Imaging device and optical element

Abstract

To provide an imaging device capable of imaging the wavefront and polarization of light in parallel.SOLUTION: The imaging device includes an optical element including a plurality of lenses arranged one-dimensionally or two-dimensionally, an imaging part for imaging the light transmitted through the optical element, and a processing part for outputting each of the polarization information and wavefront information of incident light to the optical element on the basis of a captured image by the imaging part. The optical element has polarization characteristics in which a main axis azimuth is periodically different according to a position along the outer periphery of the lens, in the outer peripheral part of each of the plurality of lenses.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to imaging devices and optical elements. [Background technology]

[0002] Conventionally, wavefront sensors that detect the wavefront of light and polarization imaging devices that use the polarization of light are known. These are used in applications such as cameras mounted on automobiles and smartphones, inspection tools for optical components and optical films, and medical devices in ophthalmology for evaluating refractive errors after cataract surgery and for definitively diagnosing amyloidosis, and the range of applications is expected to expand further.

[0003] As a wavefront sensor, one that calculates a wavefront based on the positions of a part or all of the light transmitted through each of a plurality of lenslets has been disclosed (see, for example, Patent Document 1). Also, an imaging device has been disclosed that includes a measuring means that measures the aberration of light having a predetermined polarization component and a predetermined wavelength among the return light from an object to be inspected that has been irradiated with measurement light (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 9-15057 [Patent Document 2] JP 2014-108214 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, the wavefront sensor of Patent Document 1 and the imaging device of Patent Document 2 do not disclose imaging of the wavefront and polarization of light in parallel.

[0006] The present disclosure aims to provide an imaging device and an optical element capable of imaging the wavefront and polarization of light in parallel. [Means for solving the problem]

[0007] An imaging device according to an embodiment of the present disclosure includes an optical element including a plurality of lenses aligned one-dimensionally or two-dimensionally, an imaging unit that images light transmitted through the optical element, and a processing unit that outputs, based on an image captured by the imaging unit, polarization information and wavefront information of light incident on the optical element, wherein the optical element has polarization characteristics in which the principal axis orientations differ periodically depending on the position along the outer periphery of each of the plurality of lenses.

[0008] An optical element according to an embodiment of the present disclosure includes a plurality of lenses aligned one-dimensionally or two-dimensionally, and at the outer periphery of each of the plurality of lenses, the lens has polarization characteristics in which the principal axis orientations vary periodically depending on the position along the outer periphery of the lens. Effect of the Invention

[0009] According to the present disclosure, it is possible to provide an imaging device and an optical element capable of imaging the wavefront and polarization of light in parallel. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic diagram showing a configuration of an imaging device according to a first embodiment. [Diagram 2] 2A to 2C are diagrams illustrating a lens outer periphery of the optical element according to the first embodiment. [Diagram 3] 2 is a block diagram showing a hardware configuration of a processing unit according to the first embodiment. FIG. [Figure 4] 3 is a block diagram showing the functional configuration of a processing unit according to the first embodiment. FIG. [Diagram 5] 4A to 4C are diagrams illustrating the relationship between a wavefront, polarization, and a captured image according to the embodiment. [Figure 6] FIG. 6 is a diagram showing an image of the periphery of the lens in FIG. 5. [Figure 7] 5A to 5C are diagrams illustrating a method for acquiring polarization information according to an embodiment. [Figure 8] FIG. 2 is a diagram showing a captured image according to the first embodiment. [Figure 9] FIG. 9 is a diagram showing an enlarged image of region IX in FIG. 8. [Figure 10] FIG. 10 is a diagram showing the luminance of pixels included in the outer circle in the image of FIG. [Figure 11] 1A and 1B are diagrams illustrating imaging results of a wavefront according to an embodiment. [Figure 12] FIG. 13 is a diagram showing an imaging result of polarized light according to an embodiment. [Figure 13] 5A to 5C are schematic diagrams illustrating a method for manufacturing an optical element according to an embodiment. [Figure 14] FIG. 1 is a diagram showing a lens formed by laser processing. [Figure 15] FIG. 11 is a schematic diagram showing a configuration of an imaging device according to a second embodiment. [Figure 16] FIG. 11 is a schematic diagram showing the functional configuration of a processing unit according to a second embodiment. [Figure 17] FIG. 2 is a diagram showing an image of the periphery of a lens in a first captured image. [Figure 18] FIG. 13 is a diagram showing an image of the periphery of the lens in the second captured image. [Figure 19] FIG. 4 is a diagram showing an added image of a first captured image and a second captured image. [Figure 20] FIG. 20 is a diagram showing the luminance of pixels included in the outer circle in the image of FIG. 19. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] An imaging device and an optical element according to an embodiment of the present disclosure will be described in detail with reference to the drawings. However, the following embodiments are merely examples of imaging devices and optical elements for realizing the technical ideas of the present embodiment, and are not limited to the following.

[0012] Unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described in the embodiments are merely illustrative examples and are not intended to limit the scope of the present disclosure. The sizes, positional relationships, etc. of the components shown in each drawing may be exaggerated to clarify the explanation. In the following explanation, the same names and symbols indicate the same or similar components, and detailed explanations will be omitted as appropriate.

[0013] In the drawings shown below, a Cartesian coordinate system having an X axis, a Y axis, and a Z axis may be used as a directional expression. The direction along the X axis is called the X direction, the direction along the Y axis is called the Y direction, and the direction along the Z axis is called the Z direction. In addition, the side where the arrow points in the X direction is called the +X side, and the opposite side of the +X side is called the -X side. In the Y direction, the side where the arrow points is called the +Y side, and the opposite side of the +Y side is called the -Y side. In the Z direction, the side where the arrow points is called the +Z side, and the opposite side of the +Z side is called the -Z side. The optical elements included in the imaging device according to the embodiment are aligned along the X direction and the Y direction. In addition, in the terminology used in the specification, planar view refers to viewing an object from the +Z direction. However, these directional expressions do not limit the directions of the embodiments of the present disclosure.

[0014] [First embodiment] <Configuration Example of Imaging Device 100> The configuration of the imaging device according to the first embodiment will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a schematic diagram illustrating an example of the configuration of the imaging device 100 according to the first embodiment. Fig. 2 is a diagram illustrating a lens outer periphery 11 of an optical element 1 included in the imaging device 100.

[0015] The imaging device 100 includes an optical element 1, an imaging unit 2, and a processing unit 3. In the example shown in Fig. 1, the imaging device 100 includes a housing 4, a polarizing member 5, a light source 6, and a collimating lens 7. Fig. 1 shows a schematic cross section of the imaging device 100 including the optical element 1, the imaging unit 2, the housing 4, and the polarizing member 5.

