources. Also, the light source 2 may be a light-emitting diode, a super-luminescent diode, or a lamp-based light source. Light L<b>1 output from the light source 2 is guided to the irradiation optical system 3 .

The irradiation optical system 3 is an optical system that shapes the light L1 output from the light source 2 into planar light L2 and irradiates the sample S with the shaped planar light L2 along the optical axis P1. In the following description, the optical axis P1 of the irradiation optical system 3 may be referred to as the optical axis of the planar light L2. The irradiation optical system 3 includes a light shaping element such as a cylindrical lens, an axicon lens, or a spatial light modulator, and is optically coupled to the light source 2 . The irradiation optical system 3 may be configured including an objective lens. The sample S is irradiated with the planar light L2 formed by the irradiation optical system 3 . In the sample S irradiated with the planar light L2, the observation light L3 is generated on the irradiation surface R of the planar light L2. The observation light L3 is, for example, fluorescence excited by the planar light L2, scattered light of the planar light L2, or diffuse reflected light of the planar light L2.

When observation is performed in the thickness direction of the sample S, the planar light L2 is preferably thin planar light with a thickness of 2 mm or less in consideration of resolution. Further, when the thickness of the sample S is very small, that is, when observing a sample S having a thickness equal to or less than the Z-direction resolution, which will be described later, the thickness of the planar light L2 does not affect the resolution. Therefore, planar light L2 having a thickness exceeding 2 mm may be used.

The scanning unit 4 is a mechanism that scans the sample S with respect to the irradiation surface R of the planar light L2. In this embodiment, the scanning unit 4 is configured by a moving stage 12 that moves a sample container 11 holding the sample S. As shown in FIG. The sample container 11 is, for example, a microplate, a slide glass, a petri dish, etc., and has transparency to the planar light L2 and the observation light L3. In this embodiment, a microplate is exemplified. As shown in FIG. 2, the sample container 11 includes a plate-like main body portion 14 in which a plurality of wells 13 in which the sample S is placed are arranged in a straight line (or in a matrix), and one surface of the main body portion 14 is provided with wells 13 . and a plate-shaped transparent member 15 provided so as to close one end side of the plate 13 .

When placing the sample S in the well 13, the well 13 may be filled with a medium such as water. The transparent member 15 has an input surface 15 a for planar light L 2 to the sample S placed in the well 13 . The material of the transparent member 15 is not particularly limited as long as it is a member having transparency to the planar light L2, and is, for example, glass, quartz, or synthetic resin. The sample container 11 is arranged with respect to the moving stage 12 so that the input surface 15a is orthogonal to the optical axis P1 of the planar light L2. The other end side of the well 13 is open to the outside. The sample container 11 may be fixed with respect to the moving stage 12 .

The moving stage 12 scans the sample container 11 in a preset direction according to control signals from the computer 7, as shown in FIG. In this embodiment, the moving stage 12 scans the sample container 11 in one direction within a plane perpendicular to the optical axis P1 of the planar light L2. In the following description, the direction of the optical axis P1 of the planar light L2 is the Z axis, the scanning direction of the sample container 11 by the moving stage 12 is the Y axis, and the plane perpendicular to the optical axis P1 of the planar light L2 is perpendicular to the Y axis. The direction to do is called the X-axis. The irradiation surface R of the planar light L2 with respect to the sample S is a surface within the XZ plane.

The imaging optical system 5 is an optical system that forms an image of the observation light L3 generated at the sample S by the irradiation of the planar light L2. The imaging optical system 5 includes, for example, an objective lens 16, as shown in FIG. The optical axis of the imaging optical system 5 is the observation axis P2 of the observation light L3. The observation axis P2 of the imaging optical system 5 is inclined with respect to the irradiation surface R of the planar light L2 on the sample S at an inclination angle θ. The tilt angle θ also coincides with the angle formed by the optical axis P1 of the planar light L2 directed toward the sample S and the observation axis P2. The inclination angle θ is 10° to 80°. From the viewpoint of improving the resolution of the observed image, the tilt angle θ is preferably 20° to 70°. Further, from the viewpoint of improving the resolution of the observed image and stabilizing the field of view, the tilt angle θ is more preferably 30° to 65°.

