Optical system, optical imaging device, and light irradiation device

Abstract

To provide an optical system capable of shifting the relative position between input light and output light along a direction intersecting the optical axis direction with a simple configuration, and an optical imaging device and an optical irradiation device equipped with such an optical system. [Solution] The optical system 4 is an optical system having a parallel light path portion P1 in which light L travels as parallel light, and comprises a prism section 50 having a first prism 51 including a first surface 51a and a second surface 51b inclined relative to the first surface 51a, wherein light L traveling as parallel light in the parallel light path portion P1 is incident on the prism section 50, and the prism section 50 refracts the light L at at least one of the first surface 51a and the second surface 51b, and comprises an imaging lens 43 that focuses the light L from the prism section 50, and the first prism 51 is rotatable around a central axis that intersects with direction D4, which is the optical axis direction of the parallel light path portion P1.

Description

[Technical Field]

[0001] The present invention relates to an optical system, an optical imaging device, and a light irradiation device. [Background technology]

[0002] Patent Document 1 describes an image acquisition device that includes a stage on which a sample is placed, a light emitting means that irradiates instantaneous light, an optical system that includes an objective lens arranged to face the sample on the stage and an imaging lens arranged after the objective lens, an image sensor that captures the optical image of the sample guided by the optical system, and a drive unit that moves the field of view position of the objective lens relative to the sample at a predetermined speed. In the optical system of the image acquisition device described in Patent Document 1, light from the sample is made parallel to the optical axis by the objective lens, and then converged by the imaging lens to form an image on the imaging surface of the image sensor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-87719 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, the optical system as described above is thought to be applicable to various uses, for example, by making it possible to shift (move) output light relative to the optical axis along a direction intersecting the optical axis, or by making it possible to output light shifted onto the optical axis when light shifted relative to the optical axis along a direction intersecting the optical axis is input. Furthermore, it is preferable that such shifting can be realized with a simple configuration.

[0005] The present invention aims to provide an optical system that can shift the relative position between input light and output light along a direction intersecting the optical axis direction with a simple configuration, and an optical imaging device and an optical irradiation device that include such an optical system. [Means for solving the problem]

[0006] The optical system of the present invention is [1] "an optical system having a parallel optical path portion in which light travels as parallel light, comprising a first prism including a first surface and a second surface inclined with respect to the first surface, wherein the light incident from the first surface passes through the first prism and exits from the second surface, a prism section having the first prism, wherein the light traveling as parallel light in the parallel optical path portion is incident on the prism section, and the prism section refracts the light at at least one of the first surface and the second surface, and a first lens that collects the light from the prism section, wherein the first prism is rotatable around a central axis that intersects with the optical axis direction of the parallel optical path portion."

[0007] This optical system includes a prism section having a first prism including a first surface and a second surface inclined relative to the first surface. Light traveling as parallel light in a parallel optical path portion enters the prism section, and the prism section refracts the light at at least one of the first surface and the second surface. The first prism is rotatable about a central axis intersecting the optical axis direction. With this configuration, by changing the rotation angle around the central axis of the first prism, it is possible, for example, to shift (move) light output from the optical system relative to the optical axis along a direction intersecting the optical axis direction, or, when light shifted relative to the optical axis along a direction intersecting the optical axis direction is input to the optical system, to output the light shifted onto the optical axis. Therefore, this optical system allows the relative positions of input light and output light along a direction intersecting the optical axis to be shifted with a simple configuration.

[0008] The optical system of the present invention may be [2] "the optical system according to [1], wherein the prism portion further comprises a second prism including a third surface and a fourth surface inclined with respect to the third surface, wherein the light incident from the third surface passes through the second prism and exits from the fourth surface, and the second prism refracts the light at at least one of the third surface and the fourth surface." In this case, for example, dispersion caused by refraction in the first prism can be reduced by refraction in the second prism, or the second prism can also shift light along a direction intersecting with the optical axis direction.

[0009] The optical system of the present invention may be [3] "the optical system according to [2], wherein, when the rotation angle of the first prism about the central axis is a certain angle, one of the first and second surfaces is located on the second prism side, the other of the first and second surfaces is located on the opposite side from the second prism, one of the third and fourth surfaces is located on the first prism side, the other of the third and fourth surfaces is located on the opposite side from the first prism, the one of the first and second surfaces is parallel to the one of the third and fourth surfaces, and the other of the first and second surfaces is parallel to the other of the third and fourth surfaces." In this case, the above-mentioned effects of reducing dispersion caused by refraction in the first prism by refraction in the second prism and shifting light in a direction intersecting the optical axis direction by the second prism are preferably achieved.

[0010] The optical system of the present invention may be [4] "the optical system according to [3], wherein the first prism and the second prism are arranged such that, when the rotation angle of the first prism about the central axis is the certain angle, the difference between the angle of incidence and the angle of emergence of the light at the first prism is minimized, and the difference between the angle of incidence and the angle of emergence of the light at the second prism is minimized." In this case, it is possible to minimize image distortion caused by transmission through the first prism and the second prism.

[0011] The optical system of the present invention may be [5] "the optical system according to any one of [1] to [4], further comprising a second lens which is an objective lens that outputs the light as the parallel light to the parallel light path portion, and the first lens is an imaging lens that forms an image of the light from the prism portion." In this case, in the imaging optical system, it is possible to shift the relative position between the input light and the output light (imaging position) along a direction intersecting the optical axis direction with a simple configuration.

[0012] The optical system of the present invention may be [6] "the optical system according to [5], wherein at least one of the objective lens and the imaging lens is movable along a direction intersecting the optical axis direction of the parallel optical path portion so that the light from the prism portion passes through the center of the imaging lens." In this case, for example, even when the light output from the optical system is shifted relative to the optical axis along a direction intersecting the optical axis direction, the light from the prism portion passes through the center of the imaging lens, thereby improving imaging performance.

[0013] The optical imaging device of the present invention may be [7] "an optical imaging device including the optical system according to any one of [1] to [6], an imaging unit that images light from the optical system, and a control unit that controls a rotation angle of the first prism about the central axis." In this optical imaging device, by changing the rotation angle of the first prism about the central axis, for example, it is possible to shift the imaging position in the imaging unit relative to the optical axis along a direction intersecting the optical axis direction, or when light shifted relative to the optical axis along a direction intersecting the optical axis direction is input to the optical system, it is possible to shift the light onto the optical axis and then form an image on the imaging unit.

[0014] The optical system of the present invention may be [8] "the optical system according to any one of [1] to [4], wherein the first lens is an objective lens that focuses the light from the prism portion." In this case, in the focusing optical system, it is possible to shift the relative position between the input light and the output light (focusing position) along a direction intersecting the optical axis direction with a simple configuration.

[0015] The light irradiation device of the present invention may be [9] "a light irradiation device comprising: the optical system according to [8]; a light source that outputs the light traveling as the parallel light toward the optical system; and a control unit that controls the rotation angle of the first prism about the central axis." In this light irradiation device, by changing the rotation angle of the first prism about the central axis, it is possible to shift, for example, the position at which light is focused by the objective lens relative to the optical axis along a direction intersecting the optical axis direction. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide an optical system that can shift the relative position between input light and output light along a direction intersecting the optical axis direction with a simple configuration, and an optical imaging device and an optical irradiation device that include such an optical system. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a diagram showing an optical imaging device to which an optical system according to an embodiment is applied; [Figure 2] FIG. 1 is a diagram illustrating an optical system according to an embodiment. [Figure 3] FIG. 2 is a diagram for explaining a parallel light path portion of an optical system. [Figure 4] 10(a), (b), and (c) are diagrams for explaining the operation of the prism portion. [Figure 5] 10 is a graph showing the relationship between the rotation angle of the prism portion and the shift amount of the optical image of the sample on the imaging surface of the imaging element. [Figure 6] 6 is an enlarged graph of the first quadrant of the graph shown in FIG. 5. [Figure 7] 1A is a schematic diagram showing an example of movement of the field position of the objective lens, and FIG. 1B is a schematic diagram showing another example of movement of the field position of the objective lens. [Figure 8] 1A is a diagram showing an example of a prism part, and FIG. 1B is a graph showing the relationship between the rotation angle of the prism part and the shift amount of the optical image of the sample on the imaging surface of the imaging element. [Figure 9]10A is a graph showing the irradiation time of irradiation light in an optical imaging device according to a comparative example, and FIG. 10B is a graph showing the irradiation time of irradiation light in an optical imaging device according to an embodiment. [Figure 10] 10A, 10B, and 10C are diagrams for explaining image acquisition in an optical imaging device according to a comparative example. [Figure 11] 10A and 10B are diagrams illustrating the shift of light onto the optical axis in the optical system according to the embodiment. [Figure 12] FIG. 10 is a diagram showing a light irradiation device to which an optical system according to a first modified example is applied. [Figure 13] FIG. 10 is a diagram showing a light irradiation device to which an optical system according to a second modified example is applied. [Figure 14] FIG. 10 is a diagram showing an optical system according to a third modified example. [Figure 15] FIG. 10 is a diagram showing an optical system according to a fourth modified example. [Figure 16] FIG. 10 is a diagram showing an optical system according to a fifth modified example. DETAILED DESCRIPTION OF THE INVENTION