[0016] The imaging device 100 outputs each of wavefront information and polarization information of the incident light 62 to the optical element 1 from the processing unit 3 based on an image captured by the imaging unit 2. The wavefront information refers to information related to the wavefront of the light. The polarization information refers to information related to the polarization of the light. The wavefront information and the polarization information are each imaged information. In this embodiment, the imaging device 100 is capable of imaging the wavefront and polarization of the incident light 62 in parallel.

[0017] The optical element 1 is disposed on the imaging surface 20 (+Z side) of the imaging section 2. The optical element 1 may be disposed in contact with the imaging surface 20, or may be disposed at a position separated from the imaging surface 20 on the +Z side.

[0018] The optical element 1 includes a plurality of lenses 10 aligned two-dimensionally. In the example shown in FIG. 1, five lenses 10 are aligned along each of the X and Y directions. The optical element 1 includes a plurality of lenses 10 on a surface opposite to the side on which the imaging surface 20 is located, and the surface on the side on which the imaging surface 20 is located is flat. That is, the optical element 1 is, for example, a plano-convex lens array having a convex shape in which each of the plurality of lenses 10 protrudes on the side opposite to the side on which the imaging surface 20 is located. The plurality of lenses 10 in the optical element 1 may be aligned one-dimensionally. In addition, in the optical element 1, the number of the plurality of lenses 10, the interval between the plurality of lenses 10, the diameter, shape, and the like of each of the plurality of lenses 10 can be appropriately selected. The optical element 1 may be configured to include, for example, a resin material.

[0019] 2, the lens outer periphery 11 indicated by diagonal hatching is a circular annular portion along the outer periphery of the lens 10 in the optical element 1 in a plan view. Since the lens outer periphery 11 is a portion outside the outer edge of the lens 10 in the optical element 1, each of the surface of the lens outer periphery 11 facing the imaging surface 20 and the surface opposite the imaging surface 20 is substantially flat. However, the lens outer periphery 11 may include the outer edge of the lens 10. The lens outer periphery 11 may be an elliptical annular portion in plan view that matches the shape of the lens 10.

[0020] The optical element 1 has polarization characteristics in which the principal axis orientations periodically vary depending on the position along the periphery of the lens 10 in the lens outer periphery portion 11 of each of the multiple lenses 10. In FIG. 2, the first position 11-1, the second position 11-2, the third position 11-3, and the fourth position 11-4 each correspond to an example of a position along the periphery of the lens 10. The first position 11-1 is a position in the 0 o'clock direction (12 o'clock direction) on the periphery of the lens 10 in a plan view. The second position 11-2 is a position in the 3 o'clock direction on the periphery of the lens 10 in a plan view. The third position 11-3 is a position in the 6 o'clock direction on the periphery of the lens 10 in a plan view. The fourth position 11-4 is a position in the 9 o'clock direction on the periphery of the lens 10 in a plan view.

[0021] The principal axis orientations at the first position 11-1, the second position 11-2, the third position 11-3, and the fourth position 11-4 may be periodically different. For example, when the principal axis orientations are observed in the order of the second position 11-2, the third position 11-3, and the first position 11-1 in a clockwise direction starting from the first position 11-1, the principal axis orientations may be different from each other, and the principal axis orientations may change so as to become the same again at the first position 11-1.

[0022] For example, the principal axis orientation may vary sinusoidally depending on the position along the outer periphery of the lens 10. The wave number of the periodic variation when the length of the lens outer periphery 11 along the outer periphery of the lens 10 is taken as a unit length can be appropriately selected. In a plan view, the width of the lens outer periphery 11 in the radial direction is arbitrary.

[0023] The periodic change in the principal axis orientation in the lens outer circumferential portion 11 may be an approximately periodic change. "Almost periodic" means that the change in each period does not have to be constant, and the amplitude and phase of the change in each period may each include a shift. For example, "almost periodic" means that the amplitude of the change may shift by about ±30% and the phase of the change may shift by about ±30% of the period depending on image noise, etc.

[0024] The pixel luminance corresponding to the position along the periphery of the lens 10 in the captured image Im changes almost periodically in accordance with the change in the principal axis direction of the incident light 62 passing through the lens peripheral portion 11 in accordance with the position along the periphery of the lens 10. In this embodiment, based on this change in pixel luminance, the principal axis direction of the incident light 62 can be detected, and the polarization state of the incident light 62 can be detected.

[0025] From another point of view, in this embodiment, the principal axis direction of the incident light 62 passing through the lens outer peripheral portion 11 changes almost periodically depending on the position along the outer periphery of the lens 10, so that it is possible to obtain an effect equivalent to the rotation of the analyzer in the rotating analyzer method, for example. Here, the rotating analyzer method refers to a method in which the light intensity of the light passing through the analyzer is detected while rotating the analyzer, and the polarization state of the light incident on the analyzer is detected from the change in light intensity accompanying the rotation of the analyzer. In this embodiment, the light intensity is not detected while rotating the analyzer as in the rotating analyzer method, but the change in pixel brightness corresponding to the change in the principal axis direction of the incident light 62 is obtained from one captured image Im, so that it is possible to image polarization from one captured image Im.

[0026] The inner regions of the lenses 10 may have polarization characteristics in which the principal axis orientations are randomly different in plan view. Randomly varying the principal axis orientations of the inner regions of the lenses 10 makes it easier to distinguish between the inner regions of the lenses 10 and the lens outer peripheral portion 11, and makes it easier to detect changes in the principal axis orientations of the incident light 62 according to the position along the outer periphery of the lenses 10. As a result, in this embodiment, the accuracy of polarized light imaging by the imaging device 100 can be improved.

[0027] In the lens outer periphery 11 of each of the lenses 10, the absolute value of the difference between the birefringence phase differences at each of the positions along the periphery of the lens 10 may be 10 degrees or less. For example, the birefringence phase differences at each of the positions along the periphery of the lens 10 may be approximately equal to each other. For example, when the difference between the birefringence phase differences at each of the positions along the periphery of the lens 10 becomes large, the influence of the birefringence phase difference included in the change in pixel luminance at each of the positions along the periphery of the lens 10 becomes large in the captured image Im. As a result, the accuracy of imaging the polarized light by the imaging device 100 may be reduced. In this embodiment, the absolute value of the difference between the birefringence phase differences at each of the positions along the periphery of the lens 10 is set to 10 degrees or less, thereby reducing the influence of the birefringence phase difference included in the change in pixel luminance at each of the positions along the periphery of the lens 10. This makes it possible to improve the accuracy of imaging the polarized light by the imaging device 100.