As shown in FIG. 1, the image acquisition unit 6 is a device that acquires a plurality of image data corresponding to the optical image formed by the imaging optical system 5 and formed by the observation light L3. The image acquisition unit 6 includes, for example, an imaging device that captures an optical image using the observation light L3. Examples of imaging devices include area image sensors such as CMOS image sensors and CCD image sensors. These area image sensors are arranged on the imaging plane of the imaging optical system 5 , take optical images by, for example, a global shutter or a rolling shutter, and output two-dimensional image data to the computer 7 .

The image acquisition unit 6 may acquire a plurality of partial image data corresponding to a part of the optical image by the observation light L3. In this case, for example, a subarray may be set on the imaging surface of the area image sensor, and partial image data may be obtained by reading out only the pixel columns included in the subarray. Further, partial image data may be acquired by extracting a part of the two-dimensional image by image processing after all the pixel rows of the area image sensor are used as the readout area. A line sensor may be used in place of the area image sensor, and partial image data may be obtained by limiting the imaging surface itself to one pixel row. A slit that transmits only part of the observation light L3 may be arranged in front of the area image sensor, and the image data of the pixel row corresponding to the slit may be acquired as the partial image data. When using a slit, a point sensor such as a photomultiplier tube may be used instead of the area image sensor.

The computer 7 physically includes a memory such as a RAM and a ROM, a processor (arithmetic circuit) such as a CPU, a communication interface, a storage unit such as a hard disk, and a display unit such as a display. Such computers 7 include, for example, personal computers, cloud servers, smart devices (smartphones, tablet terminals, etc.). The computer 7 includes a controller that controls the operation of the light source 2 and the moving stage 12, an image generator 8 that generates observation image data of the sample S, and an observation It functions as an analysis unit 10 that analyzes image data (see FIG. 1).

The computer 7 as a controller receives a user's operation to start measurement, and drives the light source 2, the moving stage 12, and the image acquisition unit 6 in synchronization. In this case, the computer 7 may control the light source 2 so that the light source 2 continuously outputs the light L1 while the sample S is being moved by the moving stage 12. ON/OFF of the output of the light L1 may be controlled. If the irradiation optical system 3 includes an optical shutter (not shown), the computer 7 may turn on/off the irradiation of the sample S with the planar light L2 by controlling the optical shutter.

Further, the computer 7 as the image generating section 8 generates observed image data of the sample S based on the plurality of image data generated by the image acquiring section 6 . The image generation unit 8 generates observation image data of the sample S on a plane (XY plane) orthogonal to the optical axis P1 of the planar light L2, for example, based on the plurality of partial image data output from the image acquisition unit 6. . The image generator 8 stores the generated observation image data and displays it on a monitor or the like in accordance with a predetermined operation by the user.

In this embodiment, as shown in FIGS. 1 and 2, the irradiation surface R of the planar light L2 with respect to the sample S is a surface within the XZ plane, and the irradiation surface R with respect to the sample S extends in the Y-axis direction. Scanned. Therefore, as shown in FIG. 3A, the image generator 8 accumulates three-dimensional information of the sample S by acquiring a plurality of image data 31, which are XZ cross-sectional images, in the Y-axis direction. The image generator 8 reconstructs data using a plurality of image data 31, and generates observed image data 32 with a suppressed background, as shown in FIG. 3B, for example. Here, the observed image data 32 is data representing an XY cross-sectional image having an arbitrary thickness at an arbitrary position on the sample S in the Z-axis direction.

The computer 7 as the analysis unit 10 executes analysis based on the observation image data 32 generated by the image generation unit 8 and generates analysis results. The analysis unit 10 stores the generated analysis results and displays them on a monitor or the like in accordance with a predetermined operation by the user. Note that the observation image data 32 generated by the image generation unit 8 may not be displayed on the monitor or the like, and only the analysis result generated by the analysis unit 10 may be displayed on the monitor or the like. By analyzing the observation image data generated by the image generation unit 8 by the analysis unit 10, the analysis throughput can be improved.

Next, the sample observation device 1 described above will be described in more detail.

In the sample observation apparatus 1, as shown in FIG. 4A, the image acquisition unit 6 acquires an image while scanning the sample S with respect to the irradiation surface R of the planar light L2. Further, in the sample observation device 1, the observation axis P2 of the imaging optical system 5 is inclined with respect to the irradiation surface R of the planar light L2. Therefore, the image acquisition unit 6 can sequentially acquire the image data 31 of the tomographic plane in the optical axis P1 direction (Z-axis direction) of the planar light L2. Observation image data 32 of the sample S can be generated based on.