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same or equivalent elements are designated by the same reference numerals, and redundant description will be omitted.

[0019] As shown in FIG. 1 , the optical imaging device 1 includes a stage 2, a light output unit 3, an optical system 4, an image sensor 5 (image sensor), a drive unit 6, a rotation mechanism 7, and a control unit 8. For example, the optical imaging device 1 is a virtual slide scanner that images a sample S on a glass slide (not shown) using a strobe scanning method. In the strobe scanning method, the glass slide (sample S) is moved in one direction while being irradiated with instantaneous light (strobe light), and light generated from the sample S in response to the irradiation of the instantaneous light is imaged. As an example, in the optical imaging device 1, a stage 2 on which the sample S (glass slide) is placed is moved horizontally by a drive unit 6. Irradiation light L0 is irradiated onto the sample S from the optical output unit 3, and light L from the sample S in response to the irradiation is guided to an imaging surface 5a of the image sensor 5 by the optical system 4. The image sensor 5 captures the light L from the sample S to obtain an image of the sample S. Hereinafter, the moving direction of the stage 2 (the scanning direction of the irradiated light L0 on the sample S) is referred to as direction D1, and the direction along the path of the light L from the sample S to the imaging surface 5a is referred to as direction D4.

[0020] The sample S observed by the optical imaging device 1 is, for example, a biological sample such as tissue cells, and is placed on the surface of the stage 2 while sealed in a slide glass. The light output unit 3 is disposed on the back side of the stage 2 (the side opposite the objective lens 41). The light output unit 3 has a light source 3a that outputs irradiating light L0 to the sample S. In this example, the light output unit 3 switches the output of the irradiating light L0 on and off by controlling the on / off of the light source 3a. The light source 3a is, for example, a light source that emits instantaneous light (strobe light). For example, a laser diode (LD), a light-emitting diode (LED), a superluminescent diode (SLD), or a flash lamp type light source such as a xenon flash lamp may be used as the light source 3a.

[0021] The optical system 4 guides an optical image of the sample S to the image sensor 5. The optical system 4 has an objective lens 41 (second lens), an optical deflection unit 42, and an imaging lens 43 (first lens). The objective lens 41 is a lens through which light L from the sample S passes. The optical deflection unit 42 deflects the light L from the sample S that has passed through the objective lens 41, thereby guiding the light L from the sample S to the imaging surface 5a of the image sensor 5. The imaging lens 43 is, for example, a tube lens, and forms an image of the light L from the sample S deflected by the optical deflection unit 42 on the imaging surface 5a of the image sensor 5. In the example shown in FIG. 1, the objective lens 41, the optical deflection unit 42, the imaging lens 43, and the imaging surface 5a are arranged in this order on the path of the light L from the sample S to the imaging surface 5a. Light L from the sample S passes through the objective lens 41, and then passes through the prism section 50, which is the light deflection section 42, and is then imaged on the imaging surface 5a by the imaging lens 43. The prism section 50 will be described in detail later.

[0022] Light L from the sample S is generated when illumination light L0 is irradiated onto the sample S. The illumination light L0 is not diffused light, but rather a beam of light with a certain directionality. The light L from the sample S is focused on the imaging surface 5a of the image sensor 5 to form an optical image of the sample S. The optical image of the sample S is an image of transmitted light in the case of bright-field illumination, scattered light in the case of dark-field illumination, or luminescence (fluorescence) in the case of luminescence measurement. It may also be an image of reflected light from the sample S. In these cases, an optical system capable of acquiring a transmitted light image of the sample S, a scattered light image of the sample S, and a luminescence (fluorescence) image of the sample S can be adopted as the optical system 4.

[0023] The imaging element 5 captures an image of the light L from the sample S (light L from the optical system 4) guided by the optical system 4. The imaging element 5 has a plurality of pixels on the imaging surface 5a. In this embodiment, the imaging element 5 is a two-dimensional imaging element (area sensor) having a plurality of pixel rows on the imaging surface 5a. The imaging element 5 may be, for example, a CCD image sensor or a CMOS image sensor. The imaging element 5 sequentially captures light images of the sample S guided by the optical system 4 at a predetermined frame rate.

[0024] As shown in FIG. 4, a plurality of pixel columns Q are arranged along a direction D3 (arrangement direction) on the imaging surface 5a of the imaging element 5. Each pixel column Q is made up of a plurality of pixels arranged along a direction perpendicular to the direction D3 (the left-right direction in the drawing). That is, the imaging surface 5a has a plurality of pixels arranged in a two-dimensional (matrix) pattern. The plurality of pixel columns Q are a first pixel column Q1, a second pixel column Q2, a third pixel column Q3, ..., an (M-1)th pixel column Q. M-1 and M pixel columns Q M The direction D3 corresponds to the direction D1 (the direction in which the field of view position of the objective lens 41 moves relative to the sample S). For example, when the stage 2 moves in the direction D1 and the field of view position P of the objective lens 41 moves on the sample S along the direction D1 (the opposite direction to the direction D1), the optical image of the sample S moves on the imaging surface 5a of the image sensor 5 along the direction D3.

[0025] Referring again to Figure 1, the driving unit 6 moves the field of view position P of the objective lens 41 relative to the sample S. Specifically, the driving unit 6 moves the sample S fixed to the surface of the stage 2 in a direction D1 perpendicular to the direction D4, thereby moving the field of view position P along the direction D1 (in the opposite direction to the direction D1). For example, the driving unit 6 is configured by a stepping motor (pulse motor), a piezoelectric actuator, or the like.

[0026] The rotation mechanism 7 rotates the light deflection unit 42 around a central axis perpendicular to the direction D4. In the example shown in Fig. 1, the light deflection unit 42 is a prism unit 50. The rotation mechanism 7 includes, for example, a motor as a drive source.

[0027] The control unit 8 physically includes memories such as RAM and 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. Examples of the control unit 8 include a personal computer, a microcomputer, and a smart device (smartphone, tablet terminal, etc.). For example, the control unit 8 controls the light deflection unit 42 via the rotation mechanism 7. In this embodiment, the control unit 8 controls the rotation mechanism 7 to control the rotation angle of the light deflection unit 42 (prism unit 50) (e.g., the rotation angle θ1 around the central axis of the first prism). In this example, the control unit 8 also controls and processes other elements in the optical imaging device 1. For example, the control unit 8 may control the on / off of the output of the illumination light L0 by the light output unit 3, control the imaging by the image sensor 5, and control the movement of the field of view position P of the objective lens 41 relative to the sample S by the drive unit 6. The control unit 8 may also perform image generation processing based on signals acquired by the image sensor 5. [Optical system configuration]

[0028] Next, the optical system 4 will be described with reference to Fig. 2. Fig. 2 is a diagram showing the optical system 4 according to the embodiment. As described above, the optical system 4 is an imaging optical system that can be applied to an optical imaging device 1 (e.g., a virtual slide scanner) that images a sample S that moves on a stage 2 or the like.