[0028] The shape of the lens 10 may be either a circle or an ellipse in a plan view. By making the shape of the lens 10 either a circle or an ellipse in a plan view, the principal axis direction can be changed continuously according to the position along the outer periphery of the lens 10, compared to, for example, a case in which the shape of the lens 10 in a plan view is rectangular. This can increase the accuracy of polarized light imaging by the imaging device 100.

[0029] In this embodiment, the imaging resolution can be increased (the number of pixels can be increased) by increasing the number of lenses 10 included in the optical element 1. Also, the imaging spatial resolution can be increased by decreasing the area of ​​the lenses 10 in a top view.

[0030] In FIG. 1, the imaging unit 2 captures an image of light transmitted through the optical element 1. The imaging unit 2 includes an imaging element in which pixels are two-dimensionally arranged. The imaging element may be a charge coupled device (CCD) or a complementary metal oxide semiconductor (CMOS). The imaging unit 2 outputs a captured image Im to a processing unit 3. The imaging unit 2 is preferably disposed such that an imaging surface 20 is located at a focal position of a lens 10 in the optical element 1. The focal position of the lens 10 corresponds to a position (e.g., a beam waist position) where the light transmitted through the lens 10 is most focused when incident light 62, which is a plane wave, is incident on the lens 10.

[0031] The housing 4 is a box-shaped member including an opening penetrating in the Z direction and capable of arranging the optical element 1 inside. The optical element 1 arranged inside the housing 4 can transmit the incident light 62 from the outside of the housing 4 toward the imaging surface 20. The housing 4 is preferably made of a resin material, a metal material, or the like having a low transmittance for the incident light 62 from the imaging device 100. The transmittance here is preferably 30% or less for the incident light 62. By providing the housing 4 to the imaging device 100, it becomes difficult for external light to be incident on the optical element 1, and the imaging accuracy of the polarization and wavefront of the incident light 62 can be improved. However, the imaging device 100 does not necessarily have to include the housing 4.

[0032] The polarizing member 5 is disposed between the optical element 1 and the imaging surface 20. The polarizing member 5 is an optical element that transmits light having a desired polarization state among the light transmitted through the optical element 1. The polarizing member 5 may be a linear polarizing plate or a linear polarizing film. The polarizing member 5 is disposed, for example, by being adhered to the surface of the housing 4 on the imaging surface 20 side by an adhesive member or the like. However, the polarizing member 5 may be adhered to the surface of the optical element 1 on the imaging surface 20 side by an adhesive member or the like. By providing the polarizing member 5, the imaging device 100 can increase the SNR (signal-noise ratio) of the change in pixel luminance according to the position along the outer periphery of the lens 10. This allows the polarization state of the light transmitted through the optical element 1 to be detected with high accuracy, and the imaging accuracy of the polarized light can be increased. However, the imaging device 100 does not necessarily have to include the polarizing member 5.

[0033] As an example, the light source 6 emits light 60 that is the source of incident light 62 on the optical element 1 that is the object of imaging by the imaging device 100. The light source 6 can be appropriately selected from various light sources such as a semiconductor laser, a solid-state laser, a light-emitting diode, etc. depending on the application. From the viewpoint of miniaturizing the imaging device 100, a small light source such as a semiconductor laser or a light-emitting diode is preferable. From the viewpoint of increasing the accuracy of polarization imaging, it is preferable that the light source 6 emits light in an almost uniform polarization state, for example, it is preferable that the light source 6 emits almost linearly polarized light. "Almost linearly polarized" means that the extinction ratio is preferably 1:100 or more.

[0034] The imaging device 100 may be configured such that unpolarized light is emitted by the light source 6, and approximately linearly polarized light is extracted by a polarizing plate or the like arranged in the optical path between the light source 6 and the optical element, and the light is incident on the optical element 1. In addition, the imaging device 100 is not necessarily required to include the light source 6, since it can image the polarization and wavefront of various types of incident light 62 on the optical element 1, not limited to light from the light source 6.

[0035] The collimating lens 7 is a lens that converts the light 60 emitted from the light source 6 into an approximately plane wave (approximately parallel light). The approximately plane wave means a plane wave or a spherical wave close to a plane wave. The optical axis 70 is the optical axis of the collimating lens 7. The collimating lens 7 can be various lenses such as a single lens and a lens assembly. From the viewpoint of reducing the influence of the polarization characteristics on the light passing through the collimating lens 7, the collimating lens 7 is preferably made of a glass material having a high light transmittance for the light to be imaged. The light transmittance here is preferably 80% or more, for example. The imaging device 100 can easily obtain wavefront information of the light 62 incident on the optical element 1 by converting the light 60 into an approximately plane wave by the collimating lens 7. However, the imaging device 100 does not necessarily have to include the collimating lens 7.

[0036] 1, a phase surface 61a represents an equiphase surface of light 60 emitted from a light source 6. A phase point 61b represents a point on the phase surface 61a. The spherical wave emitted from the light source 6 is converted into a substantially plane wave by the collimator lens 7 and propagates toward the optical element 1. The phase surface 61a becomes substantially flat.

[0037] 1, when a sample Q having optical transparency to light to be imaged is placed in the optical path between the collimator lens 7 and the optical element 1, the wavefront state and polarization state of the incident light 62 are changed by the sample Q. A phase surface 61a' represents a phase surface changed from a planar state by the sample Q. Each of phase points 61b-1 and 61b-2 represents a phase point whose position has changed in response to the change from phase surface 61a to phase surface 61a'.

[0038] For example, the incident light 62 to the lens 10-1 includes a phase surface 61a in a substantially planar state because the wavefront state and the polarization state are not changed by the sample Q. When such incident light 62 passes through the lens 10-1, a focused image 23-1 is obtained on the imaging surface 20 at a position that corresponds to approximately the central axis 10-1c of the lens 10-1. On the other hand, the incident light 62 to the lens 10-2 includes a phase surface 61a' that is changed from the substantially planar state because the wavefront state and the polarization state are changed by the sample Q. When such incident light 62 passes through the lens 10-2, a focused image 23-2 is obtained on the imaging surface 20 at a position that is shifted from a position that corresponds to approximately the central axis 10-2c of the lens 10-2. For example, in the XY plane that is substantially parallel to the imaging surface 20, a focused image 23-2 is obtained at a position that is shifted in the shift direction φ by a shift amount d from the central axis 10-2c of the lens 10-2. The imaging device 100 can image the wavefront of the incident light 62 by imaging the wavefront tilt vector at each position of the multiple lenses 10 included in the optical element 1 based on the amount of deviation d and the direction of deviation φ.

