Calculation device, calculation method, calculation program, and wavefront sensor

Abstract

This technology provides a method for calculating wavefront aberration even when the alignment of the target focal points is not parallel to the vertical and horizontal grid lines of the target image. [Solution] A reciprocal lattice image (IR) representing the grid point cloud of the reciprocal lattice (XR) is generated by performing a 2D Fourier transform on the target image (IP). Furthermore, by referring to the grid vector of the reciprocal lattice (XR), a target lattice (XP) is estimated in which the arrangement of its grid point cloud approximates the arrangement of the target focal point cloud (P). Then, each target focal point (p i ) at its target focal point (p i The grid point (p) of the target grid (XP) closest to ) mn Assign lattice coordinates to the target focal point (p i ) and reference focal point (q i Pair it with ).

Description

[Technical Field] 【0001】 The present invention relates to a calculation device, a calculation method, and a calculation program for calculating wavefront aberration. It also relates to a wavefront sensor equipped with such a calculation device. [Background technology] 【0002】 A Shack-Hartmann wavefront sensor is known as a device for measuring the wavefront aberration of light. In a Shack-Hartmann wavefront sensor, the wavefront aberration of the target light is measured based on a target image representing the target focal point group obtained by applying a microlens array to the target light, and a reference image representing the reference focal point group obtained by applying a microlens array to a reference light, which is parallel light. Specifically, the target focal point and the reference focal point, formed by the same microlens, are paired, and the amount of movement from the reference focal point to the target focal point is determined for each pair. Then, the amount of wavefront aberration of the target light, such as the Zernike coefficient, is calculated from the amount of movement for each pair. Note that the amount of movement from the reference focal point to the target focal point refers to the amount of movement when the position of the reference focal point is considered as the starting point and the position of the target focal point is considered as the ending point. 【0003】 One known method for pairing a reference focal point with a target focal point is to divide the reference and target images into multiple blocks using equally spaced vertical and horizontal grid lines, and then pair the reference and target focal points belonging to the same block. When the wavefront aberration of the target light is small, the reference and target focal points formed by the same microlens satisfy the condition that they belong to the same block, and are therefore paired. However, when the wavefront aberration of the target light increases, the amount of movement from the reference focal point to the target focal point also increases. In this case, it becomes impossible to pair the reference and target focal points using the method described above. This is because, when the amount of movement increases, the target focal point moves outside the block to which the reference focal point belongs, and the premise that "reference and target focal points formed by the same microlens belong to the same block" no longer holds true. Typical cases where wavefront aberration becomes so large that pairing becomes impossible include cases where the target light is strongly defocused, and cases where the target light contains strong astigmatism. 【0004】 As a technology to address such problems, the wavefront sensor described in Patent Document 1 is known. According to the wavefront sensor described in Patent Document 1, it is possible to pair the reference focal point and the target focal point even when the target light is strongly defocused. [Prior art documents] [Patent Documents] 【0005】 [Patent Document 1] Japanese Patent Publication No. 2010-261810 [Overview of the project] [Problems that the invention aims to solve] 【0006】 However, the technology described in Patent Document 1 enables pairing of a reference focal point and a target focal point only when the condition is met that the direction of alignment of the target focal points is parallel to the vertical and horizontal grid lines of the target image. This condition is met, for example, when the target light is defocused, but not, for example, when the target light contains astigmatism. Therefore, the technology described in Patent Document 1 is applicable, for example, when the target light is defocused, but not applicable, for example, when the target light contains astigmatism. 【0007】 One aspect of the present invention has been made in view of the above-mentioned problems, and its purpose is to provide a technique that can calculate wavefront aberration even when the condition that the direction of alignment of the target focal points is parallel to the vertical and horizontal grid lines of the target image is not met. [Means for solving the problem] 【0008】 A computing device according to one aspect of the present invention includes: a reference focal point detection process that detects each reference focal point belonging to the reference focal point group by referring to a reference image representing a reference focal point group formed by applying a microlens array to a reference light; a target focal point detection process that detects each target focal point belonging to the target focal point group by referring to a target image representing a target focal point group formed by applying the microlens array to a target light; a Fourier transform process that generates a reciprocal lattice image representing a reciprocal lattice point group by performing a two-dimensional Fourier transform on the target image; a reciprocal lattice vector derivation process that derives the reciprocal lattice vector by referring to the reciprocal lattice image generated in the Fourier transform process; and a target lattice that estimates a target lattice whose arrangement of grid points approximates the arrangement of the target focal point group by referring to the reciprocal lattice vector derived in the reciprocal lattice vector derivation process. The process involves: (a) assigning to each target focal point detected in the target focal point detection process the grid coordinates of the grid points of the target grid estimated in the target grid estimation process that are closest to the target focal point; (b) assigning to each reference focal point detected in the reference focal point detection process the grid coordinates of the grid points of the reference grid whose grid point arrangement approximates the arrangement of the reference focal point group that are closest to the reference focal point; (c) performing focal point pairing, which pairs the target focal point and the reference focal point to which the same grid coordinates have been assigned; performing focal point movement amount derivation processing, which derives the amount of movement from the reference focal point to the target focal point that constitutes the pair for each pair paired in the focal point pairing; and performing wavefront aberration amount derivation processing, which derives the amount of wavefront aberration representing the wavefront aberration of the target light by referring to each amount of movement derived in the focal point movement amount derivation processing. 【0009】 A calculation method according to one aspect of the present invention includes: a reference focal point detection process that detects each reference focal point belonging to the reference focal point group by referring to a reference image representing a reference focal point group formed by applying a microlens array to a reference light; a target focal point detection process that detects each target focal point belonging to the target focal point group by referring to a target image representing a target focal point group formed by applying the microlens array to a target light; a Fourier transform process that generates a reciprocal lattice image representing a reciprocal lattice point group by performing a two-dimensional Fourier transform on the target image; a reciprocal lattice vector derivation process that derives the reciprocal lattice vector by referring to the reciprocal lattice image generated in the Fourier transform process; and a target grid that estimates a target grid whose grid point arrangement approximates the arrangement of the target focal point group by referring to the reciprocal lattice vector derived in the reciprocal lattice vector derivation process. The process includes: (a) assigning to each target focal point detected in the target focal point detection process the grid coordinates of the grid points of the target grid estimated in the target grid estimation process that are closest to the target focal point; (b) assigning to each reference focal point detected in the reference focal point detection process the grid coordinates of the grid points of a reference grid whose grid point arrangement approximates the arrangement of the reference focal point group that are closest to the reference focal point; (c) pairing target focal points and reference focal points to which the same grid coordinates have been assigned; a focal point movement amount derivation process for each pair paired in the focal point pairing, deriving the amount of movement from the reference focal point to the target focal point that constitutes the pair; and a wavefront aberration amount derivation process for deriving a wavefront aberration amount representing the wavefront aberration of the target light by referring to each movement amount derived in the focal point movement amount derivation process. 