[0029] The optical system 4 is an optical system having a parallel light path portion P1. First, the parallel light path portion P1 will be described with reference to FIG. 3. The parallel light path portion P1 is a portion through which light L travels as parallel light. The "portion through which light travels as parallel light" refers to "a portion through which light travels with all light rays contained in the light parallel to each other." FIG. 3 omits the light deflection unit 42 and schematically illustrates the optical system 4 including an objective lens 41 and an imaging lens 43. In the example shown in FIG. 3, light L1, L2 (L) from the sample S passes through the objective lens 41 (second lens) and the imaging lens 43 (first lens) to reach the imaging surface 5a (imaging unit) of the imaging element 5. In this example, the optical axis direction of the parallel light path portion P1 is parallel to a straight line (optical axis) passing through the center C41 of the objective lens 41 and the center C43 of the imaging lens 43, e.g., direction D4. Light L1 and L2 from the sample S are light from different positions T1 and T2 on the sample S, respectively. Light L1 and L2 travel as parallel light between the objective lens 41 and the imaging lens 43, and as convergent light between the imaging lens 43 and the imaging plane 5a. In this case, light L1 travels parallel to direction D4 in the parallel light path portion P1. Light L2 travels in a direction intersecting direction D4 in the parallel light path portion P1. In this way, light L traveling as parallel light through the parallel light path portion P1 may travel parallel to the optical axis direction of the parallel light path portion P1, or may travel in a direction intersecting the optical axis direction of the parallel light path portion P1.

[0030] Referring again to FIG. 2, the objective lens 41 (second lens) receives light L from the sample S and then outputs the light L, which travels as parallel light, to the parallel light path portion P1. In this example, the light L from the sample S is collimated by the objective lens 41 to become parallel light (collimated light). The light L output to the parallel light path portion P1 passes through the light deflection unit 42 and enters the imaging lens 43. The imaging lens 43 focuses the light L from the light deflection unit 42 (prism unit 50). For example, the imaging lens 43 (first lens) forms an image of the light L from the light deflection unit 42.

[0031] The light deflection unit 42 is a prism unit 50 that refracts light L. The prism unit 50 is arranged in the parallel light path portion P1. The prism unit 50 is arranged between the imaging lens 43 and the objective lens 41 on the optical path of light L from the sample S. The prism unit 50 deflects light L from the sample S that has passed through the objective lens 41 by refracting it. Hereinafter, in Figures 1 and 2, directions that are perpendicular to direction D4 and that are perpendicular to each other are referred to as direction D5 and direction D6.

[0032] The prism section 50 will be described with reference to Fig. 2. The prism section 50 has a first prism 51 and a second prism 52 aligned along direction D4. Light L traveling as parallel light in parallel optical path portion P1 is incident on the prism section 50. The light L that has passed through the prism section 50 is emitted toward the imaging lens 43.

[0033] The first prism 51 includes a first surface 51a and a second surface 51b inclined relative to the first surface 51a. The first prism 51 is, for example, a wedge prism. Light L from the sample S is incident on the first surface 51a of the first prism 51. The light L incident on the first surface 51a passes through the first prism 51 and exits from the second surface 51b. The first prism 51 refracts the light L from the sample S at at least one of the first surface 51a and the second surface 51b. The first prism 51 is formed, for example, from a material (such as borosilicate glass (BK7)) that transmits the light L from the sample S.

[0034] The second prism 52 includes a third surface 52a and a fourth surface 52b inclined relative to the third surface 52a. The second prism 52 is, for example, a wedge prism. The light L from the first prism 51 is incident on the third surface 52a of the second prism 52. The light L incident on the third surface 52a passes through the second prism 52 and exits from the fourth surface 52b. The second prism 52 refracts the light L from the sample S at at least one of the third surface 52a and the fourth surface 52b. The second prism 52 is formed of, for example, a material (such as borosilicate glass (BK7)) that transmits the light L from the sample S. The second prism 52 may be the same prism as the first prism 51, or may be a prism different from the first prism 51.

[0035] The inclination angle of the second surface 51b relative to the first surface 51a corresponds to the inclination angle of the fourth surface 52b relative to the third surface 52a. For example, the inclination angle of the second surface 51b relative to the first surface 51a is substantially the same as the inclination angle of the fourth surface 52b relative to the third surface 52a.

[0036] The first prism 51 is rotatable about a central axis extending along direction D6 (a central axis intersecting the optical axis direction). The rotation angle θ1 is the tilt angle of the first surface 51a of the first prism 51 with respect to the horizontal direction (e.g., direction D1) (see FIG. 4). The orientation of the first prism 51 with respect to the second prism 52 changes depending on the rotation angle θ1 of the first prism 51. Specifically, when the rotation angle θ1 of the first prism 51 is 0 degrees (see FIG. 2), the second surface 51b is located on the second prism 52 side, and the first surface 51a is located on the opposite side from the second prism 52. The third surface 52a is located on the first prism 51 side, and the fourth surface 52b is located on the opposite side from the first prism 51. The first surface 51a is parallel to the fourth surface 52b, and the second surface 51b is parallel to the third surface 52a. In this case, the first prism 51 and the second prism 52 are positioned so as to form a parallelogram-shaped (rectangular in this example) flat plate (parallel flat plate) when they are brought close to each other along direction D4 and the second surface 51b and the third surface 52a are brought into contact with each other. The first prism 51 can rotate 360 ​​degrees around the central axis.

[0037] The first prism 51 refracts the light L from the sample S at at least one of the first surface 51a and the second surface 51b. Specifically, the first surface 51a and the second surface 51b refract the light L when the light L is incident at an angle other than 90 degrees. In the example shown in FIGS. 4(a) and 4(b), the first prism 51 refracts the light L from the sample S at both the first surface 51a and the second surface 51b. In the example shown in FIG. 2, the incident angle of the light L from the sample S at the first surface 51a of the first prism 51 is 90 degrees, so the first prism 51 does not refract the light L from the sample S at the first surface 51a, but refracts the light L from the sample S only at the second surface 51b.

[0038] The second prism 52 refracts the light L from the sample S at at least one of the third surface 52a and the fourth surface 52b. Specifically, the third surface 52a and the fourth surface 52b refract the light L when the light L is incident at an angle other than 90 degrees. In the example shown in FIGS. 4(a) and 4(b), the second prism 52 refracts the light L from the sample S at both the third surface 52a and the fourth surface 52b. In the example shown in FIG. 2, the incident angle of the light L from the sample S at the fourth surface 52b of the second prism 52 is 90 degrees, so the light L from the sample S is not refracted at the fourth surface 52b, and the light L from the sample S is refracted only at the third surface 52a.

[0039] According to the optical system 4 described above, by changing the rotation angle θ1 of the first prism 51, when the light L is refracted at the prism section 50, the light L shifts along the direction D5. This makes it possible to shift the focusing position P50 of the light L on the imaging surface 5a along the direction D3. For example, by rotating the first prism 51 counterclockwise, it is possible to shift the focusing position P50 of the light L to one side in the direction D3 on the imaging surface 5a. Furthermore, for example, by rotating the first prism 51 clockwise, it is possible to shift the focusing position P50 of the light L to the other side in the direction D3 on the imaging surface 5a. [Operation of optical imaging device]

[0040] FIG. 4 is a diagram for explaining the operation of the light deflection unit 42, which is the prism unit 50. For the sake of explanation, FIG. 4 illustrates the imaging surface 5a facing the front side of the page. FIG. 4 illustrates only one divided region R out of the multiple divided regions R shown in FIG. 1. First, an overview of the image acquisition operation by the optical imaging device 1 will be described. The optical imaging device 1 acquires an image of the sample S during an image acquisition period. Here, the optical imaging device 1 images the sample S at a magnification of, for example, 20 times or more and 40 times or less, and therefore the field of view of the objective lens 41 is smaller than the sample S. Therefore, in order to image the entire sample S, it is necessary to image the sample S while moving the field of view position P of the objective lens 41 relative to the sample S.