[0039] As described above, the imaging device 100 can image the wavefront of the incident light 62, which is changed by the sample Q, for example, based on the positions of the focused images 23-1, 23-2, etc. Also, as described above, based on the pixel brightness of the lens outer periphery 11 obtained for each of the multiple lenses 10, the imaging device 100 can image the polarization of the incident light 62, which is changed by the sample Q, for example. In this embodiment, since the imaging of the wavefront and the imaging of the polarization can be performed using the same captured image Im, the imaging device 100 can image the wavefront and the polarization of the light in parallel. Also, since the imaging device 100 can image the wavefront and the polarization of the light in parallel using one captured image Im, the imaging device 100 can image the wavefront and the polarization of the light dynamically (i.e., as a moving image).

[0040] <Configuration example of processing unit 3> (Hardware configuration example) 3 is a block diagram showing an example of a hardware configuration of the processing unit 3. The processing unit 3 is constructed by, for example, a computer. The processing unit 3 has a CPU (Central Processing Unit) 301, a ROM (Read Only Memory) 302, a RAM (Random Access Memory) 303, an HDD / SSD 304, and a connection I / F (Interface) 305. These are connected to each other via a system bus A so as to be able to communicate with each other.

[0041] The CPU 301 executes control processing including various types of arithmetic processing. The ROM 302 stores programs used to drive the CPU 301, such as an IPL (Initial Program Loader). The RAM 303 is used as a work area for the CPU 301. The HDD / SSD 304 is a non-volatile memory that stores programs, captured images acquired by the imaging unit 2, information regarding the positions of multiple pixels along the outer periphery of the lens 10 (described later), and the like. The connection I / F 305 is an interface for connecting the processing unit 3 to various types of external devices. The external devices here include the imaging unit 2, etc.

[0042] (Example of functional configuration) Fig. 4 is a block diagram showing an example of a functional configuration of the processing unit 3. The processing unit 3 has a first acquisition unit 31, a second acquisition unit 32, and an output unit 33. Each function of the first acquisition unit 31 and the second acquisition unit 32 can be realized by a processor such as the CPU 301 in Fig. 3 executing a process defined in a program stored in a non-volatile memory such as the ROM 302. The function of the output unit 33 can be realized by a connection I / F 305 or the like. Note that some of the above functions of the processing unit 3 may be realized by an external device such as a PC (Personal Computer), or may be realized by distributed processing between the processing unit 3 and the external device.

[0043] The first acquisition unit 31 acquires polarization information based on the luminance of each of a plurality of pixels along the periphery of the lens 10 in the captured image Im. For example, the first acquisition unit 31 acquires the captured image Im from the imaging unit 2 by controlling communication with the imaging unit 2. The first acquisition unit 31 extracts information on the luminance of each of a plurality of pixels along the periphery of the lens from the lens periphery portion 11 in the captured image Im by image processing. The first acquisition unit 31 can acquire polarization information of the incident light 62 by calculation based on the luminance of the extracted plurality of pixels. The first acquisition unit 31 can acquire polarization information of the incident light 62 for each image (lens peripheral image described later) corresponding to a plurality of lenses in the captured image Im.

[0044] The second acquisition unit 32 acquires wavefront information based on the center position of the lens 10 and the position of the collected image of the incident light 62 by the lens 10 in the captured image Im. For example, the second acquisition unit 32 can acquire wavefront information based on the amount of shift d and the direction of shift φ of the position of the collected image of the incident light 62 by the lens 10 relative to the center position of the lens 10.

[0045] Specifically, the second acquisition unit 32 inputs, for example, the captured image Im acquired by the first acquisition unit 31 from the first acquisition unit 31. However, the second acquisition unit 32 may acquire the captured image Im from the imaging unit 2 in parallel with the first acquisition unit 31 by controlling communication with the imaging unit 2. The second acquisition unit 32 acquires information on the position of the collected image of the incident light 62 by the lens 10 in the captured image Im by image processing. The second acquisition unit 32 also acquires information on the center position of the lens 10 in the captured image Im by image processing. The second acquisition unit 32 can acquire wavefront information of the incident light 62 by calculation based on the information on the collected image and the information on the center position. The second acquisition unit 32 can acquire wavefront information of the incident light 62 for each image corresponding to a plurality of lenses in the captured image Im.

[0046] The output unit 33 controls communication with an external device or the like, and outputs, in parallel to the external device, the polarization information of the incident light 62 obtained by the first acquisition unit 31 and the wavefront information of the incident light 62 obtained by the second acquisition unit 32. Examples of the external device here include a PC, a server, a display device, a storage device, and the like.

[0047] <Example of how to obtain polarization and wavefront information> An example of a method for acquiring polarization information and wavefront information by the imaging device 100 will be described with reference to Figs. 5 to 7. Fig. 5 is a diagram showing an example of the relationship between polarization and a wavefront and a captured image. Fig. 6 is a first diagram for explaining an example of a method for acquiring polarization information. Fig. 7 is a second diagram for explaining an example of a method for acquiring polarization information.

[0048] In Fig. 5, the captured image Im is an image captured by the imaging unit 2 shown in Fig. 1. The captured image Im includes a plurality of lens peripheral images 21 obtained by capturing images by the respective lenses 10 in the optical element 1. The overall outer shape of the captured image Im shown in Fig. 5 is circular. However, the overall outer shape of the captured image Im may also be rectangular.

[0049] Each of the multiple lens peripheral images 21 includes a light-collected image 23 by the lens 10. A center position 22 typically indicates the center position of the lens 10 in the captured image Im. The center position 22 corresponds to the position where the central axis of the lens 10, such as the central axis 10-1c and the central axis 10-2c in FIG. 1, intersects with the imaging surface 20 of the imaging unit 2.

[0050] FIG. 6 is an enlarged view of one of the lens peripheral images 21 in FIG. 5. An arrow 26 connects the central position 22 and the center of gravity of the focused image 23. The arrow 26 represents a wavefront tilt vector. The length of the arrow 26 corresponds to the shift amount d. The direction of the arrow 26 corresponds to the shift direction φ. The position where the arrow 26 connects to the focused image 23 is not limited to the center of gravity of the focused image 23, and may be a position other than the center of gravity within the focused image 23. The imaging device 100 detects the shift amount d and the shift direction φ from the positional relationship between the central position 22 and the focused image 23, and obtains the wavefront tilt vector as wavefront information of the incident light 62.