【0010】 A calculation program according to one aspect of the present invention includes, on at least one processor: a reference focal point detection process that detects each reference focal point belonging to the reference focal point group by referring to a reference image representing a reference focal point group formed by applying a microlens array to a reference light; a target focal point detection process that detects each target focal point belonging to the target focal point group by referring to a target image representing a target focal point group formed by applying the microlens array to a target light; a Fourier transform process that generates a reciprocal lattice image representing a reciprocal lattice point group by performing a two-dimensional Fourier transform on the target image; a reciprocal lattice vector derivation process that derives the reciprocal lattice vector by referring to the reciprocal lattice image generated in the Fourier transform process; and a target lattice whose arrangement of grid points approximates the arrangement of the target focal point group by referring to the reciprocal lattice vector derived in the reciprocal lattice vector derivation process. The system performs the following steps: (a) assigning to each target focal point detected in the target focal point detection process the grid coordinates of the grid points of the target grid estimated in the target focal point estimation process that are closest to the target focal point; (b) assigning to each reference focal point detected in the reference focal point detection process the grid coordinates of the grid points of a reference grid whose grid point arrangement approximates the arrangement of the reference focal point group that are closest to the reference focal point; (c) pairing the target focal point and the reference focal point to which the same grid coordinates have been assigned; a focal point movement amount derivation process for each pair paired in the focal point pairing, which derives the amount of movement from the reference focal point to the target focal point that constitutes the pair; and a wavefront aberration amount derivation process for deriving the wavefront aberration amount representing the wavefront aberration of the target light by referring to each movement amount derived in the focal point movement amount derivation process. [Effects of the Invention] 【0011】 According to one aspect of the present invention, wavefront aberration can be calculated even when the condition that the direction of alignment of the target focal points is parallel to the vertical and horizontal grid lines of the target image is not met. [Brief explanation of the drawing] 【0012】 [Figure 1] This is a schematic diagram showing an example of a reference image representing a reference focal point group. [Figure 2] This is a schematic diagram showing an example of a target image representing a target cluster of light-gathering points. [Figure 3] This is a schematic diagram showing an example of a target image representing a target cluster of light-gathering points. [Figure 4] A block diagram showing the configuration of a computing device relating to one embodiment of the present invention. [Figure 5] This is a flowchart showing the flow of the calculation method related to one embodiment of the present invention. [Figure 6] This figure shows specific examples of the original image, the simplified image, and the reciprocal grid image used in the calculation method shown in Figure 5. [Figure 7] This is a block diagram showing the main components of a wavefront sensor according to one embodiment of the present invention. [Figure 8] This is a block diagram showing a first modified example of the wavefront sensor shown in Figure 7. [Figure 9] Figure 7 is a block diagram showing a second modified example of the wavefront sensor. [Figure 10] This is a block diagram showing a third modified example of the wavefront sensor shown in Figure 7. [Figure 11] Figure 7 shows a reference image acquired by the wavefront sensor through the reference image acquisition process. [Figure 12] (a) is a diagram showing the target image acquired by the wavefront sensor shown in Figure 7 through the target image acquisition process. (b) is a diagram showing the simplified target image generated by the wavefront sensor shown in Figure 7 through the target image simplification process. [Figure 13] Figure 7 shows the reciprocal lattice image generated by the wavefront sensor through Fourier transform processing. [Figure 14] (a) is a diagram showing the grid points of the target grid estimated by the wavefront sensor shown in Figure 7 through target grid estimation processing. (b) is a diagram showing the grid coordinates assigned to each target focal point in focal point pairing by the wavefront sensor shown in Figure 7. [Figure 15](a) is a diagram showing the results of focusing point pairing when the target light is defocused. (b) is a diagram showing the results of focusing point pairing when the target light has astigmatism. [Modes for carrying out the invention] 【0013】 [Definition of Terms] The embodiments described below relate to a Shack-Hartmann type wavefront sensor. A Shack-Hartmann type wavefront sensor is a device for measuring the wavefront aberration of light using a microlens array in which microlenses are arranged in a square grid. 【0014】 In this specification, the light source whose wavefront aberration is to be measured is referred to as the "target light" (LP). Furthermore, the parallel light source used as a reference for measuring the wavefront aberration of the target light (LP) is referred to as the "reference light" (LQ). 【0015】 In this specification, the set of focal points formed by applying a microlens array to a reference light LQ is referred to as the "reference focal point group" Q, and each focal point belonging to the reference focal point group Q is referred to as the "reference focal point" q. i It is stated as follows: Reference focusing point q i Let M be the number of such points, and i is a natural number less than or equal to M. Furthermore, the image representing the two-dimensional distribution (spot diagram) of the reference point group Q is referred to as the "reference image" IQ. Figure 1 is a schematic diagram showing an example of a reference image IQ representing the reference point group Q. 【0016】 Among the reference images IQ, the image generated by a two-dimensional image sensor when a microlens array is applied to the reference light LQ to form a reference focal point group Q on that two-dimensional image sensor is referred to as the "original reference image" IQ1. 【0017】 Each reference focal point q belonging to the reference focal point group Q i The position coordinates r(q i )=(x,y) can be assigned. Reference focusing point q i Position coordinates r(qi ) can be defined using, for example, the pixel coordinates of the pixel in the reference image IQ where the reference focus point q i is located. Here, pixel coordinates refer to the coordinates assigned to each pixel of the reference image IQ. The method of assigning pixel coordinates is arbitrary. As an example, the coordinates of the pixel located at the upper left corner of the reference image IP are set as (0,0), the coordinates of the pixel existing x pixels to the right from the pixel at the coordinates (0,0) are set as (x,0), and the coordinates of the pixel existing y pixels downward from the pixel at the coordinates (x,0) are set as (x,y). Note that the pixel serving as the origin, that is, the pixel to which the coordinates (0,0) are assigned, is arbitrary. Also, regarding the x coordinate, either the left or right direction may be set as the positive direction, and regarding the y coordinate, either the up or down direction may be set as the positive direction. 【0018】 Note that the position coordinates r(q i ) of the reference focus point q i can be defined using the cell coordinates of the cell (photoelectric conversion element) in the two-dimensional image sensor where the reference focus point q i is located. When each pixel constituting the reference image IQ and each cell constituting the two-dimensional image sensor correspond one-to-one, the position coordinates r(q i ) of the reference focus point q i defined using the pixel coordinates of the reference image IQ is the same as the position coordinates r(q i ) of the reference focus point q i defined using the cell coordinates of the two-dimensional image sensor. 【0019】 The reference light LQ is parallel light. Therefore, the arrangement of the reference focus point group Q is approximated by the arrangement of the lattice point group of a square lattice determined according to the positional relationship between each microlens constituting the microlens array and each cell (photoelectric conversion element) constituting the two-dimensional image sensor (see FIG. 1). Hereinafter, the square lattice in which the arrangement of the lattice point group approximates the arrangement of the reference focus point group Q, that is, the square lattice in which the reference focus point q i exists near each lattice point is described as the "reference lattice" XQ. 【0020】 As described above, the reference grating XQ is determined by the positional relationship between each microlens constituting the microlens array and each cell (photoelectric conversion element) constituting the two-dimensional image sensor. In other words, the reference grating XQ is a known grating in the sense that it can be predetermined before starting wavefront aberration measurements. When measuring an ideal reference light LQ without wavefront aberration using an ideal measurement optical system without optical aberrations, the arrangement of the reference focusing point group Q coincides with the arrangement of the grating point group of the reference grating XQ. 【0021】 In this specification, the set of focal points formed by applying a microlens array to the target light LP is referred to as the "target focal point group" P, and each focal point belonging to the target focal point group P is referred to as the "target focal point" p i It is written as follows: Target focusing point p i Let N be the number of such points, where i is a natural number less than or equal to N. Furthermore, the image representing the two-dimensional distribution (spot diagram) of the target cluster of points P is referred to as the "target image" IP. Figures 2 and 3 are schematic diagrams showing an example of a target image IP representing the target cluster of points P. 【0022】 Of the target image IPs, the image generated by the 2D image sensor when a microlens array is applied to the target light LP to form a target condensed point group P on the 2D image sensor is referred to as the "original target image" IP1. Furthermore, of the target image IPs, the image obtained by applying the simplification process described later to the original target image IP1 is referred to as the "simplified target image" IP2. 【0023】 Each target condensation point p belonging to the target condensation point group P i The position coordinates r(p i )=(x,y) can be assigned. Target focal point p i Position coordinates r(p i ) is, for example, the target condensation point p among the pixels that make up the target image IP. iIt can be defined using the pixel coordinates of the pixel on which it is located. Here, pixel coordinates refer to the coordinates assigned to each pixel of the target image IP. The method of assigning pixel coordinates is arbitrary, but as an example, the coordinates of the pixel located in the upper left corner of the target image IP can be set to (0,0), the coordinates of the pixel located x pixels to the right of the pixel at coordinate (0,0) can be set to (x,0), and the coordinates of the pixel located y pixels down from the pixel at coordinate (x,0) can be set to (x,y). Note that the pixel to be used as the origin, i.e., the pixel to which the coordinate (0,0) is assigned, can be arbitrary. Furthermore, regarding the x coordinate, either the left or right direction can be considered the positive direction, and regarding the y coordinate, either the up or down direction can be considered the positive direction. 