[0041] Specifically, in the optical imaging device 1, during an image acquisition period, the driving unit 6 moves the field of view position P of the objective lens 41 relative to the sample S, while the light output unit 3 outputs the irradiated light L0, and the image sensor 5 captures the light L from the sample S. More specifically, first, an image acquisition region is set to include the entire sample S. Next, multiple divided regions (divided regions R shown in FIG. 1 ) are set by dividing the image acquisition region based on the size of the field of view of the objective lens 41. During the image acquisition period, the field of view position P of the objective lens 41 relative to the sample S is moved so as to pass through all the divided regions, while capturing images of light from each divided region. At this time, light from each region (region A shown in FIG. 4(a)) of the divided region is captured by each of the multiple pixel arrays Q. As a result, partial images corresponding to each divided region are sequentially captured. Finally, the acquired partial images are combined to generate an entire image of the sample S, thereby capturing an image of the sample S.

[0042] 1 and 4, the field of view position P of the objective lens 41 is moved so as to pass through a plurality of divided regions R aligned along the direction D1, and light from each divided region R is captured. In this example, as shown in FIG. 4, each divided region R includes M regions A aligned along the direction D1, and these M regions A are grouped into a first pixel column Q1 to an M-th pixel column Q2. M Each image is captured by

[0043] Next, the image acquisition timing of the optical imaging device 1 during the image acquisition period will be described. The image acquisition period includes multiple imaging periods and multiple non-imaging periods. The imaging periods and non-imaging periods are repeated alternately. During each imaging period, an image is acquired by the optical imaging device 1. During each non-imaging period, the optical imaging device 1 prepares to acquire the next image.

[0044] For example, when the field of view position P of the objective lens 41 is located in a certain divided region R during a certain imaging period, irradiating light L0 is output from the light output unit 3 to the divided region R, and the light L from the divided region R is imaged by the image sensor 5. When the field of view position P of the objective lens 41 moves onto another divided region R, the next imaging period begins. During the next imaging period, irradiating light L0 is output from the light output unit 3 to another divided region R, and the light L from the other divided region R is imaged by the image sensor 5. During the non-imaging period, which is the period between one imaging period and the next imaging period, preparations are made to start the next imaging period.

[0045] Next, the operation of each unit during the imaging period will be described. The control unit 8 controls the light deflection unit 42 in accordance with (synchronization with) the movement of the sample S. Specifically, the control unit 8 controls the rotation angle θ1 of the first prism 51 so that the first surface 51a of the first prism 51 follows the movement of the sample S. In the example shown in FIG. 4, the control unit 8 changes the rotation angle θ1 of the first prism 51 in synchronization with the movement of the sample S, thereby causing the light LA ​​from the region A in the divided region R to continue to be incident on one pixel row Q (the second pixel row Q2 in this example) on the imaging surface 5a of the image sensor 5 throughout the imaging period. As a result, the light LA ​​from the same region (region A) on the sample S continues to be incident on the same region (the second pixel row Q2) on the imaging surface 5a.

[0046] First, as shown in FIG. 4(a), light LA ​​from region A in the divided region R is guided to the second pixel row Q2 on the imaging surface 5a of the image sensor 5 during the imaging period. Next, as shown in FIG. 4(b), as the sample S moves, the first prism 51 rotates so that the first surface 51a follows the sample S. Finally, as shown in FIG. 4(c), as the sample S continues to move, the prism unit 50 further rotates so that the first surface 51a follows the sample S. In this manner, the control unit 8 controls the prism unit 50 by rotating the first prism 51 of the prism unit 50 in synchronization with the movement of the sample S. As a result, light LA ​​from the same region (region A) on the sample S continues to be incident on the same region (second pixel row Q2) on the imaging surface 5a. This makes it possible to prevent light L from the sample S from moving on the imaging surface 5a, even though the sample S is moving. As a result, during the imaging period, the time for outputting the irradiating light L0 can be set to, for example, a time equivalent to three pixels (a time three times longer than the reference time equivalent to one pixel, described below), and the intensity of the imaged light L can be tripled compared to when the irradiating light L0 is output for a time equivalent to one pixel to obtain an image.

[0047] As described above, the control unit 8 controls the light deflection unit 42 so that the light LA ​​from the same region (region A) on the sample S is incident on the same region (same pixel row Q) on the imaging surface 5a of the image sensor 5 during the imaging period of the image acquisition period. The light output unit 3 outputs the illumination light L0 for a time longer than the reference time during the imaging period. For example, the light output unit 3 outputs the illumination light L0 for a time at least twice the reference time during the imaging period. Here, the reference time is the time required for the field of view position P of the objective lens 41 to move an amount corresponding to one pixel (one pixel row Q) along the direction D1. For example, when the rotation angle θ1 of the first prism 51 is constant and the field of view position P of the objective lens 41 moves by the reference time, the optical image of the sample S on the imaging surface 5a of the image sensor 5 moves a distance equivalent to one pixel (the width of the pixel row Q in the direction D3).

[0048] The control unit 8 rotates (oscillates) the first prism 51 in one direction and the other direction during the image acquisition period. Specifically, the control unit 8 periodically switches the rotation direction of the first prism 51 to oscillate the first prism 51. For example, the control unit 8 causes the light output unit 3 to output the illumination light L0 and rotate the first prism 51 in one direction during the image acquisition period. The control unit 8 stops the output of the illumination light L0 from the light output unit 3 and rotates the first prism 51 in the other direction during the non-image acquisition period. Note that the control unit 8 may continue to rotate the first prism 51 in one direction during the image acquisition period. In this case, the control unit 8 continues to rotate the first prism 51 in the same direction and controls the light output unit 3 to emit the illumination light L0 at a timing when the rotation angle θ1 of the first prism 51 falls within a predetermined numerical range.

[0049] Next, a simulation result of the change in the shift amount of the optical image of the sample S on the imaging surface 5a of the image sensor 5 with respect to the change in the rotation angle θ1 of the first prism 51 will be described. FIGS. 5 and 6 are graphs showing the simulation result of the relationship between the rotation angle θ1 of the first prism 51 and the shift amount of the optical image of the sample S on the imaging surface 5a of the image sensor 5. The horizontal axis of FIG. 5 represents the rotation angle θ1 of the first prism 51, and the vertical axis of FIG. 5 represents the shift amount of the optical image of the sample S on the imaging surface 5a of the image sensor 5. FIG. 6 is a graph showing an enlarged first quadrant of the graph shown in FIG. 5. Graphs G6 to G9 are graphs showing the above-mentioned relationship in the optical imaging device 1 when the tilt angle of the second surface 51b with respect to the first surface 51a in the prism section 50 is changed in various ways. The tilt angles of the multiple first prisms 51 corresponding to graphs G6, G7, G8, and G9 are 1 degree, 2 degrees, 3 degrees, and 5 degrees, respectively.

[0050] 5 and 6, the shift amount of the optical image of the sample S on the imaging plane 5a changes nonlinearly with the rotation angle θ1 of the first prism 51. As the rotation angle θ1 of the first prism 51 changes, the shift amount of the optical image of the sample S decreases and then increases. Thus, the sensitivity of the shift amount of the optical image of the sample S to the change in the rotation angle θ1 of the first prism 51 depends on the absolute value of the rotation angle θ1 of the first prism 51. For example, when comparing the case where the rotation angle θ1 of the first prism 51 is 0 degrees or more and 1 degree or less (part G91 of graph G9), the case where the rotation angle θ1 of the first prism 51 is 2 degrees or more and 3 degrees or less (part G92 of graph G9), and the case where the rotation angle θ1 of the first prism 51 is 5 degrees or more and 6 degrees or less (part G93 of graph G9), the shift amount of the imaging position of the optical image with respect to the change in the rotation angle θ1 increases as the rotation angle θ1 of the first prism 51 increases. This makes it possible to adjust the sensitivity of the shift in the optical image position relative to the change in the rotation angle θ1 of the first prism 51 by appropriately selecting the range of the rotation angle θ1 of the first prism 51 used to adjust the optical image position.