As shown in FIG. 4B, the sample observing apparatus 1 can sequentially acquire images while scanning the sample S. As shown in FIG. In the operation of the conventional sample observation apparatus, time loss occurs due to the influence of inertia each time the moving stage is driven and stopped. On the other hand, in the sample observation apparatus 1, the number of times the moving stage 12 is driven and stopped can be reduced, and the scanning operation of the sample S and image acquisition can be performed simultaneously. Therefore, it is possible to improve the throughput until the observation image data 32 is obtained.

Further, in the sample observation apparatus 1, as shown in FIG. 2, the sample S is held by the sample container 11 having the input surface 15a of the planar light L2, and the optical axis P1 of the planar light L2 by the irradiation optical system 3 is It is arranged so as to be perpendicular to the input surface 15 a of the sample container 11 . Further, in the sample observation apparatus 1, the scanning unit 4 scans the sample S in a direction (Y-axis direction) perpendicular to the optical axis P1 (Z-axis direction) of the planar light L2 from the irradiation optical system 3. FIG. This eliminates the need for image processing such as position correction of the image data 31 acquired by the image acquisition unit 6, and facilitates the process of generating the observed image data 32. FIG.

Further, in the sample observation device 1, the inclination angle θ of the observation axis P2 of the imaging optical system 5 with respect to the irradiation surface R of the planar light L2 on the sample S is 10° to 80°, preferably 20° to 70°, or more. It is preferably 30° to 65°. This point will be considered below. FIG. 5 is a diagram showing a calculation example of the field of view in the sample observation device. In the example shown in the figure, the imaging optical system is positioned in a medium A having a refractive index of n1, and the irradiation surface of planar light is positioned in a medium B having a refractive index of n2. V is the visual field in the imaging optical system, V' is the irradiation surface, θ is the tilt angle of the observation axis with respect to the irradiation surface, θ' is the refraction angle at the interface between the media A and B, and the medium A at the tilt angle θ of the visual field V When the distance at the interface between and the medium B is L, the following equations (1) to (3) hold.
(Number 1)
L=V/cos θ (1)
(Number 2)
sin θ′=(n1/n2) sin θ (2)
(Number 3)
V'=L/tan θ' (3)

FIG. 6 is a diagram showing the relationship between the tilt angle of the viewing axis and the resolution. In the figure, the horizontal axis is the tilt angle .theta. of the observation axis, and the vertical axis is the relative value V'/V of the field of view. The value of V'/V when the refractive index n1 of medium A is 1 (air) and the refractive index n2 of medium B is changed from 1.0 to 2.0 in increments of 0.1 is the tilt angle θ is plotted against The smaller the value of V'/V, the higher the resolution in the depth direction of the sample (hereinafter referred to as "Z-direction resolution"), and the larger the value, the lower the Z-direction resolution.

From the results shown in FIG. 6, it can be seen that the value of V'/V is inversely proportional to the tilt angle θ when the refractive index n1 of medium A and the refractive index n2 of medium B are equal. Further, when the refractive index n1 of the medium A is different from the refractive index n2 of the medium B, it can be seen that the value of V'/V draws a parabola with respect to the tilt angle θ. From this result, it can be seen that the Z-direction resolution can be controlled by the refractive index of the space in which the sample is arranged, the refractive index of the space in which the imaging optical system is arranged, and the tilt angle θ of the observation axis. It can be seen that better Z-direction resolution can be obtained in the range of the tilt angle θ of 10° to 80° than in the range of the tilt angle θ of less than 10° and more than 80°.

Also, from the results shown in FIG. 6, it can be seen that the tilt angle θ at which the Z-direction resolution is maximized tends to decrease as the difference between the refractive indices n1 and n2 increases. When the refractive index n2 is in the range of 1.1 to 2.0, the tilt angle θ that maximizes the resolution in the Z direction is in the range of about 47° to about 57°. For example, when the refractive index n2 is 1.33 (water), the tilt angle θ that maximizes the Z-direction resolution is estimated to be approximately 52°. Further, for example, when the refractive index n2 is 1.53 (glass), the tilt angle θ that maximizes the Z-direction resolution is estimated to be about 48°.