【0024】 Note that the target focal point p i Position coordinates r(p i ) refers to the target focusing point p of the cell (photoelectric conversion element) that constitutes the 2D image sensor. i The target focal point p may be defined using the cell coordinates of the cell in which it is located. When each pixel constituting the target image IP corresponds one-to-one with each cell constituting the 2D image sensor, the target focal point p is defined using the pixel coordinates of the target image IP. i Position coordinates r(p i ) is the target focal point p defined using the cell coordinates of the 2D image sensor. i Position coordinates r(p i ) matches. 【0025】 The arrangement of the target condensing point group P in the target image IP is determined not only by the positional relationship between each microlens constituting the microlens array and each cell (photoelectric conversion element) constituting the 2D image sensor, but also by the wavefront aberration of the target light LP. For example, if the target light LP is focused light, the arrangement of the target condensing point group P is approximated by the arrangement of the grid point group of a square grid with a narrower grid spacing than the reference grid XQ described above (see Figure 2). Also, if the target light LP is divergent light, the arrangement of the target condensing point group P is approximated by the arrangement of the grid point group of a square grid with a wider grid spacing than the reference grid XQ described above. Furthermore, if the target light LP contains astigmatism (for example, light transmitted through a cylindrical lens), the arrangement of the target condensing point group P is approximated by the arrangement of the grid point group of a general grid (a grid with a parallelogram unit pack) (see Figure 3). Hereinafter, the grid whose grid point group arrangement approximates the arrangement of the target condensing point group P is described, that is, the target condensing point p is located near each grid point. i The lattice in which this exists is referred to as the "target lattice" XP. 【0026】 As described above, the target grid XP is determined not only by the positional relationship between each microlens constituting the microlens array and each cell (photoelectric conversion element) constituting the 2D image sensor, but also by the wavefront aberration of the target light LP. In other words, the target grid XP is an unknown grid in the sense that it cannot be predetermined before starting the measurement of wavefront aberration. In the embodiment described below, the target grid XP is determined from the reciprocal grid XR obtained by performing a 2D Fourier transform on the target focal point group P. 【0027】 [Problems to be solved by the embodiment] To measure the wavefront aberration of the target light LP, each target focal point p belonging to the target focal point group P is measured. i Regarding the target focal point p, i Reference focal point q formed by the same microlens i From the target focusing point p i Distance traveled to δ(q) i ,p i Therefore, it is necessary to know the wavefront aberration of the target light LP, and each target focal point p belonging to the target focal point group P. iFor this, the target focal point p i Reference focal point q formed by the same microlens i You need to pair them. 【0028】 Traditionally, this pairing method involved dividing the reference image IP and target image IQ into blocks. The reference image IQ can be divided into multiple blocks by equally spaced vertical and horizontal grid lines such that the grid points of the reference grid XR are located at the center of each block (see Figure 1). The target image IP can also be divided into multiple blocks by the same grid lines used to divide the reference image IQ (see Figures 2 and 3). 【0029】 When the wavefront aberration of the target light LP is sufficiently small, each target focal point p i The reference focusing point q to pair with i As a method for selecting the target focal point p, i Reference focal point q belonging to the same block i A method of selecting can be adopted because the smaller the wavefront aberration of the target light LP, the smaller each target focal point p i The position is the target focal point p i Reference focal point q formed by the same microlens i It approaches the position. Therefore, if the wavefront aberration of the target light LP is sufficiently small, each target focal point p i The block to which the target image IP belongs is the target light collection point p i Reference focal point q formed by the same microlens i This is because it is guaranteed that it will match the block to which it belongs in the reference image IQ. 【0030】 On the other hand, if the wavefront aberration of the target light LP is large, each target focal point p i The reference focusing point q to pair with i As a method for selecting the target focal point p, i Reference focal point q belonging to the same block i We cannot adopt a method of selecting this because the wavefront aberration of the target light LP increases, each target focal point pi The position is the target focal point p i Reference focal point q formed by the same microlens i It moves away from the position. Therefore, if the wavefront aberration of the target light LP is large, each target focal point p i The block to which the target image IP belongs is the target light collection point p i Reference focal point q formed by the same microlens i This is because it is not guaranteed that the image will correspond to the block it belongs to in the reference image IQ. 【0031】 The embodiments described below have been made in view of the above-mentioned problems, and their purpose is to enable the formation of a target focal point p by the same microlens, regardless of the magnitude of the wavefront aberration of the target light LP. i and reference focusing point q i The objective is to provide a method for pairing the following: the paired reference focal point q i From the target focusing point p i Distance traveled to δ(q) i ,p i The objective is to provide a method for deriving a wavefront aberration quantity (e.g., Zernike coefficient) that represents the wavefront aberration of a target optical LP using ). 【0032】 [Configuration of the computing unit] The configuration of the arithmetic unit 1 according to one embodiment of the present invention will be described with reference to Figure 4. Figure 4 is a block diagram showing the configuration of the arithmetic unit 1. 【0033】 In this embodiment, a single general-purpose computer is used as the arithmetic unit 1. As shown in Figure 4, the arithmetic unit 1 includes memory 11, a processor 12, and storage 13, and performs the arithmetic method S1 described later. 【0034】 The memory 11, processor 12, and storage 13 are connected to each other via a bus (not shown). An input / output interface (not shown) and a communication interface (not shown) may also be connected to this bus. 【0035】 The input / output interface is used, for example, to input information from an external device (e.g., a keyboard) to the arithmetic unit 1, or to output information from the arithmetic unit 1 to an external device (e.g., a display). The communication interface is used, for example, to receive information from an external device (e.g., another computer), or to transmit information to an external device (e.g., another computer). The acquisition of the original target image IP1 and the original reference image IQ1 is performed, for example, via the input / output interface or the communication interface. 【0036】 Memory 11 is configured to temporarily store (for example, volatile storage) the calculation program P. Memory 11 is also used to temporarily store various data acquired or generated during the process of performing the calculation method S1, which will be described later, such as the original target image IP1 and the simplified target image IP2. For example, semiconductor RAM (Random Access Memory) can be used as memory 11. 【0037】 The processor 12 is configured to execute each step included in the calculation method S1 described later, according to the calculation program P loaded into the memory 11. For example, the processor 12 can be a CPU (Central Processing Unit), a GPU (Graphic Processing Unit), a TPU (Tensor Processing Unit), a digital signal processor, a microprocessor, a microcontroller, or a combination thereof. 【0038】 The storage 13 is configured to non-temporarily store the calculation program P (for example, in non-volatile storage). The storage 13 is also used to non-temporarily store various data acquired or generated during the execution of the calculation method S1, which will be described later, such as the original target image IP1 and the simplified target image IP2. The processor 12 loads the calculation program P, which is non-temporarily stored in the storage 13, onto the memory 11 and accesses it. The same applies to various data acquired or generated during the execution of the calculation method S1, which will be described later, such as the original target image IP1 and the simplified target image IP2. For example, the storage 13 can be flash memory, an HDD (Hard Disk Drive), an SSD (Solid State Drive), or a combination thereof. 【0039】 In this embodiment, the arithmetic method S1 is executed by a single processor (for example, processor 12) provided in a single computer, but the present invention is not limited thereto. That is, it is also possible to employ a configuration in which the arithmetic method S1 is executed collaboratively by multiple processors, either centrally located in a single computer or distributed across multiple computers. 【0040】 The arithmetic program P for causing the processor 12 to execute the arithmetic method S1 may be recorded on a computer-readable, non-temporary, tangible recording medium. This recording medium may be memory 11, storage 13, or other recording media. For example, tape, disk, card, semiconductor memory, and programmable logic circuits can be used as other recording media. 