[0051] The sensitivity of the shift amount of the optical image of the sample S with respect to the change in the rotation angle θ1 of the first prism 51 also depends on the tilt angle of the second surface 51b with respect to the first surface 51a. The larger the tilt angle of the second surface 51b with respect to the first surface 51a of the first prism 51, the larger the shift amount of the optical image of the sample S with respect to the rotation angle θ1 of the first prism 51.

[0052] Next, with reference to FIGS. 7 and 8, the operation of the prism unit 50 in response to movement of the field of view position P of the objective lens 41 in the optical imaging device 1 according to the embodiment will be described. FIG. 7(a) is a schematic diagram showing an example of movement of the field of view position P of the objective lens 41. FIG. 7(b) is a schematic diagram showing another example of movement of the field of view position P of the objective lens 41. In the example shown in FIGS. 7(a) and 7(b), the sample S has a rectangular shape. One side of the sample S in the longitudinal direction is the X1 side, and the other side of the sample S in the longitudinal direction is the X2 side. One side of the sample S in the lateral direction is the X3 side, and the other side of the sample S in the lateral direction is the X4 side. FIG. 8(a) is a diagram showing an example of the prism unit 50. FIG. 8(b) is a graph showing a simulation result of the relationship between the rotation angle θ1 of the first prism 51 and the shift amount of the optical image of the sample S on the imaging plane 5a of the image sensor 5. The horizontal axis of FIG. 8(b) represents the rotation angle θ1 of the first prism 51, and the vertical axis of FIG. 8(b) represents the shift amount of the optical image of the sample S on the imaging surface 5a of the imaging element 5.

[0053] First, the movement of the field of view position P of the objective lens 41 will be described. In the example shown in Fig. 7(a), the stage 2 is moved so as to move the field of view position P of the objective lens 41 toward the X1 side. When one movement is completed, the stage 2 is moved so that the field of view position P of the objective lens 41 moves a predetermined distance toward the X4 side. This allows the field of view position P of the objective lens 41 to be repeatedly moved toward the X1 side while the field of view position P of the objective lens 41 is sequentially moved toward the X4 side (single-axis scanning).

[0054] 7(b), the stage 2 is moved so that the field of view position P of the objective lens 41 is moved alternately to the X1 side and the X2 side. At the timing when one movement to the X1 side or the X2 side is completed, the stage 2 is moved so that the field of view position P of the objective lens 41 is moved a predetermined distance to the X4 side. In this way, the reciprocating movement of the field of view position P of the objective lens 41 can be repeatedly performed while the field of view position P of the objective lens 41 is sequentially moved to the X4 side (reciprocating scan).

[0055] Next, the operation of the prism unit 50 will be described. In the example shown in FIG. 8(a), the first prism 51 rotates clockwise. At this time, in the graph shown in FIG. 8(b), the numerical values ​​on the horizontal axis change from the left side of the paper to the right side of the paper (in the direction A1 in FIG. 8(b)). In the example shown in FIG. 8(b), when the rotation angle θ1 increases in the first range RP, which is the range in which the rotation angle θ1 is positive, the shift amount of the optical image of the sample S increases. When the rotation angle θ1 increases in the second range RN, which is a predetermined range in which the rotation angle θ1 is negative, the shift amount of the imaging position of the optical image decreases.

[0056] Finally, the operation of the prism unit 50 in response to movement of the field of view position P will be described. For example, when the control unit 8 moves the field of view position P of the objective lens 41 toward the X1 side (see FIGS. 7(a) and 7(b)), the control unit 8 irradiates the sample S with the illumination light L0 while increasing the rotation angle θ1 in the first range RP (see FIG. 8(b)). This allows the control unit 8 to move the field of view position P of the objective lens 41 toward the X1 side while causing light from the same region on the sample S to be incident on the same region on the imaging surface 5a of the image sensor 5.

[0057] Furthermore, for example, when the control unit 8 moves the field of view position P of the objective lens 41 toward the X2 side (see FIG. 7(b)), the control unit 8 irradiates the sample S with the illumination light L0 while increasing the rotation angle θ1 in the second range RN (see FIG. 8(b)). In this way, the control unit 8 can move the field of view position P of the objective lens 41 toward the X2 side while causing light from the same region on the sample S to be incident on the same region on the imaging surface 5a of the imaging element 5.

[0058] As described above, the timing of irradiating the illumination light L0 (the phase of the LED light emission cycle) is controlled while rotating the first prism 51 in one direction (at a constant speed). This allows the sample S on the stage 2 to be scanned toward either the X1 side or the X2 side, or toward both the X1 side and the X2 side, while causing light from the same region on the sample S to be incident on the same region on the imaging surface 5a of the image sensor 5 while rotating the first prism 51 in one direction. [Action and effect]

[0059] The optical imaging device 1 includes an optical deflection unit 42 that deflects light L from the sample S that has passed through the objective lens 41. During an imaging period during an image acquisition period, the optical deflection unit 42 is controlled so that light from the same region on the sample S is incident on the same region on the imaging surface 5a of the image sensor 5. This prevents light L from the sample S from being incident on multiple pixels, even if the time during which the optical output unit 3 outputs the irradiated light L0 during the imaging period is set longer than the time (reference time) required for the field of view position P of the objective lens 41 relative to the sample S to move by an amount corresponding to one pixel on the image sensor 5. Therefore, for example, the time during which the optical output unit 3 outputs the irradiated light L0 during the imaging period can be set longer than the reference time, thereby ensuring sufficient intensity of the imaged light. For example, the time during which the irradiated light L0 is output can be set to a time equivalent to N pixels, thereby increasing the intensity of the light L from the sample S by approximately N times. Therefore, the optical imaging device 1 can acquire clear images while suppressing image blur.

[0060] The above points will be further explained with reference to FIGS. 9 and 10. FIG. 9(a) is a graph showing the irradiation time of light emitted by the light output unit of an optical imaging device according to a comparative example. FIG. 9(b) is a graph showing the irradiation time of light emitted by the light output unit 3 of the optical imaging device 1 according to the embodiment. FIGS. 10(a), 10(b), and 10(c) are diagrams for explaining image acquisition in the optical imaging device according to the comparative example. FIGS. 10(a), 10(b), and 10(c) show a sample S moving in one direction, an objective lens 1041 arranged opposite the sample S, and an area sensor 1005 that captures light L from the sample S that has passed through the objective lens 1041. The arrows on the sample S indicate portions S1, S2, and S3 of the sample S. The arrows next to the area sensor 1005 indicate light images S20 to S23 of a portion S2 of the sample S formed on the imaging surface 1005a of the area sensor 1005. The hatched sample S in FIG. 10(c) indicates that no irradiation light was output at that timing.

[0061] As shown in FIG. 9(a), in the optical imaging device according to the comparative example, the irradiation time T0 of the irradiation light is set to be equal to or shorter than the reference time. In FIG. 9(a), the irradiation time T0 of the irradiation light is set to be the same length as the reference time. More specifically, as shown in FIG. 10(a), in the optical imaging device, in order to image the sample S at high speed, imaging may be performed while moving the sample S at a constant speed. However, in this case, as shown in FIG. 10(b), the optical image S20 formed on the imaging surface 1005a of the area sensor 1005 also moves at a constant speed (optical images S21, S22, and S23), which may cause blurring in the image captured by the area sensor 1005, resulting in a blurred image. Therefore, as shown in FIG. 10(c), it is conceivable to suppress image blurring by setting the irradiation time of the irradiation light to the time corresponding to one pixel. However, in this case, the intensity of the captured light may be insufficient, and a sufficiently clear image may not be obtained. In contrast to this, as shown in FIG. 9(b), in the optical imaging device 1 of this embodiment, the irradiation time T0 during which the light output unit 3 outputs the irradiation light L0 during the imaging period can be set to be longer than the reference time (the time corresponding to one pixel), and a clear image can be obtained while suppressing blurring of the image.

[0062] The light output unit 3 outputs the irradiated light L0 for a time longer than the reference time during the imaging period. In this case, it is possible to ensure a sufficient intensity of the light used for imaging. Furthermore, the light output unit 3 outputs the irradiated light L0 for a time at least twice the reference time during the imaging period. In this case, it is possible to ensure an even more sufficient intensity of the light used for imaging.