[0051] The lens outer edge 24 is a portion corresponding to the outer edge of the lens 10 in the lens peripheral image 21. The outer peripheral circle 25 is an annular region included in a portion corresponding to the lens outer peripheral part 11 of the lens 10 in the lens peripheral image 21. The width of the outer peripheral circle 25 in the radial direction corresponds to, for example, one pixel of the imaging unit 2. Note that the circles representing the lens outer edge 24 and the outer peripheral circle 25 in FIG. 6 are shown diagrammatically for the purpose of explanation, and are not actually formed on the optical element 1. This point is the same for the circles representing the lens outer edge 24 and the outer peripheral circle 25 hereinafter.

[0052] Fig. 7 shows the brightness of multiple pixels included in the outer circumference circle 25 in Fig. 6 along the outer circumference circle 25. In Fig. 7, the horizontal axis represents the angle θ along the outer circumference circle 25, and the vertical axis "Intensity" represents the brightness of the pixels. For example, the angle θ along the outer circumference circle 25 corresponds to 0 degrees at the 0 o'clock direction (12 o'clock direction) of the clock on the outer circumference circle 25 shown in Fig. 6, 90 degrees at the 3 o'clock direction, 180 degrees at the 6 o'clock direction, and 270 degrees at the 9 o'clock direction.

[0053] As shown in Fig. 7, the luminance of the pixels included in the outer circle 25 changes almost periodically and almost sinusoidally. S0 to S3 in Fig. 7 are components included in the Stokes parameter S expressed by the following equation (1). The Stokes parameter S0 represents the intensity, the Stokes parameter S1 represents the difference between the horizontal and vertical components of linearly polarized light, the Stokes parameter S2 represents the difference between the 45-degree linearly polarized light components, and the Stokes parameter S3 represents the difference between right-handed and left-handed circularly polarized light.

number

[0054] The imaging device 100 detects the Stokes parameter S of the incident light 62 from the change in pixel brightness on the outer circumference circle 25, and can obtain, for example, the ellipticity and the major axis direction of the ellipse of the elliptically polarized light of the incident light 62 as polarization information of the incident light 62. This elliptically polarized light includes linearly polarized light (ellipticity 0) and circularly polarized light (ellipticity 1).

[0055] <Examples of Polarized Light and Wavefront Imaging Results by Imaging Device 100> An example of the imaging results of polarization and wavefront by the imaging device 100 will be described with reference to Figs. 8 to 12. Fig. 8 is a diagram showing an image Im captured by the imaging section 2. Fig. 9 is a diagram showing an enlarged image of region IX in Fig. 8. That is, Fig. 9 shows one of a plurality of lens peripheral images 21 in the captured image Im in Fig. 8. Fig. 10 is a diagram showing the luminance of pixels included in the outer circumferential circle in the image in Fig. 9.

[0056] As shown in Fig. 8, the captured image Im includes a plurality of lens peripheral images 21 corresponding to a plurality of lenses 10 in the optical element 1. As shown in Fig. 9, the lens peripheral image 21 includes a focused image 23 by the lens 10, a lens outer edge 24, and a peripheral circle 25. The central position 22 is detected from the position of the center or center of gravity of the lens outer edge 24. The imaging device 100 can acquire wavefront information from the amount of deviation d and the direction of deviation φ (see Fig. 6) of the position of the focused image 23 from the central position 22.

[0057] 10, the luminance of the pixels included in the outer circle 25 varies substantially sinusoidally, although image noise is included. The imaging device 100 can detect the Stokes parameter S from the luminance of the pixels included in the outer circle 25 and obtain polarization information.

[0058] In this specification, image noise refers to the difference component of the luminance of neighboring pixels included in an image. In the example of FIG. 10, the luminance of the neighboring pixels corresponds to "Intensity" for each adjacent "angle θ" on the horizontal axis. This difference component can be expressed as the average value, maximum value, minimum value, or standard deviation of the luminance difference of the neighboring pixels in the image. The larger the difference component of the luminance of the neighboring pixels, the larger the image noise. In the example of FIG. 10, the difference component of the luminance of the neighboring pixels is larger than that of FIG. 7, so the image noise is large.

[0059] 11 is a diagram showing an example of a wavefront imaging result by the imaging device 100. The wavefront information Wf includes multiple arrows 26 obtained for each of the multiple lenses 10 in the optical element 1. As described above, the arrows 26 represent wavefront tilt vectors. The imaging device 100 can image the wavefront of the incident light 62 by visualizing the wavefront tilt vectors at each position of the multiple lenses 10.

[0060] 12 is a diagram showing an example of the imaging result of polarization by the imaging device 100. The polarization information Po includes a plurality of ellipses 27 obtained for each position of the plurality of lenses 10 in the optical element 1. As described above, the ellipses 27 represent the elliptically polarized light of the incident light 62. The imaging device 100 can image the polarization of the incident light 62 by visualizing the elliptically polarized light for each position of the plurality of lenses 10.

[0061] <Example of how to manufacture optical element 1> 13 and 14 are diagrams illustrating a method for producing the optical element 1. Fig. 13 is a schematic diagram showing an example of a method for producing the optical element 1.

[0062] For example, a laser processing method can be used to manufacture the optical element 1. In FIG. 13, a laser processing apparatus 200 has a laser light source 81, an objective lens 82, a duct 83, and a translation stage 84.

[0063] The laser light source 81 is a light source that emits a pulsed laser beam. The laser light source 81 can be appropriately selected from those capable of emitting pulsed laser beams having various pulse widths from femtoseconds to milliseconds. The objective lens 82 focuses the pulsed laser beam 810 emitted from the laser light source 81 onto the surface of the substrate 1' on which the optical element 1 is formed.

[0064] The duct 83 is a ventilation pipe for collecting gas, tar, and the like generated by the laser processing.

[0065] The translation stage 84 has a table 841 and a drive unit 842. The base 1' is placed on the table 841 of the translation stage 84. The translation stage 84 translates the base 1' placed on the table 841 in two axial directions by driving the table 841 with the drive unit 842 configured with a motor or the like. When manufacturing an optical element 1 in which lenses 10 are aligned one-dimensionally, the translation stage 84 translates the base 1' in one axial direction.

[0066] The laser processing device 200 focuses and irradiates a pulsed laser beam 810 from a laser light source 81 onto the surface of a base 1'. The portion of the base 1' irradiated with the pulsed laser beam 810 melts due to heat, and swells so that the surface protrudes toward the side where the laser light source 81 is located. This bulge forms a lens.

[0067] The laser processing apparatus 200 can produce an optical element 1 by irradiating a plurality of predetermined positions on the base 1' with pulsed laser light 810 while translating the base 1' using the translation stage 84, and forming lenses 10 at a plurality of positions on the base 1'.