【0041】 [Calculation method flow] The flow of the calculation method S1 according to one embodiment of the present invention will be explained with reference to Figures 5 and 6. Figure 5 is a flowchart showing the flow of the calculation method S1. Figure 6 is a schematic diagram showing specific examples of the original target image IP1, the simplified target image IP2, and the reciprocal grid image IR used in the calculation method S1. 【0042】 As shown in Figure 5, the calculation method S1 includes a target image acquisition process S11a, a reference image acquisition process S11b, a target focal point detection process S12a, a reference focal point detection process S12b, a target image simplification process S13, a Fourier transform process S14, a reciprocal lattice vector derivation process S15, a target lattice estimation process S16, a focal point pairing process S17, a focal point shift amount derivation process S18, and a wavefront aberration amount derivation process S19. In this embodiment, each process included in the calculation method S1 is executed by the processor 12 of the arithmetic unit 1. 【0043】 The target image acquisition process S11a is the process of acquiring the original target image IP1. As described above, the original target image IP1 refers to the image generated by the 2D image sensor when a microlens array is applied to the target light LP to form a target focal point group P on the 2D image sensor. An example of the original target image IP1 is shown in Figure 6. Note that the original target image IP1 shown in Figure 6 is the actual original target image IP1 with the colors inverted to black and white. 【0044】 The reference image acquisition process S11b is the process of acquiring the original reference image IQ1. As described above, the original reference image IQ1 refers to the image generated by the 2D image sensor when a microlens array is applied to the reference light LQ to form a target focal point group Q on the 2D image sensor. 【0045】 The target condensation point detection process S12a refers to the original target image IP1 acquired in the target image acquisition process S11a and selects each target condensation point p belonging to the target condensation point group P. i It detects the position coordinates r(p i This is the process of identifying each target light-gathering point p in the original target image IP1. i It detects the position coordinates r(p i As an algorithm to identify the peaks, for example, a known peak detection algorithm can be used. However, in the original target image IP1, each target condensation point p i It detects the position coordinates r(p i The algorithm used to identify ) is not limited to this and is arbitrary. 【0046】 The reference focusing point detection process S12b refers to the original reference image IQ1 acquired in the target image acquisition process S11a and selects each reference focusing point q belonging to the reference focusing point group Q. i It detects the position coordinates r(q i This is the process of identifying each reference focal point q in the original reference image IQ1. i It detects the position coordinates r(p i As an algorithm to identify the peaks, for example, a known peak detection algorithm can be used. However, in the original reference image IQ1, each target focal point p i It detects the position coordinates r(p i The algorithm used to identify ) is not limited to this and is arbitrary. 【0047】 Note that each reference focal point q belongs to the reference focal point group Q. i Position coordinates r(q i The reference focal point q belonging to the reference focal point q is determined by the positional relationship between each microlens constituting the microlens array and each cell (photoelectric conversion element) constituting the 2D image sensor, and is invariant. Therefore, the reference image acquisition process S11b and the reference focal point detection process S12b only need to be performed in the first measurement and do not need to be performed in subsequent measurements. Furthermore, the reference focal point group Q is approximated by the grid point group of a known reference grid XQ. Therefore, each reference focal point q belonging to the reference focal point group Q is approximated by the grid point group of a known reference grid XQ. i Position coordinates r(q i ) can also be replaced with the position coordinates of each grid point of the known reference grid XQ. In this case, the reference image acquisition process S11b and the reference focal point detection process S12b can be omitted even in the first measurement. 【0048】 The target image simplification process S13 is a process that generates a simplified target image IP2 by simplifying the original target image IP1 acquired in the target image acquisition process S11a. The simplified target image IP2 is, for example, each target light collection point p i This is a binary image in which the pixel corresponding to the point p takes a pixel value of "1" and the pixel value of all other pixels takes a pixel value of "0". Alternatively, the target focal point pi This is a binary image in which pixels in the vicinity of the point have a pixel value of "1", and all other pixels have a pixel value of "0". Here, the target focal point p i The neighborhood of a pixel refers, for example, to a circular region centered on that pixel, or a rectangular region centered on that pixel. Also, the target condensation point p i The maximum pixel value is taken at the corresponding pixel, and the target condensation point p i In the vicinity of the pixel, the target focal point p i A multi-level image can be used as the simplified image IP2 by taking intermediate pixel values ​​according to the distance from a certain point and taking the minimum pixel value for the remaining pixels. Here, any decreasing function can be used as the function that determines the intermediate pixel values. An example of the simplified image IP2 is shown in Figure 6. Note that the simplified image IP2 shown in Figure 6 is the actual simplified image IP2 with the colors inverted. 【0049】 The simplified image IP2 can be considered an image from which non-uniform information such as electronic noise and differences in brightness of the target focal point has been removed from the original image IP1. Performing the following processing using the simplified image IP2 results in higher processing accuracy than performing the following processing using the original image IP1. 【0050】 The Fourier transform process S14 generates a reciprocal lattice image IR by applying a two-dimensional Fourier transform to the simplified target image IP2 generated in the target image simplification process S13. Generally, when a two-dimensional Fourier transform is applied to an image representing a point cloud that is roughly arranged periodically, i.e., a point cloud approximated by the grid point cloud of a certain two-dimensional grid, an image representing the grid point cloud of the reciprocal grid with respect to that two-dimensional grid is obtained. If the arrangement of the target condensing point cloud P represented by the simplified target image IP2 is approximated by the arrangement of the grid point cloud of a certain target grid XP, the reciprocal lattice image IR generated in the Fourier transform process S14 will be an image representing the grid point cloud of the reciprocal grid XR with respect to that target grid XP. An example of a reciprocal lattice image IR is shown in Figure 6. Note that the reciprocal lattice image IR shown in Figure 6 is an inverted version of the actual reciprocal lattice image IR. 【0051】 The reciprocal lattice vector derivation process S15 is a process that derives the lattice vectors U1 and U2 of the reciprocal lattice XR by referring to the reciprocal lattice image IR generated in the Fourier transform process S14. As can be seen from the enlarged view of the reciprocal lattice image IR shown in Figure 6, the reciprocal lattice image IR has the following characteristics. First, there is a lattice point r0 of the reciprocal lattice XR at the center of the reciprocal lattice image IR. Second, there are four lattice points r1, r2, r3, and r4 of the reciprocal lattice XR that are nearest to lattice point r0. Therefore, in the reciprocal lattice vector derivation process S15, first, four vectors u1, u2, u3, and u4 are identified, with lattice point r0 as the starting point and the four lattice points r1, r2, r3, and r4 as the ending points, respectively. Then, two of the identified four vectors u1, u2, u3, and u4 that are linearly independent are selected as the lattice vectors U1 and U2 of the reciprocal lattice XR. 【0052】 The target grid estimation process S16 is a process that estimates the target grid XP whose grid point arrangement approximates the arrangement of the target light-gathering point group P, by referring to the grid vectors U1 and U2 of the reciprocal grid XR derived in the reciprocal grid vector derivation process S15. In the target grid estimation process S16, first, (a) the grid vectors V1 and V2 of the target grid XP are derived by referring to the grid vectors U1 and U2 of the reciprocal grid XR derived in the reciprocal grid vector derivation process S15, and then, (b) the grid points p' of the target grid XP are determined by referring to the grid vectors V1 and V2 of the target grid XP. mn Derive the following. 【0053】 To derive the lattice vectors V1 and V2 of the target lattice XP, for example, equations (1) and (2) below can be used. The R that appears in equations (1) and (2) below is a matrix defined by equation (3) below. 【number】 【number】 【number】 【0054】 Lattice point p' of the target lattice XP mn For the derivation of, for example, the following formula (4) is used. Here, (m, n) is the lattice coordinates of the lattice point p' of the target lattice XP mn is. 【Number】 【0055】 On the other hand, for the lattice point q' having lattice coordinates (m, n) with respect to the reference lattice XQ whose arrangement of the lattice point group approximates the arrangement of the reference set of light spot group Q mn is given by the following formula (5). The lattice vectors W1 and W2 appearing in the following formula (5) are the lattice vectors W1 and W2 of the reference lattice XQ determined according to the positional relationship between each microlens constituting the microlens array and each cell (photoelectric conversion element) constituting the two-dimensional image sensor. 【Number】 【0056】 Here, the lattice vectors W1 and W2 of the reference lattice XQ may be derived from the positional relationship between each microlens constituting the microlens array and each cell (photoelectric conversion element) constituting the two-dimensional image sensor, or may be derived by referring to the reference image IQ. As a method for deriving the lattice vectors W1 and W2 of the reference lattice XQ by referring to the reference image IQ, a method similar to the method for deriving the lattice vectors U1 and U2 of the reciprocal lattice XR by referring to the reciprocal lattice image IR can be used. 