[0063] The prism section 50 (light deflection section 42) deflects the light L from the sample S that has passed through the objective lens 41 by refracting it, and the control section 8 rotates the prism section 50 during an imaging period during an image acquisition period so that light from the same region on the sample S is incident on the same region on the imaging surface 5a of the imaging element 5. In this case, the light deflection section 42 can be configured by the prism section 50 that refracts the light L.

[0064] The prism section 50 (optical element) is disposed between the objective lens 41 and the imaging lens 43 on the optical path of the light L from the sample S. In this case, by adjusting the material or thickness of the prism section 50, it is possible to adjust the sensitivity of the change in the imaging position of the optical image formed on the imaging surface 5a of the image sensor 5 to the change in the rotation angle θ1 of the first prism 51. Furthermore, since this sensitivity is relatively low compared to when, for example, an optical deflection section 42 having a reflective surface is configured, it is possible to easily control the amount of change in the position of the optical image by controlling the rotation angle of the prism section 50 (control of the rotation angle).

[0065] The optical system 4 is provided with a prism section 50 having a first prism 51 including a first surface 51a and a second surface 51b inclined relative to the first surface 51a. Light traveling as parallel light along the parallel optical path portion P1 enters the prism section 50, and the prism section 50 refracts the light L at at least one of the first surface 51a and the second surface 51b. The first prism 51 is rotatable about a central axis intersecting the optical axis direction (direction D4). With this configuration, by changing the rotation angle θ1 around the central axis of the first prism 51, for example, the light L output from the optical system 4 can be shifted (moved) relative to the optical axis A41 along a direction intersecting the optical axis direction (direction D5 intersecting the direction D4). When light L shifted relative to the optical axis A41 along a direction intersecting the optical axis direction (direction D5 intersecting the direction D4) is input to the optical system 4, the light L can be shifted onto the optical axis A41 and output. Therefore, according to the optical system 4 of this embodiment, it is possible to shift the relative position between the input light and the output light along a direction intersecting the optical axis direction (direction D5 intersecting with direction D4) with a simple configuration.

[0066] The above-described effects will be described with reference to FIG. 11. FIG. 11(a) is a diagram illustrating a shift of light L relative to the optical axis A41 in the optical system 4 according to the embodiment. FIG. 11(b) is a diagram illustrating a shift of light L onto the optical axis A41. In the example illustrated in FIG. 11(a), when light L traveling along the optical axis A41 of the objective lens 41 is input to the optical system 4, the light is focused onto the optical axis A41 of the objective lens 41 on the imaging surface 5a of the image sensor 5. On the other hand, when light L shifted along direction D5 relative to the optical axis A41 of the objective lens 41 is input to the optical system 4, if the traveling direction of the light L is not parallel to the optical axis A41 between the prism section 50 and the imaging lens 43, the focusing position P50 of the light L will be shifted from the optical axis A41. In this case, by rotating the first prism 51 clockwise to make the traveling direction of the light L parallel to the optical axis A41 between the prism section 50 and the imaging lens 43, it is possible to shift the focusing position P50 of the light L onto the optical axis A41. In the example shown in FIG. 11(b), when the light L traveling on the optical axis A41 of the objective lens 41 is input to the optical system 4, if the traveling direction of the light L is parallel to the optical axis A41 between the prism section 50 and the imaging lens 43, the light L is focused onto the optical axis A41 of the objective lens 41 on the imaging surface 5a of the image sensor 5. In this case, by rotating the first prism 51 clockwise, it is possible to make the traveling direction of the light L not parallel to the optical axis A41 between the prism section 50 and the imaging lens 43, it is possible to shift the focusing position P50 of the light L from onto the optical axis A41.

[0067] The second prism 52 refracts the light L from the sample S at at least one of the third surface 52a and the fourth surface 52b. In this case, for example, dispersion caused by refraction in the first prism 51 can be reduced by refraction in the second prism 52. In addition, for example, the second prism 52 can also shift the light L along a direction intersecting the optical axis direction (direction D5 intersecting with direction D4).

[0068] The above-mentioned effects will be explained. First, the fact that dispersion caused by refraction in the first prism 51 can be reduced by refraction in the second prism 52 will be explained. As an optical system according to a comparative example, consider a case where a prism unit having only one prism is provided. In this case, light propagating in different directions for each wavelength by the prism unit is imaged at different positions for each wavelength on the imaging surface of the imaging element by the imaging lens. This may cause color shift in the image captured by the imaging element. In contrast, in this embodiment, the prism unit 50 has the first prism 51 and the second prism 52, so that color shift in the image captured by the imaging element 5 caused by the first prism 51 can be corrected by the second prism 52.

[0069] Next, it will be described how the second prism 52 can also shift the light L in a direction intersecting the optical axis direction (direction D4). For example, when the second surface 51b is located on the second prism 52 side and the first surface 51a is located on the opposite side from the second prism 52 (see FIG. 9(a)), the light L shifted to one side in direction D5 by the first prism 51 can be shifted to the other side in direction D5 by the second prism 52. Furthermore, when the first surface 51a is located on the second prism 52 side and the second surface 51b is located on the opposite side from the second prism 52, the light L shifted to one side in direction D5 by the first prism 51 can be further shifted to one side in direction D5 by the second prism 52.

[0070] When the rotation angle θ1 of the first prism 51 around the central axis is a certain angle, the second surface 51b is located on the second prism 52 side, and the first surface 51a is located on the opposite side from the second prism 52. The third surface 52a is located on the first prism 51 side, and the fourth surface 52b is located on the opposite side from the first prism 51. The first surface 51a is parallel to the fourth surface 52b, and the second surface 51b is parallel to the third surface 52a. In this case, it is possible to preferably achieve the effects of reducing dispersion caused by refraction in the first prism 51 by refraction in the second prism 52, and shifting the light L along a direction intersecting the optical axis direction (direction D5 intersecting with direction D4) by the second prism 52 as well.

[0071] The objective lens 41 outputs the light L traveling as parallel light to the parallel light path portion P1. The imaging lens 43 forms an image of the light L from the prism portion 50. In this case, in the optical system 4, which is an imaging optical system, it is possible to shift the relative position between the input light and the output light (imaging position) along a direction intersecting the optical axis direction (direction D5 intersecting with direction D4) with a simple configuration.

[0072] In the optical imaging device 1 of this embodiment, the control unit 8 controls the rotation angle θ1 about the central axis of the first prism 51. In this case, by changing the rotation angle θ1 about the central axis of the first prism 51, for example, it is possible to shift the imaging position on the imaging surface 5a of the image sensor 5 (imaging unit) relative to the optical axis A41 along a direction intersecting the optical axis direction (direction D5 intersecting with direction D4), or when light shifted relative to the optical axis A41 along a direction intersecting with the optical axis direction (direction D5 intersecting with direction D4) is input to the optical system 4, it is possible to shift the light L onto the optical axis A41 and then form an image on the imaging surface 5a.

[0073] The optical system 4 is an optical system (transmission type optical system) that transmits light L incident on the optical system 4. For example, if the optical system is a reflective optical system that reflects incident light, the optical path changes by 90 degrees in the optical system, and therefore, when incorporating the optical system into an existing system, it is necessary to change the arrangement of the imaging lens and image sensor in the downstream stage of the optical system, or the sample and objective lens in the upstream stage of the optical system. However, if the optical system 4 is a transmission type optical system, this is not necessary, and it is possible to easily incorporate the optical system into an existing system. [First Modification]

[0074] Up to this point, the optical imaging device 1 to which the optical system 4 is applied has been described. Below, a light irradiation device 101 to which the optical system 104 according to the first modified example is applied will be described. Fig. 12 is a diagram showing the light irradiation device 101 to which the optical system 104 according to the first modified example is applied. While the optical system 4 according to the above embodiment is an imaging optical system that forms an image of the light L, the optical system 104 according to the first modified example is a focusing optical system that focuses the light L.