[0068] Fig. 14 is a diagram showing an example of a lens 10 formed by laser processing. Fig. 14 shows a lens 10 formed on a base 1'. In order to form the lens 10 by expanding the surface of the base 1' and to form a lens peripheral portion 11 having polarization characteristics in which the principal axis orientations periodically differ depending on the position along the circumference of the lens 10, it is preferable to use an acrylic resin colored sky blue or the like as a material constituting the optical element 1.

[0069] Since the optical element 1 can be manufactured by performing laser processing on the base material 1' containing a resin or the like, the optical element 1 can be manufactured simply and at low cost. As a result, the imaging device 100 can be manufactured simply and at low cost.

[0070] [Second embodiment] Next, a description will be given of an imaging device according to a second embodiment. Note that the same names and symbols as those in the already described embodiments indicate the same or similar members or components, and detailed descriptions will be omitted as appropriate.

[0071] This embodiment differs from the first embodiment in that it has a determination unit that determines the positions of multiple pixels along the outer periphery of the lens 10 in the captured image Im based on a first captured image obtained when the incident light 62 is left-handed circularly polarized light and a second captured image obtained when the incident light 62 is right-handed circularly polarized light. The first acquisition unit 31 acquires polarization information based on the luminance of each of the multiple pixels whose positions have been determined by the determination unit. The second acquisition unit 32 acquires wavefront information based on the center position 22 of the lens 10 and the position of the focused image 23, which are obtained from the multiple pixels whose positions have been determined by the determination unit.

[0072] In this embodiment, the positions of a plurality of pixels along the periphery of the lens 10 are determined from the lens peripheral image 21 in which image noise has been reduced by using the first captured image and the second captured image. For example, in this embodiment, as a preliminary preparation for imaging, left-handed circularly polarized light is made incident on the optical element 1 to obtain a first captured image, and then right-handed circularly polarized light is made incident on the optical element 1 to obtain a second captured image. Using the acquired first captured image and second captured image, the positions of a plurality of pixels along the periphery of the lens 10 are determined in advance. Then, imaging is performed using the plurality of pixels whose positions have been determined in advance. This allows the positions of a plurality of pixels to be determined with high accuracy compared to a case in which the positions of a plurality of pixels are determined from a lens peripheral image with large image noise.

[0073] For example, if the positions of multiple pixels along the outer periphery of the lens 10 are determined each time imaging is performed, the positions of the multiple pixels may vary from imaging to imaging due to the influence of image noise, and the imaging accuracy may decrease. In this embodiment, imaging is performed using multiple pixels whose positions have been determined in advance, thereby preventing the positions of the multiple pixels from varying from imaging to imaging, and improving the imaging accuracy. In addition, in this embodiment, the wavefront and polarization of light can be imaged in parallel using one captured image Im, so that the wavefront and polarization of light can be dynamically imaged.

[0074] In this embodiment, each time imaging is performed by the imaging device 100a, a first captured image and a second captured image are acquired, and either one of image averaging and image addition of the first captured image and the second captured image is performed to obtain an image, and imaging of the wavefront and polarization may be performed using the image obtained. By using the first captured image and the second captured image, imaging can be performed from an image with reduced image noise, and therefore imaging can be performed with high accuracy.

[0075] <Configuration Example of Imaging Device 100a> 15 is a schematic diagram showing an example of the configuration of an imaging device 100a according to this embodiment. The imaging device 100a includes a quarter-wave plate 8, a variable mechanism 9, and a processing unit 3a.

[0076] The quarter-wave plate 8 is disposed on the side of the optical element 1 on which the incident light 62 is incident. In the example shown in Fig. 15, the quarter-wave plate 8 is disposed between the collimator lens 7 and the optical element 1. The quarter-wave plate 8 is an optical element that converts the incident light 62 to the optical element 1 into circularly polarized light.

[0077] The variable mechanism 9 varies the orientation of the optical axis of the quarter-wave plate 8 around an axis along the normal direction of the quarter-wave plate 8 so that the optical axis of the quarter-wave plate 8 can be set to either +45 degrees or -45 degrees with respect to the polarization axis of linearly polarized light incident on the quarter-wave plate 8. The optical axis of the quarter-wave plate 8 exists in a plane (the XY plane in FIG. 15 ) approximately perpendicular to the normal to the quarter-wave plate 8. The variable mechanism 9 is configured to include a motor, gears, etc.

[0078] 15, an optical axis 70 of the collimator lens 7 corresponds to an example of an axis along the normal direction of the quarter-wave plate 8. The variable mechanism 9 can rotate the quarter-wave plate 8 around the optical axis 70 by driving a motor.

[0079] The imaging device 100a emits linearly polarized light 60 from the light source 6. The imaging device 100a drives the variable mechanism 9 to position the quarter-wave plate 8 such that the optical axis of the quarter-wave plate 8 is tilted at -45 degrees with respect to the polarization axis of the light 60. In this case, the light 62 incident on the optical element 1 that has passed through the quarter-wave plate 8 becomes left-handed circularly polarized light. The imaging device 100a also drives the variable mechanism 9 to position the quarter-wave plate 8 such that the optical axis of the quarter-wave plate 8 is tilted at +45 degrees with respect to the polarization axis of the light 60. In this case, the light 62 incident on the optical element 1 that has passed through the quarter-wave plate 8 becomes right-handed circularly polarized light.

[0080] The imaging device 100a can input, to the processing unit 3a, a captured image Im1 obtained when the incident light 62 is left-handed circularly polarized light, and a captured image Im2 obtained when the incident light 62 is right-handed circularly polarized light.

[0081] The imaging device 100a includes the quarter-wave plate 8 and the variable mechanism 9, and thus can cause both left-handed circularly polarized light and right-handed circularly polarized light to be incident on the optical element 1 with a simple configuration.

[0082] <Example of functional configuration of processing unit 3a> Fig. 16 is a block diagram showing an example of a functional configuration of the processing unit 3a. The processing unit 3a has a determination unit 34, a storage unit 35, a first acquisition unit 31a, and a second acquisition unit 32a. The function of the determination unit 34 can be realized by a processor such as the CPU 301 in Fig. 3 executing a process defined in a program stored in a non-volatile memory such as the ROM 302. The function of the storage unit 35 can be realized by the HDD / SSD 304 in Fig. 3, etc.

[0083] The determination unit 34 determines the positions of a plurality of pixels along the outer periphery of the lens 10 based on the first captured image Im1 and the second captured image Im2. For example, the determination unit 34 controls communication with the imaging unit 2 to obtain a first captured image Im1 in which the incident light 62 is left-handed polarized light. The determination unit 34 also controls communication with the imaging unit 2 to obtain a second captured image Im2 in which the incident light 62 is right-handed polarized light.