【0057】 In the reciprocal lattice vector derivation process S15, as described above, four vectors u1, u2, u3, u4 shown in FIG. 6 are specified. The lattice vectors U1, U2 of the reciprocal lattice XR are selected from the four vectors u1, u2, u3, u4 so as to satisfy the following conditions in addition to the fact that they are linearly independent of each other as described above. Condition 1: The lattice vector V1 of the target lattice XP derived from the lattice vectors U1, U2 of the reciprocal lattice XR according to Equation (1) is the vector that forms the smallest angle with the lattice vector W1 of the reference lattice XQ among the four vectors V1, V2, -V1, -V2. Condition 2: The lattice vector V2 of the target lattice XP derived from the lattice vectors U1, U2 of the reciprocal lattice XR according to Equation (2) is the vector that forms the smallest angle with the lattice vector W2 of the reference lattice XQ among the four vectors V1, V2, -V1, -V2. 【0058】 The condensing point pairing process S17 is a process for pairing each target condensing point p detected in the target condensing point detection process S12a i and each reference condensing point q detected in the reference condensing point detection process S12b i In the condensing point pairing process S17, (a) for each target condensing point p detected in the target condensing point detection process S12a i among the lattice points of the target lattice XP, the lattice coordinates (m, n) of the lattice point p' i closest to the target condensing point p mn are assigned, (b) for each reference condensing point q detected in the reference condensing point detection process S12b i among the lattice points of the reference lattice XR, the lattice coordinates (m, n) of the lattice point q' mn closest to the reference condensing point qi are assigned, and (c) the target condensing point p i and the reference condensing point q i to which the same lattice coordinates (m, n) are assigned are paired. 【0059】 Note that when the distance d between the target condensing point p i and the lattice point p' i of the target lattice XP closest to the target condensing point p mn satisfies the following Equation (6), the corresponding reference condensing point q iPairing will not be performed, assuming that the item does not exist. This is an exception to handle cases where a focal point is missing due to reasons such as the presence of an obstruction inside the optical system or the inability to detect a specific focal point due to differences in brightness between focal points. 【number】 【0060】 For each pair formed in the focusing point movement amount derivation process S18 and the focusing point pairing process S17, the reference focusing point q that constitutes that pair i Therefore, the target focusing point p that constitutes that pair i Transfer amount δ(q i ,p i ) = r(p i )-r(q i This is the process of deriving ). Here, r(p i ) is the target focal point p identified in the target focal point detection process S12a. i These are the position coordinates. Also, r(q i ) is the reference focusing point q identified in the reference focusing point detection process S12b. i These are the position coordinates. 【0061】 Wavefront aberration derivation process S19 uses each of the displacement amounts δ(q) derived in the focal point displacement derivation process S18. i ,p i This process derives the wavefront aberration amount representing the wavefront aberration of the target optical LP by referring to ( ). Examples of wavefront aberration amounts derived in wavefront aberration amount derivation process S19 include the Zernike coefficient. Each displacement amount δ(q) derived in focal point displacement amount derivation process S18 i ,p i The algorithm for deriving the Zernike coefficients from ) is publicly known, so its explanation will be omitted here. 【0062】 [Wavefront sensor configuration] The configuration of the wavefront sensor 100 according to one embodiment of the present invention will be described with reference to Figure 7. Figure 7 is a block diagram showing the main components of the wavefront sensor 100. 【0063】 The wavefront sensor 100 is a device for measuring the wavefront aberration of light transmitted through the object to be inspected 2. The wavefront sensor 100 comprises a measuring light source 101, a collimating lens 102, a beam expander 103, a relay optical system 104, a microlens array 105, a two-dimensional image sensor 106, and a computing device 107. 【0064】 The collimating lens 102, beam expander 103, relay optical system 104, microlens array 105, and two-dimensional image sensor 106 are arranged in this order along the optical path of the light L output from the measurement light source 101. The object to be inspected 2 is placed between the beam expander 103 and the relay optical system 104. 【0065】 The measurement light source 101 is configured to generate monochromatic light L. For example, an LED (Light Emitting Diode), SLD (Super Luminescent Diode), or LD (Laser Diode) can be used as the measurement light source 101. The collimating lens 102 is configured to collimate the light L emitted from the measurement light source 101. The beam expander 103 is configured to expand the beam diameter of the light L emitted from the collimating lens 102 to approximately the same size as the object being inspected 2. The beam expander 103 is composed of, for example, two convex lenses 103a and 103b with different focal lengths. Both the light emitted from the collimating lens 102 and the light L emitted from the beam expander 103 are parallel light. 【0066】 The relay optical system 104 is configured to relay the light L emitted from the beam expander 103. The relay optical system 104 is composed of, for example, two convex lenses 104a and 104b with equal focal lengths. The microlens array 105 is composed of a plurality of microlenses arranged in a square grid. Each microlens constituting the microlens array 105 focuses the light L emitted from the relay optical system 104 onto the two-dimensional image sensor 106. As a result, a group of focusing points, which is a collection of focusing points formed by each microlens constituting the microlens array 105, is formed on the two-dimensional image sensor 106. 【0067】 The two-dimensional image sensor 106 is configured to generate a two-dimensional image representing the cluster of light-gathering points formed by the microlens array 105. A CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor can be used as the two-dimensional image sensor 106. The two-dimensional image generated by the two-dimensional image sensor 106 is transmitted to the computing unit 107. 【0068】 If the object to be inspected 2 is not placed between the beam expander 103 and the relay optical system 104, the wavefront aberration-free light L, i.e., the reference light LQ described above, emitted from the beam expander 103 is incident on the microlens array 105 via the relay optical system 104, and the reference focused point group Q described above is formed on the two-dimensional image sensor 106. The original reference image IQ1 described above is a two-dimensional image generated by the two-dimensional image sensor 106 at this time. 【0069】 On the other hand, when the object to be inspected 2 is placed between the beam expander 103 and the relay optical system 104, the wavefront aberration-affected light L that has passed through the object to be inspected 2, i.e., the target light LP described above, is incident on the microlens array 105 via the relay optical system 104, and the target focused point group P described above is formed on the two-dimensional image sensor 106. The original target image IP1 described above is a two-dimensional image generated by the two-dimensional image sensor 106 at this time. 【0070】 The arithmetic unit 107 is configured to measure the wavefront aberration of the target light LP by referring to the original target image IP1 and the original reference image IQ1 generated by the two-dimensional image sensor 106. The arithmetic unit 1 described above is used as the arithmetic unit 107. The arithmetic unit 107 calculates the wavefront aberration amount (e.g., Zernike coefficient) representing the wavefront aberration of the target light LP by performing the calculation method S1 described above. 【0071】 In Figure 7, a convex lens is shown as the object to be inspected 2, but this is not the only example. For example, a concave lens may be used as the object to be inspected 2, or a lens that has refractive power in only one direction, such as a cylindrical lens, may be used as the object to be inspected 2. Furthermore, any optical element that transmits light, or a combination thereof, can be used as the object to be inspected 2. 【0072】 [Example 1 of wavefront sensor] A first modified example of the wavefront sensor 100 described above (hereinafter referred to as wavefront sensor 100A) will be explained with reference to Figure 8. Figure 8 is a block diagram showing the main components of wavefront sensor 100A. 【0073】 The wavefront sensor 100A is a device for measuring the wavefront aberration of light reflected from the object under inspection 2. The wavefront sensor 100A is a modified version of the wavefront sensor 100 described above, with the addition of a beam splitter 108. 【0074】 The collimating lens 102, beam expander 103, and beam splitter 108 are arranged in this order along the optical path of the light L output from the measurement light source 101. The object to be inspected 2 is placed on the optical path of the light L that has been emitted from the beam expander 103 and then passed through the beam splitter 108. The relay optical system 104, microlens array 105, and two-dimensional image sensor 106 are arranged in this order along the optical path of the light L that has been reflected by the object to be inspected 2 and then reflected by the beam splitter 108. 【0075】 When the object to be inspected 2 is placed in the optical path of the light L that has passed through the beam splitter 108, the wavefront aberrated light L reflected by the object to be inspected 2, i.e., the target light LP described above, is incident on the microlens array 105 via the beam splitter 108 and the relay optical system 104, and the target concentrated point group P described above is formed on the two-dimensional image sensor 106. The original target image IP1 described above is a two-dimensional image generated by the two-dimensional image sensor 106 at this time. 