[0075] The light irradiation device 101 includes a light output unit 103, an optical system 104, and a control unit (not shown). For example, the light irradiation device 101 is a scanner provided in a laser scanning microscope. In the light irradiation device 101, the light L output from the light output unit 103 is focused on an object by the optical system 104. Then, the optical system 104 moves a focusing position P50 of the light L on the object. As a result, the object is spot-scanned in the laser scanning microscope to which the light irradiation device 101 is applied.

[0076] The light output unit 103 outputs light L traveling as parallel light to the parallel light path portion P1. Specifically, the light output unit 103 has a light source 103a that outputs the light L traveling as parallel light toward the optical system 104. The light output unit 103 emits laser light generated by the light source 103a. The light L from the light source 103a becomes parallel light when it is emitted from the light source 103a. In this example, the parallel light is laser light output from the light source. As described above, the parallel light traveling through the parallel light path portion P1 may be collimated light collimated by a lens as in the above embodiment, or may be parallel light output from a light source as in the first modified example. The light source 103a may generate CW (Continuous Wave) light or pulsed light to be irradiated onto an object. The light L generated by the light source 103a is coherent light such as laser light. A solid-state laser light source, a semiconductor laser light source, or the like can be used as the light source 103a.

[0077] The optical system 104 has an objective lens 41 and an optical deflection unit 42. The objective lens 41 is a lens (first lens) that collects light L from the optical deflection unit 42 (prism unit 50). The optical system 104 is an optical system having a parallel optical path portion P1 along which the light L travels as parallel light. In the example shown in FIG. 12, the light L from the light source 103a passes through the objective lens 41 and reaches the object. The light L from the light source 103a becomes parallel light between the light source 103a and the objective lens 41 (first lens), and becomes convergent light between the objective lens 41 and the object. The parallel optical path portion P1 is a portion along which the light L travels as parallel light, and is a portion between the light source 103a of the optical output unit 103 and the objective lens 41 (first lens). In the first modified example, the optical axis direction of the parallel optical path portion P1 is a direction parallel to a line (optical axis) passing through the light source 103a (the output portion of the light source 103a for the light L) and the center C41 of the objective lens 41, for example, direction D4.

[0078] In the optical system 104, the light L output to the parallel optical path portion P1 passes through the light deflection unit 42 and enters the objective lens 41. The objective lens 41 focuses the light L from the light deflection unit 42 (prism unit 50) on an object. The light deflection unit 42 deflects the light L output from the light output unit 103, thereby moving the focusing position P50 of the light L on the object.

[0079] The control unit controls the light deflection unit 42 (prism unit 50) via a rotation mechanism (not shown). The control unit controls the rotation mechanism to control the rotation angle of the prism unit 50 (for example, the rotation angle θ1 around the central axis of the first prism 51). In this example, the control unit 8 also controls and processes other elements in the light irradiation device 101.

[0080] In this light irradiation device 101, by changing the rotation angle θ1 around the central axis of the first prism 51, for example, it is possible to shift the focusing position P50 of the light L by the objective lens 41 relative to the optical axis A41 along a direction intersecting the optical axis direction (direction D5 intersecting with direction D4). Furthermore, in the light irradiation device 101, the shift amount of the light L from the optical axis A41 with respect to a change in the rotation angle θ1 of the first prism 51 is smaller than when the light deflection unit 42 deflects the light L from the light output unit 3 by reflecting it, so it is possible to control the focusing position P50 of the light L with higher precision.

[0081] In the optical system 104 according to the first modification, the objective lens 41 collects the light L from the prism portion 50. In this case, in the optical system 104, which is a collecting optical system, it is possible to shift the relative position between the input light and the output light (collecting position) along a direction intersecting the optical axis direction (direction D5 intersecting with direction D4) with a simple configuration. [Second Modification]

[0082] FIG. 13 is a diagram showing a light irradiation device 101 to which an optical system 104 according to a second modification is applied. The light irradiation device 101 is a scanner that scans multiple lines set in a predetermined area on an object. The light irradiation device 101 scans the lines by moving a focusing position P50 of light L along the lines extending in a direction D5. While the light irradiation device 101 of the first modification irradiates the object with linear light L, the light irradiation device 101 of the second modification irradiates the object with planar light (sheet light) LS extending along the direction D5. Specifically, while the light irradiation device 101 moves the focusing position P50 of light L on the object along the direction D5, an image sensor (not shown) captures an image of light LD from the object via an observation-side objective lens 141. This allows the image sensor to capture the light LD from the object while regarding the light L irradiated to the object as planar light LS.

[0083] More specifically, the control unit 8 rotates the first prism 51 through the rotation angle θ1 to move the focusing position P50 of the light L along a line extending in the direction D5. The image capturing element continues to receive the light LD from the object through the observation-side objective lens 141 while the focusing position P50 of the light L moves along a line. As a result, for example, by setting the exposure time of the image capturing element to be longer than the time required for the light irradiation device 101 to scan a line (the time required for the focusing position P50 of the light L to start and finish moving along a line), the image capturing element can capture an image of the light LD generated from the object, regarding the light L irradiated onto the object as planar light LS irradiated over the entire line. [Variations]

[0084] The present invention is not limited to the above-described embodiment and each modified example. For example, in the above-described embodiment and each modified example, the parallel light in the optical system 4, 104 is light collimated by a lens or laser light output from a light source, but is not limited to this. The parallel light may be light that travels with all of its rays parallel to one another.

[0085] Although the prism unit 50 of the optical system 4, 104 includes the first prism 51 and the second prism 52, it may include only the first prism 51. FIG. 14 illustrates an optical system 4 according to a third modification. In the example illustrated in FIG. 14, the control unit 8 rotates the first prism 51 clockwise to move the focusing position P50 of the light L on the imaging surface 5a along the direction D5. In the optical system 4 according to the third modification, when the wavelength width of the light L is sufficiently narrow, such as in the case of a CW laser, the dispersion caused by the first prism is sufficiently small. Furthermore, compared to when the prism unit 50 further includes the second prism 52, the light L shifts to a position farther away from the optical axis A41 of the objective lens 41.

[0086] In the prism unit 50 of the optical system 4, 104, the first prism 51 is rotatable about a central axis extending along the direction D6. However, it is sufficient that at least one of the first prism 51 and the second prism 52 is rotatable about a central axis extending along the direction D6. For example, the second prism 52 may be rotatable about a central axis extending along the direction D6. In this case, by refracting the light L from the sample S at at least one of the third surface 52a and the fourth surface 52b of the second prism 52, the light L from the sample S can be shifted along the direction D5 by the second prism 52. Then, the light L from the sample S is refracted at at least one of the first surface 51a and the second surface 51b of the first prism 51. As a result, dispersion caused by refraction at the second prism 52 can be reduced by refraction at the first prism 51.

[0087] In the prism section 50 of the optical system 4, 104, when the rotation angle θ1 of the first prism 51 about the central axis is a certain angle (for example, 0 degrees), the second surface 51b is located on the side of the second prism 52, the first surface 51a is located on the opposite side from the second prism 52, the third surface 52a is located on the side of the first prism 51, and the fourth surface 52b is located on the opposite side from the first prism 51. The second surface 51b is parallel to the third surface 52a, and the first surface 51a is parallel to the fourth surface 52b, but this is not limiting. For example, when the rotation angle θ1 around the central axis of the first prism 51 is a certain angle, one of the first surface 51a and the second surface 51b may be located on the side of the second prism 52, the other of the first surface 51a and the second surface 51b may be located on the opposite side of the second prism 52, one of the third surface 52a and the fourth surface 52b may be located on the side of the first prism 51, and the other of the third surface 52a and the fourth surface 52b may be located on the opposite side of the first prism 51. Then, one of the first surface 51a and the second surface 51b may be parallel to one of the third surface 52a and the fourth surface 52b, and the other of the first surface 51a and the second surface 51b may be parallel to the other of the third surface 52a and the fourth surface 52b.