FIG. 7 is a diagram showing the relationship between the tilt angle of the observation axis and the stability of the field of view. In the figure, the horizontal axis is the tilt angle θ of the observation axis, and the vertical axis is the stability of the field of view. The stability is represented by the ratio of the difference value between V'/V at the inclination angle θ+1 and V'/V at the inclination angle θ−1 with respect to V'/V at the inclination angle θ, and is expressed by the following formula (4). calculated based on The closer the stability is to 0%, the smaller the change in the visual field with respect to the change in the tilt angle, and the more stable the visual field can be evaluated. In FIG. 7, as in FIG. 6, the refractive index n1 of medium A is set to 1 (air), and the refractive index n2 of medium B is changed from 1.0 to 2.0 in steps of 0.1. degrees are plotted.
(Number 4)
Stability (%) = ((V'/V) _θ+1 - (V'/V) _θ-1 )/(V'/V) _θ (4)

From the results shown in FIG. 7, it can be seen that the stability exceeds ±20% when the tilt angle θ is less than 10° and more than 80°, making it difficult to control the field of view. On the other hand, when the tilt angle .theta. is in the range of 10.degree. Furthermore, when the tilt angle .theta. is in the range of 20.degree.

FIG. 8 is a diagram showing the relationship between the tilt angle of the observation axis and the transmittance of observation light from the sample. In the figure, the horizontal axis is the tilt angle θ of the observation axis, the left vertical axis is the relative value of the field of view, and the right vertical axis is the transmittance. In FIG. 8, taking into account the holding state of the sample in the sample container, the refractive index n1 of medium A is 1 (air), the refractive index n2 of medium B is 1.53 (glass), and the refractive index n3 of medium C is 1. .33 (water), and the transmittance value is the product of the transmittance of the interface between the mediums B and C and the interface between the mediums A and B. FIG. 8 plots the angular dependence of the P-wave transmittance, the S-wave transmittance, and their average values. In FIG. 8, the relative values of the field of view in the medium C are also plotted.

From the results shown in FIG. 8, it can be seen that the transmittance of the observation light from the sample to the imaging optical system can be varied by changing the tilt angle θ of the observation axis. It can be seen that a transmittance of at least 50% or more is obtained when the tilt angle θ is 80° or less. Further, it can be seen that a transmittance of at least 60% or more is obtained when the tilt angle θ is 70° or less, and a transmittance of at least 75% or more is obtained when the tilt angle θ is 65° or less.

From the above results, when Z-direction resolution of the sample is required, for example, the value of V'/V, which is the relative value of the field of view, is 3 or less, the stability is less than 5%, and the transmittance of the observation light is It is preferable to select the tilt angle θ from the range of 30° to 65° so that (average value of P wave and S wave) is 75% or more. Further, when the Z-direction resolution of the sample is not required, the tilt angle θ may be appropriately selected from the range of 10° to 80°. Alternatively, it is preferable to select from the range of 65° to 80°.

As described above, when the observation axis P2 of the imaging optical system 5 is tilted with respect to the irradiation surface R of the planar light L2 on the sample S, the influence of the astigmatism of the observation light L3 in the imaging optical system 5 is considered. There is a need to. If the effect of astigmatism of the observation light L3 becomes large, it is conceivable that the imaging performance of the observation light L3 on the imaging plane of the imaging optical system 5 deteriorates and the image quality of the observation image deteriorates.

On the other hand, the imaging optical system 5 of the sample observation apparatus 1 is, in more detail, composed of an objective lens 16, an imaging lens 17, and a wedge prism 18, as shown in FIG. . The objective lens 16 and the imaging lens 17 constitute an infinity correction optical system. The observation light L3 from the sample S becomes parallel light between the objective lens 16 and the imaging lens 17, and forms an image on the imaging plane (imaging plane of the image acquisition unit 6) F by the imaging lens 17. FIG.