【0076】 When a plane mirror is placed in place of the object to be inspected 2 on the optical path of the light L that has passed through the beam splitter 108, the wavefront aberration-free light L reflected by the plane mirror, i.e., the reference light LQ described above, is incident on the microlens array 105 via the beam splitter 108 and the relay optical system 104, and the reference focused point group Q described above is formed on the two-dimensional image sensor 106. The original reference image IQ1 described above is a two-dimensional image generated by the two-dimensional image sensor 106 at this time. 【0077】 The arithmetic unit 107 is configured to measure the wavefront aberration of the target light LP by referring to the original target image IP1 and the original reference image IQ1 generated by the two-dimensional image sensor 106. The arithmetic unit 1 described above is used as the arithmetic unit 107. The arithmetic unit 107 calculates the wavefront aberration amount (e.g., Zernike coefficient) representing the wavefront aberration of the target light LP by performing the calculation method S1 described above. 【0078】 In Figure 8, a concave mirror is shown as the object to be inspected 2, but it is not limited to this. For example, a convex mirror may also be used as the object to be inspected 2. Any optical element that reflects light can be used as the object to be inspected 2. 【0079】 [Modified example of wavefront sensor 2] A second modified example of the wavefront sensor 100 described above (hereinafter referred to as wavefront sensor 100B) will be explained with reference to Figure 9. Figure 9 is a block diagram showing the main components of wavefront sensor 100B. 【0080】 The wavefront sensor 100B is a device for measuring the wavefront aberration of light transmitted through the object 2 to be inspected. The wavefront sensor 100B is a modified version of the wavefront sensor 100 described above, with the addition of a beam splitter 108 and a plane mirror 109. 【0081】 The collimating lens 102, beam expander 103, and beam splitter 108 are arranged in this order along the optical path of the light L output from the measurement light source 101. The plane mirror 109 is placed on the optical path of the light L that has been emitted from the beam expander 103 and passed through the beam splitter 108. The relay optical system 104, microlens array 105, and two-dimensional image sensor 106 are arranged in this order along the optical path of the light L that has been reflected by the plane mirror 109 and then reflected by the beam splitter 108. The object to be inspected 2 is placed between the beam splitter 108 and the plane mirror 109. 【0082】 When the object to be inspected 2 is placed between the beam splitter 108 and the plane mirror 109, the wavefront aberration-affected light L that has passed through the object to be inspected 2, i.e., the target light LP described above, is incident on the microlens array 105 via the beam splitter 108 and the relay optical system 104, and the target focused point group P described above is formed on the two-dimensional image sensor 106. The original target image IP1 described above is a two-dimensional image generated by the two-dimensional image sensor 106 at this time. 【0083】 If the object to be inspected 2 is not placed between the beam splitter 108 and the plane mirror 109, the wavefront-free light L reflected by the plane mirror 109, i.e., the reference light LQ described above, is incident on the microlens array 105 via the beam splitter 108 and the relay optical system 104, and the reference focused point group Q described above is formed on the two-dimensional image sensor 106. The original reference image IQ1 described above is a two-dimensional image generated by the two-dimensional image sensor 106 at this time. 【0084】 The arithmetic unit 107 is configured to measure the wavefront aberration of the target light LP by referring to the original target image IP1 and the original reference image IQ1 generated by the two-dimensional image sensor 106. The arithmetic unit 1 described above is used as the arithmetic unit 107. The arithmetic unit 107 calculates the wavefront aberration amount (e.g., Zernike coefficient) representing the wavefront aberration of the target light LP by performing the calculation method S1 described above. 【0085】 In Figure 9, a concave lens is shown as the object to be inspected 2, but this is not the only example. For example, a convex lens may also be used as the object to be inspected 2. Any optical element that transmits light, or any combination thereof, can be used as the object to be inspected 2. 【0086】 [Modified example of wavefront sensor 3] A third modified example of the wavefront sensor 100 described above (hereinafter referred to as wavefront sensor 100C) will be explained with reference to Figure 10. Figure 10 is a block diagram showing the main components of wavefront sensor 100C. 【0087】 The wavefront sensor 100C is an ophthalmic wavefront sensor for measuring the refractive state and optical wavefront aberration of the human eye 3. The wavefront sensor 100C is a modified version of the wavefront sensor 100 described above, with the beam expander 103 omitted and a beam splitter 108 added. 【0088】 The collimating lens 102 and the beam splitter 108 are arranged in this order along the optical path of the light L output from the measuring light source 101. The light L emitted from the collimating lens 102 and transmitted through the beam splitter 108 enters the eye 3 through the pupil. The light L that enters the eye 3 passes through intermediate transparent materials such as the cornea, lens, and vitreous humor and is scattered and reflected on the retina. As a result, each point on the retina becomes a secondary point light source. The light L emitted from each point on the retina passes through the intermediate transparent materials again and is emitted from the eye 3 through the pupil. The relay optical system 104, the microlens array 105, and the two-dimensional image sensor 106 are arranged in this order along the optical path of the light L that has been emitted from the eye 3 and reflected by the beam splitter 108. 【0089】 When the eye 3 is placed in the optical path of the light L that has passed through the beam splitter 108, the wavefront aberrated light L that originates from each point on the retina and passes through the intermediate transparent material, i.e., the target light LP described above, is incident on the microlens array 105 via the beam splitter 108 and the relay optical system 104, and the target concentrated point group P described above is formed on the two-dimensional image sensor 106. The original target image IP1 described above is a two-dimensional image generated by the two-dimensional image sensor 106 at this time. 【0090】 When a test optical system that reflects aberration-free plane waves is placed in place of eye 3 on the optical path of light L transmitted through beam splitter 108, the wavefront aberration-free light L reflected by the optical system, i.e., the reference light LQ described above, is incident on the microlens array 105 via beam splitter 108 and relay optical system 104, and the reference focused point group Q described above is formed on the two-dimensional image sensor 106. The original reference image IQ1 described above is a two-dimensional image generated by the two-dimensional image sensor 106 at this time. 【0091】 The arithmetic unit 107 is configured to measure the wavefront aberration of the target light LP by referring to the original target image IP1 and the original reference image IQ1 generated by the two-dimensional image sensor 106. The arithmetic unit 1 described above is used as the arithmetic unit 107. The arithmetic unit 107 calculates the wavefront aberration amount (e.g., Zernike coefficient) representing the wavefront aberration of the target light LP by performing the calculation method S1 described above. 【0092】 The refractive state of the human eye varies, and the components of wavefront aberration measured are predominantly defocus and astigmatism. The amount of defocus corresponds to the degree of myopia or hyperopia, and the amount of astigmatism corresponds to the degree of astigmatism. With the wavefront sensor 100C, even with myopia, hyperopia, and astigmatism, which vary greatly from person to person, measurements can be taken over a very wide range without the need for optical system correction. 【0093】 [Example of wavefront sensor operation] An example of the operation of the wavefront sensor 100 described above will be explained with reference to Figures 11 to 15. 【0094】 Figure 11 shows the original reference image IQ1 acquired by the wavefront sensor 100 through the reference image acquisition process S11b, inverted in black and white, when the object to be inspected 2 is not placed. 【0095】 As shown in Figure 11, the arrangement of the reference focal point group Q in the original reference image IQ1 is approximated by the arrangement of the grid point group of the reference grid XQ. The grid vectors W1 and W2 of the reference grid XQ are shown in the enlarged view (right side) of the vicinity of the center of the original reference image IQ1. Also, each reference focal point q belonging to the reference focal point group Q is shown. i The assigned grid coordinates (m,n) are shown in the enlarged view (lower side) of the area around the center of the original reference image IQ1. 【0096】 Figure 12(a) shows the original target image IP1 acquired by the wavefront sensor 100 through the target image acquisition process S11a when the object to be inspected 2 is placed, with the colors inverted. Figure 12(b) shows the simplified target image IP2 generated by the wavefront sensor 100 through the target image simplification process S13, with the colors inverted. 【0097】 As shown in Figures 12(a) and 12(b), the arrangement of the target condensing point cloud P in the original target image IP1 and the simplified target image IP2 is approximated by the arrangement of the grid point cloud of the target grid XP. 【0098】 In addition, in the original target image IP1 and the simplified target image IP2, the target light-gathering point p is located in the peripheral region. i It can be seen from Figures 12(a) and 12(b) that it does not exist. This is because the aperture is restricted in the wavefront sensor 100. Also, in the simplified target image IP2, the target focusing point p i Figure 12(b) shows that there are missing areas where the light is absent. This is because the low-luminance target focal point p i This is because it may not be detected in the target light-gathering point detection process S12a. 