[0088] Although the optical system 4 includes the objective lens 41 (second lens), the light deflection unit 42, and the imaging lens 43 (first lens), and the optical system 104 includes the light deflection unit 42 and the objective lens 41, the present invention is not limited to this. The optical systems 4 and 104 may include the light deflection unit 42 and a lens capable of converting the parallel light in the parallel light path portion P1 into convergent light. For example, the optical system 4 may include only the imaging lens 43 (first lens) that collects the light L from the light deflection unit 42 (prism unit 50), or the optical system 4 may include only the light deflection unit 42 and the imaging lens 43 (first lens).

[0089] In the optical system 4, the imaging lens 43 corresponds to the first lens, and in the optical system 104, the objective lens 41 corresponds to the first lens, but this is not limitative. The first lens may be any lens that can collect the light L from the prism portion 50, and may be any lens other than those described above.

[0090] In the optical system 104, the first prism 51 rotates around a central axis extending along the direction D6, but the first prism 51 may be rotatable around multiple central axes. Furthermore, the light irradiation device 101 may be provided with multiple optical systems 104. In these cases, the focusing position P50 of the light L can be moved on a plane extending along the directions D5 and D6.

[0091] In the optical system 4, 104, the light L is focused at the focusing position P50, which is the focal point of the imaging lens 43 or the objective lens 41 (first lens), but is not limited to this. For example, in the optical system 4, 104, the light L may be focused at a predetermined focusing region (focusing spot).

[0092] FIG. 15 is a diagram showing an optical system 4 according to a fourth modification. As shown in FIG. 15, in the optical system 4, the imaging lens 43 may be movable along direction D5 (a direction perpendicular to the optical axis direction of the parallel optical path portion P1) so that light L from the objective lens 41 (light L from the prism portion 50) passes through a center C43 of the imaging lens 43. The image sensor 5 may be movable in direction D5 (a direction along the imaging surface 5a) in accordance with the movement of the imaging lens 43 so that light from the same region of the sample S is incident on the same region on the imaging surface 5a of the image sensor 5. In this case, even if the light L output from the optical system 4 is shifted along direction D5 with respect to the optical axis A41 of the objective lens 41, the light L that enters the prism portion 50 and exits from the prism portion 50 passes through the center C43 of the imaging lens 43, thereby improving the imaging performance.

[0093] In this modification, the imaging lens 43 is movable along a direction perpendicular to the optical axis direction of the parallel optical path portion P1, but this is not limiting. The imaging lens 43 may be movable along a direction intersecting the optical axis direction of the parallel optical path portion P1. Furthermore, the imaging surface 5a is movable along the direction D5, but may be movable in any direction along the imaging surface 5a. For example, the light L from the sample S may reach the imaging surface 5a with the traveling direction of the light L changed by a reflecting surface such as a mirror. In such a case, the imaging surface 5a may be movable in a direction intersecting the traveling direction of the light L from the sample S reaching the imaging surface 5a, for example, in the direction D3 shown in FIG.

[0094] 15, the optical system 4 further includes a movement mechanism 90 that is capable of moving the imaging lens 43 and the imaging surface 5a of the image sensor 5 along direction D5. Based on the shift amount of the light L from the optical axis A41, the control unit 8 controls the position of the imaging lens 43 in direction D5 via the movement mechanism 90 so that the light L from the prism unit 50B passes through the center C43 of the imaging lens 43. The control unit 8 controls the position of the imaging surface 5a in direction D5 so as to cancel out the movement of the focusing position of the light L from the sample S that corresponds to the movement of the imaging lens 43.

[0095] Furthermore, in this modification, the imaging lens 43 is movable along a direction intersecting the optical axis direction of the parallel optical path portion P1, but it is sufficient if at least one of the objective lens 41 and the imaging lens 43 is movable along a direction intersecting the optical axis direction of the parallel optical path portion P1. For example, the objective lens 41 may be movable along a direction intersecting the optical axis direction of the parallel optical path portion P1, or both the objective lens 41 and the imaging lens 43 may be movable along a direction intersecting the optical axis direction of the parallel optical path portion P1.

[0096] 16 is a diagram showing an optical system 4 according to a fifth modified example. In the fifth modified example, the first prism 51 and the second prism 52 are arranged such that, when the rotation angle θ1 of the first prism 51 about the central axis is a certain angle (for example, when the first surface 51a is parallel to the fourth surface 52b and the second surface 51b is parallel to the third surface 52a), the difference between the angle of incidence and the angle of emission of the light L at the first prism 51 is minimized, and the difference between the angle of incidence and the angle of emission of the light L at the second prism 52 is minimized. In other words, the first prism 51 and the second prism 52 are arranged under an incidence condition that minimizes the deviation angles of the first prism 51 and the second prism 52 (the amount of light refraction in the prisms). In this case, it is possible to minimize image distortion caused by transmission through the first prism 51 and the second prism 52. 16, the difference between the incident angle θ11 of light L incident on the first surface 51a and the exit angle θ12 of light L exiting from the second surface 51b is minimum. As an example, the incident angle θ11 and the exit angle θ12 are equal. Furthermore, the difference between the incident angle θ21 of light L incident on the third surface 52a and the exit angle θ22 of light L exiting from the fourth surface 52b is minimum. As an example, the incident angle θ21 and the exit angle θ22 are equal. [Explanation of symbols]

[0097] 1...optical imaging device, 3a, 103a...light source, 4, 104...optical system, 5...imaging element (imaging unit), 8...control unit, 41...objective lens (second lens) (first lens), 42...light deflection unit, 43...imaging lens (first lens), 50...prism unit, 51...first prism, 51a...first surface, 51b...second surface, 52...second prism, 52a...third surface, 52b...fourth surface, 101...light irradiation device, L...light, P1...parallel light path portion, θ1...rotation angle, θ11...incident angle, θ12...exit angle, θ21...incident angle, θ22...exit angle, C43...center, D4...direction (optical axis direction).

Claims

1. An optical system having a parallel optical path portion in which light travels as parallel light, a prism section having a first prism including a first surface and a second surface inclined with respect to the first surface, wherein the light incident from the first surface passes through the first prism and exits from the second surface, wherein the light traveling as the parallel light in the parallel optical path portion is incident on the prism section, and the prism section refracts the light at at least one of the first surface and the second surface; a first lens that condenses the light from the prism portion, The optical system, wherein the first prism is rotatable about a central axis that intersects with the optical axis direction of the parallel optical path portion.

2. 2. The optical system according to claim 1, further comprising a second prism including a third surface and a fourth surface inclined relative to the third surface, wherein the light incident from the third surface passes through the second prism and exits from the fourth surface, and the light is refracted at at least one of the third surface and the fourth surface.

3. 3. The optical system according to claim 2, wherein, when a rotation angle of the first prism about the central axis is a certain angle, one of the first and second surfaces is located on the second prism side, the other of the first and second surfaces is located on the opposite side from the second prism, one of the third and fourth surfaces is located on the first prism side, the other of the third and fourth surfaces is located on the opposite side from the first prism, the one of the first and second surfaces is parallel to the one of the third and fourth surfaces, and the other of the first and second surfaces is parallel to the other of the third and fourth surfaces.

4. 4. The optical system according to claim 3, wherein the first prism and the second prism are arranged such that, when the rotation angle of the first prism about the central axis is the certain angle, a difference between an incident angle and an exit angle of the light at the first prism is minimized, and a difference between an incident angle and an exit angle of the light at the second prism is minimized.

5. a second lens that is an objective lens that outputs the light traveling as the parallel light to the parallel light path portion; 5. The optical system according to claim 1, wherein the first lens is an imaging lens that forms an image from the light from the prism portion.

6. 6. The optical system according to claim 5, wherein at least one of the objective lens and the imaging lens is movable along a direction intersecting the optical axis direction of the parallel light path portion so that the light from the prism portion passes through the center of the imaging lens.

7. The optical system according to claim 5 ; an imaging unit that captures an image of light from the optical system; a control unit that controls a rotation angle of the first prism about the central axis.

8. 5. The optical system according to claim 1, wherein the first lens is an objective lens that collects the light from the prism portion.

9. an optical system according to claim 8; a light source that outputs the light traveling as parallel light toward the optical system; a control unit that controls a rotation angle of the first prism about the central axis.

Images