The wedge prism 18 is arranged between the irradiation surface R of the planar light L2 and the objective lens 16 in this embodiment. In the wedge prism 18, one principal surface 18a and the other principal surface 18b are parallel in one direction, but the other principal surface 18b is constant with respect to the one principal surface 18a in the other direction orthogonal to the one direction. is a prism tilted at an angle of . That is, the wedge prism 18 is a prism whose thickness uniformly changes in one direction and whose thickness does not change in the other direction orthogonal to the one direction. For this reason, as shown in FIG. 10A, the wedge prism 18 bends the ray L3a of one axis of the observation light L3 by a predetermined deflection angle depending on the incident position, while as shown in FIG. It functions as a non-axisymmetric optical element that does not bend the ray L3b of the other axis of the observation light L3 perpendicular to the one axis. When the wedge prism 18 is arranged between the irradiation surface R of the planar light L2 and the objective lens 16 as shown in FIG. may be arranged as In this case, optical adjustment becomes easier.

FIG. 11 is a comparison diagram of astigmatism of observation light with and without a wedge prism. In the figure, the horizontal axis is the focus position, and the vertical axis is the sample depth. Assuming that the angle of inclination θ of the observation axis P2 is 45°, FIG. 11 shows sample depths of 0 μm ( The focus positions of the tangential and sagital image planes from the interface) to 300 μm are plotted, respectively.

Here, the tangential image surface is the image surface due to the axial ray L3b that is not bent by the wedge prism 18, and the sagital image surface is the image surface due to the axial ray L3a that is bent by the wedge prism. At each sample depth, the difference between the focus position of the tangential image plane and the focus position of the sagital image plane represents the degree of astigmatism of the observation light L3. From the results of FIG. 11, in all the sample depth ranges from 0 μm (interface) to 300 μm, when the wedge prism 18 is arranged in the imaging optical system 5, the wedge prism 18 is placed in the imaging optical system. 5, the difference between the focus position on the tangential image plane and the focus position on the sagital image plane is smaller. Therefore, it can be confirmed that the configuration in which the wedge prism 18 is arranged in the imaging optical system 5 contributes to the reduction of the astigmatism of the observation light L3.

In the form shown in FIG. 9, the wedge prism 18 is arranged between the irradiation surface R of the planar light L2 and the objective lens 16, but the arrangement of the wedge prism 18 is not limited to this form. . The wedge prism 18 may be arranged between the imaging lens 17 and the image acquisition section 6, as shown in FIG. 12, for example. When the objective lens 16 and the imaging lens 17 constitute an infinity correction optical system, the wedge prism 18 is arranged between the objective lens 16 and the imaging lens 17 to correct the astigmatism of the observation light L3 in the same manner as described above. The function and effect of reducing aberration are favorably exhibited. Also, the wedge prism 18 may be arranged between the objective lens 16 and the imaging lens 17 as shown in FIG. 13, for example. When the wedge prism 18 is arranged at this position, the wedge prism 18 is less likely to interfere with other components such as the scanning unit 4 , and the imaging optical system 5 can be configured easily.

Further, as shown in FIG. 14, a plurality of wedge prisms 18 may be arranged in the imaging optical system 5. FIG. A combination of two wedge prisms 18 is called a doublet prism, and a combination of three wedge prisms is called a triplet prism. In the example of FIG. 14 , two wedge prisms 18 are arranged between the irradiation surface R of the planar light L2 and the objective lens 16 . By arranging a plurality of wedge prisms 18, it is possible to reduce not only the astigmatism of the observation light L3 but also the chromatic aberration of the observation light L3.

The plurality of wedge prisms 18 may be arranged with the main surfaces 18a and 18b in contact with each other or stuck together, or may be arranged apart from each other. When the wedge prisms 18 are arranged separately, the arrangement positions of the wedge prisms 18 are between the irradiation surface R of the planar light L2 and the objective lens 16, between the objective lens 16 and the imaging lens 17, and It may be anywhere between the imaging lens 17 and the image acquisition unit 6 . For example, as shown in FIG. 15, one wedge prism 18 is arranged between the irradiation surface R of the planar light L2 and the objective lens 16, and the other wedge prism 18 is arranged between the imaging lens 17 and the image acquisition section 6. may be placed in between.

16 to 18 are diagrams showing test results for confirming the effect of the wedge prism 18 in reducing astigmatism and chromatic aberration. These confirmatory test results are diagrams showing the spot shape of the observation light L3 in increments of 50 μm when the tilt angle θ of the observation axis P2 is 55° and the sample depth ranges from 0 μm (interface) to 300 μm. The observation light L3 has four wavelengths of 458 nm, 530 nm, 629 nm, and 680 nm, and the respective spot shapes are superimposed. Larger distortion (spreading) of the spot shape in the lateral direction indicates greater astigmatism, and greater variation in the vertical direction of the spot shape indicates greater chromatic aberration (magnification chromatic aberration). The circle in the figure is the diameter of the Airy disk.