【0099】 Figure 13 shows the reciprocal lattice image IR generated by the wavefront sensor 100 through the Fourier transform process S14, with the colors inverted. 【0100】 As shown in Figure 13, in the reciprocal lattice image IR, the target focal point p is located in the simplified image IP2. i Even if there are missing areas where no data points exist, a reciprocal lattice IR without missing data points is constructed. The lattice vectors U1 and U2 of the reciprocal lattice XR obtained by the reciprocal lattice vector derivation process S15 are shown in an enlarged view of the vicinity of the center of the reciprocal lattice image IR. 【0101】 Figure 14(a) shows the grid point p' of the target grid XP estimated by the wavefront sensor 100 through the target grid estimation process S16. mn Figure 14(b) shows a diagram in which (white rectangles) are drawn on the simplified target image IP2 shown in Figure 12(b). i This figure shows the grid coordinates (m,n) assigned to the element drawn on the simplified image IP2 shown in Figure 12(b). 【0102】 As shown in Figure 14(b), the simplified image IP2 has a target focusing point p iEven if there are missing locations where data is not present, it can be seen that each target focal point pi belonging to the target focal point group P is correctly assigned lattice coordinates (m,n). 【0103】 Figure 15(a) shows the result of the focusing point pairing process S17 when the target light LP is defocused (when the convex lens is the object to be inspected 2). In Figure 15(a), each reference focusing point q belonging to the reference focusing point group Q i These are shown as black rectangles, and each target condensation point p belonging to the target condensation point group P i This is shown as a black circle, and the paired reference focal point q i and target focal point p i The points are shown connected by a dashed line. The reference focal point q is denoted by the grid coordinates (0,0). i The reference focal point q is the point closest to the optical center. i The reference focusing point is q. i and target focal point p i It can be seen that they are correctly paired. 【0104】 Figure 15(b) shows the results of the focusing point pairing process S17 when the target light LP has astigmatism (when a cylindrical lens is the object to be inspected 2). In Figure 15(b), each reference focusing point q belonging to the reference focusing point group Q i These are shown as black rectangles, and each target condensation point p belonging to the target condensation point group P i This is shown as a black circle, and the paired reference focal point q i and target focal point p i The points are shown connected by a dashed line. The reference focal point q is denoted by the grid coordinates (0,0). i The reference focal point q is the point closest to the optical center. i This is the case even if the lattice vectors V1 and V2 of the target lattice XR are not orthogonal to each other, the reference focal point q i and target focal point p i It can be seen that they are correctly paired. 【0105】 〔summary〕 (Aspect 1) A reference focal point detection process that detects each reference focal point belonging to the reference focal point group by referring to a reference image representing a reference focal point group formed by applying a microlens array to a reference light, A target focal point detection process that detects each target focal point belonging to the target focal point group by referring to a target image representing a target focal point group formed by applying the microlens array to the target light, A Fourier transform process that generates a reciprocal lattice image representing a reciprocal lattice point cloud by performing a two-dimensional Fourier transform on the aforementioned target image, A reciprocal lattice vector derivation process is performed to derive the lattice vector of the reciprocal lattice by referring to the reciprocal lattice image generated by the Fourier transform process, A target grid estimation process is performed to estimate a target grid whose arrangement of grid points approximates the arrangement of the target light-gathering point cloud, by referring to the grid vector of the reciprocal grid derived in the reciprocal grid vector derivation process, (a) Assigning to each target focal point detected in the target focal point detection process the grid coordinates of the grid points of the target grid estimated in the target grid estimation process that are closest to the target focal point; (b) Assigning to each reference focal point detected in the reference focal point detection process the grid coordinates of the grid points of the reference grid whose grid point arrangement approximates the arrangement of the reference focal point group that are closest to the reference focal point; (c) Focus point pairing, which pairs the target focal point and the reference focal point to which the same grid coordinates are assigned; For each pair paired in the aforementioned focusing point pairing, a focusing point movement amount derivation process is performed to derive the amount of movement from the reference focusing point constituting the pair to the target focusing point constituting the pair, A wavefront aberration amount derivation process is performed, which derives a wavefront aberration amount representing the wavefront aberration of the target light by referring to each movement amount derived in the aforementioned focusing point movement amount derivation process. A computing device characterized by the following features. 【0106】 (Aspect 2) When the target light is applied to the microlens array to form the target light-gathering point cloud on the two-dimensional image sensor, a target image simplification process is further performed to generate a simplified target image by simplifying the original target image generated by the two-dimensional image sensor. The target image referenced in the Fourier transform process is the simplified target image generated in the target image simplification process. The computing device according to embodiment 1, characterized in that 【0107】 (Aspect 3) In the aforementioned target grid estimation process, (a) referencing the grid vectors U1 and U2 of the reciprocal grid, the grid vectors V1 and V2 of the target grid are derived according to equations (1) and (2) below using the matrix R defined by equation (3) below, and (b) referencing the grid vectors V1 and V2 of the target grid, the grid point p' of the target grid is determined according to equation (4) below. mn Derive the following: The arithmetic device according to embodiment 1 or 2, characterized by the features described herein. 【number】 【number】 【number】 【number】 【0108】 (Aspect 4) A reference focal point detection process that detects each reference focal point belonging to the reference focal point group by referring to a reference image representing a reference focal point group formed by applying the microlens array to a reference light, A target focal point detection process that detects each target focal point belonging to the target focal point group by referring to a target image representing a target focal point group formed by applying the microlens array to the target light, A Fourier transform process that generates a reciprocal lattice image representing a reciprocal lattice point cloud by performing a two-dimensional Fourier transform on the aforementioned target image, A reciprocal lattice vector derivation process is performed to derive the lattice vector of the reciprocal lattice by referring to the reciprocal lattice image generated by the Fourier transform process, A target grid estimation process is performed to estimate a target grid whose arrangement of grid points approximates the arrangement of the target light-gathering point cloud, by referring to the grid vector of the reciprocal grid derived in the reciprocal grid vector derivation process, (a) Assigning to each target focal point detected in the target focal point detection process the grid coordinates of the grid points of the target grid estimated in the target grid estimation process that are closest to the target focal point; (b) Assigning to each reference focal point detected in the reference focal point detection process the grid coordinates of the grid points of the reference grid whose grid point arrangement approximates the arrangement of the reference focal point group that are closest to the reference focal point; (c) Focus point pairing, which pairs the target focal point and the reference focal point to which the same grid coordinates are assigned; For each pair paired in the aforementioned focusing point pairing, a focusing point movement amount derivation process is performed to derive the amount of movement from the reference focusing point constituting the pair to the target focusing point constituting the pair, The process includes a wavefront aberration amount derivation process that derives a wavefront aberration amount representing the wavefront aberration of the target light by referring to each movement amount derived in the aforementioned focusing point movement amount derivation process. A calculation method characterized by the following. 【0109】 (Appendix 5) At least one processor, A reference focal point detection process that detects each reference focal point belonging to the reference focal point group by referring to a reference image representing a reference focal point group formed by applying a microlens array to a reference light, A target focal point detection process that detects each target focal point belonging to the target focal point group by referring to a target image representing a target focal point group formed by applying the microlens array to the target light, A Fourier transform process that generates a reciprocal lattice image representing a reciprocal lattice point cloud by performing a two-dimensional Fourier transform on the aforementioned target image, A reciprocal lattice vector derivation process is performed to derive the lattice vector of the reciprocal lattice by referring to the reciprocal lattice image generated by the Fourier transform process, A target grid estimation process is performed to estimate a target grid whose arrangement of grid points approximates the arrangement of the target light-gathering point cloud, by referring to the grid vector of the reciprocal grid derived in the reciprocal grid vector derivation process, (a) Assigning to each target focal point detected in the target focal point detection process the grid coordinates of the grid points of the target grid estimated in the target grid estimation process that are closest to the target focal point; (b) Assigning to each reference focal point detected in the reference focal point detection process the grid coordinates of the grid points of the reference grid whose grid point arrangement approximates the arrangement of the reference focal point group that are closest to the reference focal point; (c) Focus point pairing, which pairs the target focal point and the reference focal point to which the same grid coordinates are assigned; For each pair paired in the aforementioned focusing point pairing, a focusing point movement amount derivation process is performed to derive the amount of movement from the reference focusing point constituting the pair to the target focusing point constituting the pair, The process involves deriving a wavefront aberration amount that represents the wavefront aberration of the target light by referring to each movement amount derived in the aforementioned focusing point movement amount derivation process. A calculation program characterized by the following features. 