[0084] The determination unit 34 executes either an image averaging process or an image addition process of the first captured image Im1 and the second captured image Im2. The image averaging process is a process of averaging the luminance of all pixels located at the same coordinates between the first captured image Im1 and the second captured image Im2. The image addition process is a process of adding the luminance of all pixels located at the same coordinates between the first captured image Im1 and the second captured image Im2.

[0085] The determination unit 34 determines the positions of a plurality of pixels along the outer periphery of the lens 10 from an image obtained by image averaging or image addition. The plurality of pixels are, for example, the plurality of pixels included in the outer periphery circle 25 in Fig. 9. The determination unit 34 can determine the positions of a plurality of pixels along the outer periphery of the lens 10 for each of the plurality of lenses 10 included in the optical element 1.

[0086] The storage unit 35 stores information relating to the positions of multiple pixels along the outer periphery of the lens 10 determined by the determination unit 34. The storage unit 35 can store information relating to the positions of multiple pixels along the outer periphery of the lens 10 determined for each of the multiple lenses 10 included in the optical element 1.

[0087] The first acquisition unit 31a acquires polarization information based on the luminance of each of a plurality of pixels corresponding to the positions of the plurality of pixels obtained from the storage unit 35 in a captured image Im acquired by controlling communication with the imaging unit 2. The first acquisition unit 31a can acquire polarization information for each of a plurality of lens peripheral images 21 in the captured image Im.

[0088] The second acquisition unit 32a acquires wavefront information based on the center position of the lens 10 obtained from the positions of the multiple pixels read from the storage unit 35 and the position of the collected image 23 in the lens peripheral image 21 in the captured image Im input from the first acquisition unit 31a. However, the second acquisition unit 32a may acquire the captured image Im from the imaging unit 2 in parallel with the first acquisition unit 31 by controlling communication with the imaging unit 2. The second acquisition unit 32a acquires wavefront information based on the amount of shift d and the direction of shift φ of the position of the collected image of the incident light 62 by the lens 10 relative to the center position of the lens 10. The second acquisition unit 32a can acquire wavefront information for each of the multiple lens peripheral images 21 in the captured image Im.

[0089] <Example of Polarized Light and Wavefront Imaging Results by Imaging Device 100a> With reference to Figs. 17 to 21, the imaging results of polarization and wavefront by the imaging device 100a will be described. Fig. 17 is a diagram showing an example of a lens peripheral image 21a in a first captured image Im1. Fig. 18 is a diagram showing an example of a lens peripheral image 21b in a second captured image Im2. Fig. 19 is a diagram showing an example of an added image 21p of the lens peripheral image 21a in Fig. 17 and the lens peripheral image 21b in Fig. 18. Fig. 20 is a diagram showing the luminance of pixels included in a peripheral circle 25p in the added image 21p in Fig. 19.

[0090] In Fig. 17, the lens peripheral image 21a includes a condensed image 23a, a lens outer edge 24a, and a peripheral circle 25a. In Fig. 18, the lens peripheral image 21b includes a condensed image 23b, a lens outer edge 24b, and a peripheral circle 25b. In Fig. 19, the added image 21p includes a condensed image 23p, a lens outer edge 24p, and a peripheral circle 25p.

[0091] As shown in Fig. 20, the luminance of the multiple pixels included in the outer circumferential circle 25p in Fig. 19 has reduced image noise compared to the luminance of the multiple pixels included in the outer circumferential circle 25 shown in Fig. 9 (see Fig. 10). By using the added image 21p in which the image noise has been reduced in this way, the imaging device 100a can determine the positions of the multiple pixels along the outer periphery of the lens 10 with high accuracy. The imaging device 100a can image the wavefront and polarization of the incident light 62 with high accuracy by using the multiple pixels whose positions have been determined with high accuracy.

[0092] In this embodiment, each time imaging is performed by the imaging device 100a, the first captured image Im1 and the second captured image Im2 may be acquired, and the wavefront and polarization may be imaged using a plurality of added images 21p obtained from the first captured image Im1 and the second captured image Im2. For example, imaging can be performed using the luminance of a plurality of pixels shown in FIG. 20 in which image noise has been reduced, and therefore imaging can be performed with high accuracy.

[0093] The functions and effects other than those shown in this embodiment are substantially the same as those shown in the first embodiment.

[0094] Although the preferred embodiments have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the claims.

[0095] By combining the optical element 1 with an imaging section and a processing section, an imaging device can be constructed in which the wavefront and polarization of light are parallel, and approximately the same effects can be obtained as the imaging device 100 and the imaging device 100a described above.

[0096] The ordinal numbers, quantities, and other numbers used in the description of the embodiments are all provided as examples to specifically explain the technology of the present disclosure, and the present disclosure is not limited to the illustrated numbers. Furthermore, the connection relationships between the components are provided as examples to specifically explain the technology of the present disclosure, and do not limit the connection relationships that realize the functions of the present disclosure.

[0097] The division of blocks in the functional block diagram is an example, and multiple blocks may be realized as one block, one block may be divided into multiple blocks, or some functions may be moved to other blocks. Furthermore, the functions of multiple blocks having similar functions may be processed in parallel or in time-sharing by a single piece of hardware or software. Furthermore, some or all of the functions may be distributed to multiple computers.

[0098] Since the imaging device of the present disclosure can image the wavefront and polarization of light in parallel, it can be suitably used in applications such as cameras or image sensors mounted on automobiles and smartphones, inspection tools for optical components and optical films, and medical devices for evaluating refractive errors after cataract surgery in ophthalmology and for definitively diagnosing amyloidosis. In addition to the above applications, the range of applications is expected to be further expanded to three-dimensional displays, astrophysics, laser science, and early cancer diagnosis in medicine. By combining the optical element of the present disclosure with an imaging unit and a processing unit, an imaging device can be configured with the wavefront and polarization of light in parallel, and can be suitably used in a wide range of applications, similar to the above imaging device.