FIG. 16 shows the results of a comparative example in which the wedge prism 18 is not arranged in the imaging optical system 5. FIG. FIG. 17 shows the result of an example in which one wedge prism 18 is arranged in the imaging optical system 5. In FIG. FIG. 18 shows the result of an example in which two wedge prisms 18 are arranged in the imaging optical system 5. In FIG. From these results, when one wedge prism 18 is arranged in the imaging optical system 5, the astigmatism of the observation light L3 is reduced, and two wedge prisms 18 are arranged in the imaging optical system 5. In this case, it can be seen that both the astigmatism and chromatic aberration of the observation light L3 are reduced. From these results, it can be confirmed that the arrangement of the wedge prism 18 can reduce the astigmatism of the observation light L3 while improving the Z-direction resolution of the observation image by tilting the observation axis P2. Moreover, it can be confirmed that the chromatic aberration of the observation light L3 can also be reduced by arranging a plurality of wedge prisms 18 .

The present disclosure is not limited to the above embodiments. For example, in the above-described embodiment, the imaging optical system 5 including the objective lens 16 and the imaging lens 17 was illustrated. In this case, the wedge prism 18 may be arranged either between the irradiation surface R of the planar light L2 and the objective lens 16 or between the imaging lens 17 and the image acquisition section 6 . Further, for example, in the above-described embodiments, the wedge prism 18 was exemplified as an optical element for correcting astigmatism. etc. can also be used.

DESCRIPTION OF SYMBOLS 1... Specimen observation apparatus, 3... Irradiation optical system, 4... Scanning part, 5... Imaging optical system, 6... Image acquisition part, 8... Image generation part, 10... Analysis part, 16... Objective lens, 17... Imaging Lens 18 Wedge prism (optical element) 31 Image data 32 Observation image data L2 Planar light L3 Observation light L3a, L3b Ray P2 Observation axis R Irradiation surface S ... sample, θ ... tilt angle.

Claims (11)

an irradiation optical system for irradiating a sample with planar light;
a scanning unit that scans the sample in one direction within a plane perpendicular to the optical axis of the planar light so as to pass through the irradiation surface of the planar light;
an imaging optical system that has an observation axis that is inclined with respect to the irradiation surface and that forms an image of observation light generated in the sample by irradiation with the planar light;
an image acquisition unit that acquires image data corresponding to the optical image of the observation light formed by the imaging optical system;
an image generation unit that generates observed image data of the sample based on the image data acquired by the image acquisition unit;
The imaging optical system has a non-axisymmetric optical element that bends one axis of the observation light but does not bend the other axis orthogonal to the one axis. 2. A sample observing apparatus according to claim 1, wherein said optical element is a wedge prism. 2. A sample observing apparatus according to claim 1, wherein said optical element is a cylindrical lens. The imaging optical system includes an objective lens,
A sample observation apparatus according to any one of claims 1 to 3, wherein said optical element is arranged between said irradiation surface and said objective lens. The imaging optical system includes an objective lens,
The sample observation apparatus according to any one of claims 1 to 3, wherein the optical element is arranged between the objective lens and the image acquisition section. The imaging optical system includes an objective lens and an imaging lens,
The sample observing apparatus according to any one of claims 1 to 3, wherein the optical element is arranged between the imaging lens and the image acquisition section. The imaging optical system includes an objective lens and an imaging lens,
A specimen observing apparatus according to any one of claims 1 to 3, wherein said optical element is arranged between said objective lens and said imaging lens. 8. The sample observation apparatus according to claim 1, wherein the angle of inclination of said observation axis of said imaging optical system with respect to said surface irradiated with said planar light is 10° to 80°. 9. A sample observation apparatus according to claim 1, wherein the angle of inclination of said observation axis of said imaging optical system with respect to said surface irradiated with said planar light is 20° to 70°. The sample observation apparatus according to any one of claims 1 to 9, wherein the angle of inclination of the observation axis of the imaging optical system with respect to the irradiation surface of the planar light is 30° to 65°. The sample observation apparatus according to any one of claims 1 to 10, further comprising an analysis section that analyzes the observation image data and generates an analysis result.

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