【0110】 (Aspect 6) A computing device as described in any one of embodiments 1 to 3, The aforementioned microlens array, A two-dimensional image sensor for generating the aforementioned target image and the aforementioned reference image, A wavefront sensor characterized by having the following features. 【0111】 [Additional Notes] This disclosure includes the technologies described in the following appendices. However, this disclosure is not limited to the technologies described in the following appendices and is subject to various modifications. [Explanation of symbols] 【0112】 1 Computing device 11 memory 12 processors 13 Storage Wavefront sensors: 100, 100A, 100B, 100C 101 Measurement light source 102 Collimating Lens 103 Beam Expander 104 Relay Optics 105 Microlens Array 106 2D Image Sensor 107 Arithmetic equipment 108 Beam Splitter 109 Plane mirror 2. Items to be inspected 3 eyes

Claims

[Claim 1] A reference focal point detection process that detects each reference focal point belonging to the reference focal point group by referring to a reference image representing a reference focal point group formed by applying a microlens array to a reference light, A target focal point detection process that detects each target focal point belonging to the target focal point group by referring to a target image representing a target focal point group formed by applying the microlens array to the target light, A Fourier transform process that generates a reciprocal lattice image representing a reciprocal lattice point cloud by performing a two-dimensional Fourier transform on the aforementioned target image, A reciprocal lattice vector derivation process is performed to derive the lattice vector of the reciprocal lattice by referring to the reciprocal lattice image generated by the Fourier transform process, A target grid estimation process is performed to estimate a target grid whose arrangement of grid points approximates the arrangement of the target light-gathering point cloud, by referring to the grid vector of the reciprocal grid derived in the reciprocal grid vector derivation process, (a) Assigning to each target focal point detected in the target focal point detection process the grid coordinates of the grid points of the target grid estimated in the target grid estimation process that are closest to the target focal point; (b) Assigning to each reference focal point detected in the reference focal point detection process the grid coordinates of the grid points of the reference grid whose grid point arrangement approximates the arrangement of the reference focal point group that are closest to the reference focal point; (c) Focus point pairing, which pairs the target focal point and the reference focal point to which the same grid coordinates have been assigned; For each pair paired in the aforementioned focusing point pairing, a focusing point movement amount derivation process is performed to derive the amount of movement from the reference focusing point constituting the pair to the target focusing point constituting the pair, A wavefront aberration amount derivation process is performed, which derives a wavefront aberration amount representing the wavefront aberration of the target light by referring to each movement amount derived in the aforementioned focusing point movement amount derivation process. A computing device characterized by the following features. [Claim 2] When the target light is applied to the microlens array to form the target focused point cloud on the two-dimensional image sensor, a target image simplification process is further performed to generate a simplified target image by simplifying the original target image generated by the two-dimensional image sensor. The target image referenced in the Fourier transform process is the simplified target image generated in the target image simplification process. The computing device according to feature 1. [Claim 3] In the aforementioned target grid estimation process, (a) the grid vector U of the reciprocal grid １ , U ２ Referring to the following equation (3), the grid vector V of the target grid is calculated using the matrix R defined by equation (1) and equation (2) below. １ , V ２ (b) Derive the lattice vector V of the target lattice. １ , V ２ Referring to the following equation (4), the grid point p' of the target grid is determined. ｍｎ Derive the following: The computing device according to feature 1. [Math 1] [Math 2] [Math 3] [Math 4] [Claim 4] A reference focal point detection process that detects each reference focal point belonging to the reference focal point group by referring to a reference image representing a reference focal point group formed by applying a microlens array to a reference light, A target focal point detection process that detects each target focal point belonging to the target focal point group by referring to a target image representing a target focal point group formed by applying the microlens array to the target light, A Fourier transform process that generates a reciprocal lattice image representing a reciprocal lattice point cloud by performing a two-dimensional Fourier transform on the aforementioned target image, A reciprocal lattice vector derivation process is performed to derive the lattice vector of the reciprocal lattice by referring to the reciprocal lattice image generated by the Fourier transform process, A target grid estimation process is performed to estimate a target grid whose arrangement of grid points approximates the arrangement of the target light-gathering point cloud, by referring to the grid vector of the reciprocal grid derived in the reciprocal grid vector derivation process, (a) Assigning to each target focal point detected in the target focal point detection process the grid coordinates of the grid points of the target grid estimated in the target grid estimation process that are closest to the target focal point; (b) Assigning to each reference focal point detected in the reference focal point detection process the grid coordinates of the grid points of the reference grid whose grid point arrangement approximates the arrangement of the reference focal point group that are closest to the reference focal point; (c) Focus point pairing, which pairs the target focal point and the reference focal point to which the same grid coordinates have been assigned; For each pair paired in the aforementioned focusing point pairing, a focusing point movement amount derivation process is performed to derive the amount of movement from the reference focusing point constituting the pair to the target focusing point constituting the pair, The process includes a wavefront aberration amount derivation process that derives a wavefront aberration amount representing the wavefront aberration of the target light by referring to each movement amount derived in the aforementioned focusing point movement amount derivation process. A calculation method characterized by the following. [Claim 5] At least one processor, A reference focal point detection process that detects each reference focal point belonging to the reference focal point group by referring to a reference image representing a reference focal point group formed by applying a microlens array to a reference light, A target focal point detection process that detects each target focal point belonging to the target focal point group by referring to a target image representing a target focal point group formed by applying the microlens array to the target light, A Fourier transform process that generates a reciprocal lattice image representing a reciprocal lattice point cloud by performing a two-dimensional Fourier transform on the aforementioned target image, A reciprocal lattice vector derivation process is performed to derive the lattice vector of the reciprocal lattice by referring to the reciprocal lattice image generated by the Fourier transform process, A target grid estimation process is performed to estimate a target grid whose arrangement of grid points approximates the arrangement of the target light-gathering point cloud, by referring to the grid vector of the reciprocal grid derived in the reciprocal grid vector derivation process, (a) Assigning to each target focal point detected in the target focal point detection process the grid coordinates of the grid points of the target grid estimated in the target grid estimation process that are closest to the target focal point; (b) Assigning to each reference focal point detected in the reference focal point detection process the grid coordinates of the grid points of the reference grid whose grid point arrangement approximates the arrangement of the reference focal point group that are closest to the reference focal point; (c) Focus point pairing, which pairs the target focal point and the reference focal point to which the same grid coordinates have been assigned; For each pair paired in the aforementioned focusing point pairing, a focusing point movement amount derivation process is performed to derive the amount of movement from the reference focusing point constituting the pair to the target focusing point constituting the pair, The process involves deriving a wavefront aberration amount that represents the wavefront aberration of the target light by referring to each movement amount derived in the aforementioned focusing point movement amount derivation process. A calculation program characterized by the following features. [Claim 6] A computing device according to any one of claims 1 to 3, The aforementioned microlens array, A two-dimensional image sensor for generating the aforementioned target image and the aforementioned reference image, A wavefront sensor characterized by having the following features.

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