[0099] Aspects of the present disclosure are, for example, as follows. <1> The imaging device includes an optical element including a plurality of lenses aligned one-dimensionally or two-dimensionally, an imaging unit that images light transmitted through the optical element, and a processing unit that outputs polarization information and wavefront information of light incident on the optical element based on an image captured by the imaging unit, wherein the optical element has polarization characteristics in which the principal axis orientation differs periodically depending on the position along the outer periphery of each of the plurality of lenses. <2> the processing unit includes a first acquisition unit that acquires the polarization information based on the luminance of each of a plurality of pixels along an outer periphery of the lens in the captured image, and a second acquisition unit that acquires the wavefront information based on a center position of the lens and a position of an image of the incident light focused by the lens in the captured image. <1> The imaging device according to the present invention is <3> The imaging device further includes a polarizing member disposed between the imaging unit and the optical element. <1> or the above <2> The imaging device according to the present invention is <4> a determination unit that determines positions of the plurality of pixels based on a first captured image obtained when the incident light is left-handed circularly polarized light and a second captured image obtained when the incident light is right-handed circularly polarized light, the first acquisition unit acquires the polarization information based on the luminance of each of the plurality of pixels whose positions have been determined by the determination unit, and the second acquisition unit acquires the wavefront information based on a center position of the lens and a position of the collected light image obtained from the plurality of pixels whose positions have been determined by the determination unit. <2> The imaging device according to the present invention is <5> the optical element includes a quarter-wave plate that circularly polarizes the light incident on the optical element, and a variable mechanism that changes the orientation of the optical axis of the quarter-wave plate around an axis along the normal direction of the quarter-wave plate so that the optical axis of the quarter-wave plate can be set to either +45 degrees or -45 degrees with respect to the polarization axis of linearly polarized light incident on the quarter-wave plate. <4> The imaging device according to the present invention is <6> In a plan view, the inner regions of the lenses each have polarization characteristics in which the principal axis orientations are randomly different. <1> From the above <5> 1 is an imaging device according to any one of the above items. <7> In the outer periphery of each of the plurality of lenses, the absolute value of the difference between birefringence phase differences at each of a plurality of positions along the outer periphery of the lens is 10 degrees or less; <1> From the above <6> 1 is an imaging device according to any one of the above items. <8> In a plan view, the lens has a shape that is either circular or elliptical. <1> From the above <7> 1 is an imaging device according to any one of the above items. <9> The optical element includes a plurality of lenses aligned one-dimensionally or two-dimensionally, and has polarization characteristics in which the principal axis orientations of the respective outer peripheries of the plurality of lenses vary periodically depending on the position along the outer periphery of the lenses. <10> In a plan view, the inner regions of the lenses each have polarization characteristics in which the principal axis orientations are randomly different. <9> The optical element according to claim 1, <11> In the outer periphery of each of the plurality of lenses, the absolute value of the difference between birefringence phase differences at each of a plurality of positions along the outer periphery of the lens is 10 degrees or less; <9> or the above <10> The optical element according to claim 1, <12> In a plan view, the lens has a shape that is either circular or elliptical. <9> From the above <11> 1 is an optical element according to any one of the above items. [Explanation of symbols]

[0100] 1 Optical elements 1' base 10, 10-1, 10-2 Lenses 11 Lens periphery 11-1 1st position 11-2 2nd position 11-3 3rd position 11-4 4th position 2. Imaging unit 20 Imaging surface 21, 21a, 21b Lens peripheral images 21p Addition Image 22 Center position 23, 23-1, 23-2, 23a, 23b, 23p Focused images 24, 24a, 24b, 24p Lens outer edge 25, 25a, 25b, 25p Outer circle 26 Arrow 27 Oval 3, 3a Processing section 31 First acquisition part 32 Second acquisition part 33 Output section 34 Decision Section 35 Storage area 301 CPU 302 ROM 303 RAM 304 HDD / SSD 305 Connection I / F 4. Chassis 5 Polarizing material 6 light source 60 light 61a, 61a' phase plane 61b, 61b-1, 61b-2 phase point 62 Incident light 7 Collimating Lens 70 Optical axis 8 1 / 4 wave plate 9 Variable Mechanism 81 Laser Light Source 810 Pulsed laser light 82 Objective Lens 83 Duct 84 Translation Stage 841 Table 842 Drive unit 100, 100a Imaging device 200 Laser processing equipment A System Bus d Displacement Im Captured image Im1 First image Im2 2nd image Po Polarization information Q Sample S, S0, S1, S2, S3 Stokes parameters Wf Wavefront information φ Misalignment direction θ angle

Claims

1. an optical element including a plurality of lenses aligned in one or two dimensions; an imaging unit that images light transmitted through the optical element; a processing unit that outputs polarization information and wavefront information of light incident on the optical element based on an image captured by the imaging unit, An imaging device, wherein the optical element has polarization characteristics in which the principal axis orientation periodically differs depending on the position along the outer periphery of each of the plurality of lenses.

2. The processing unit includes: a first acquisition unit that acquires the polarization information based on luminance of each of a plurality of pixels along an outer periphery of the lens in the captured image; The imaging device according to claim 1 , further comprising a second acquisition unit configured to acquire the wavefront information based on a center position of the lens and a position of an image of the incident light focused by the lens in the captured image.

3. The imaging device according to claim 1 , further comprising a polarizing member disposed between the image capturing section and the optical element.

4. a determination unit that determines positions of the plurality of pixels based on a first captured image obtained when the incident light is left-handed circularly polarized light and a second captured image obtained when the incident light is right-handed circularly polarized light, The first acquisition unit acquires the polarization information based on the luminance of each of the plurality of pixels whose positions have been determined by the determination unit; The imaging device according to claim 2 , wherein the second acquisition unit acquires the wavefront information based on a center position of the lens obtained from the plurality of pixels whose positions have been determined by the determination unit and a position of the focused image.

5. a quarter-wave plate that circularly polarizes the light incident on the optical element; and a variable mechanism that varies the orientation of the optical axis of the quarter-wave plate around an axis along a normal direction of the quarter-wave plate so that the optical axis of the quarter-wave plate can be set to either +45 degrees or -45 degrees with respect to the polarization axis of linearly polarized light incident on the quarter-wave plate.

6. 3 . The imaging device according to claim 1 , wherein, in a plan view, inner regions of the plurality of lenses have polarization characteristics in which the principal axis orientations randomly differ.

7. 3. The imaging device according to claim 1, wherein in the outer periphery of each of the plurality of lenses, absolute values ​​of mutual differences in birefringence phase differences at each of a plurality of positions along the outer periphery of the lens are 10 degrees or less.

8. 3. The imaging device according to claim 1, wherein the lens has a shape that is either circular or elliptical in a plan view.

9. a plurality of lenses arranged in one or two dimensions; An optical element, comprising: an optical element having polarization characteristics in which the principal axis orientations periodically differ depending on the position along the outer periphery of each of the plurality of lenses in an outer periphery of the lens.

10. The optical element according to claim 9 , wherein, in a plan view, an inner region of each of the plurality of lenses has polarization characteristics in which the principal axis orientations randomly differ.

11. 11. The optical element according to claim 9, wherein in an outer periphery of each of the plurality of lenses, absolute values ​​of differences between birefringence phase differences at each of a plurality of positions along the outer periphery of the lens are 10 degrees or less.

12. 11. The optical element according to claim 9, wherein the lens has a shape that is either circular or elliptical in a plan view.

Images