Image acquisition device and image acquisition method

Abstract

To provide a device and a method, capable of acquiring an image of an object of which an error is reduced by a ghost imaging.SOLUTION: An image acquisition device 1 comprises: a light source 11; a space light modulator 13; an optical detector 15; and a control part 18. The control part 18 sequentially sets a pattern of an optical spatial strength modulation by the space light modulator 13 to M different patterns, acquires a light strength detected by the optical detector 15 in a period to be set to each of the M patterns, and calculates an image of an object by a ghost imaging on the basis of the light strength and the M patterns. The control part 18 removes a W as one component contained in an image X of the object from X to perform the ghost imaging, and calculates an image (X-W) of an object obtained by removing the W from X.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an apparatus and a method for acquiring an image of an object by ghost imaging.

Background Art

[0002] Non-Patent Document 1 describes a technique for acquiring an image of an object by ghost imaging. The ghost imaging technique arranges a spatial light modulator and an object between a light source and a photodetector, sequentially sets the pattern of the spatial intensity modulation of light by the spatial light modulator to each of M different patterns, acquires the light intensity detected by the photodetector during the period set for each of the M patterns, and obtains the image of the object based on the correlation operation of each pattern and each light intensity.

[0003] The photodetector used in the ghost imaging technique may be a single-pixel photodetector (point sensor). Therefore, even in a wavelength range where it is difficult to acquire a two-dimensional image using an area sensor in which a plurality of pixels are two-dimensionally arranged, if there is a point sensor having light reception sensitivity in that wavelength range, a two-dimensional image of the object can be acquired by ghost imaging using that point sensor.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In ghost imaging technology, when performing the correlation operation of each pattern and each light intensity, an orthogonal matrix approximation is performed. Therefore, even in an ideal situation without shot noise, with a finite number of patterns M, the image of the object cannot be completely reconstructed. Non-Patent Document 2 describes that when the column vector with each pixel value of the image of the object as an element is X, the error (variance) due to the orthogonal matrix approximation is approximately represented by the following formula (1). That is, the image X of the object obtained by ghost imaging contains an error proportional to the sum of the squares of each pixel value of the image X.

[0006]

Number

[0007] The present invention has been made to solve the above problems, and an object thereof is to provide an apparatus and a method capable of obtaining an image of an object with reduced error by ghost imaging.

Means for Solving the Problems

[0008] The image acquisition device of the present invention includes: (1) a light source that outputs light; (2) a photodetector that detects the intensity of the light output from the light source and passing through the object; (3) a spatial light modulator provided on the optical path between the light source and the photodetector and spatially modulating the light; and (4) a control unit that sequentially sets the patterns of the spatial intensity modulation of the light by the spatial light modulator to M different patterns respectively, acquires the light intensity detected by the photodetector during the period set for each of the M patterns, and obtains an image of the object by ghost imaging based on these light intensities and the M patterns.

[0009] In the first aspect of the image acquisition device of the present invention, the control unit represents the AC component of the column vector X, where the value of the n-th region (n = 1 to N) of the image of the object is the n-th element x n as the sum of a first AC component and a second AC component that are orthogonal to each other. When the AC component of the column vector W, which is a part of the components included in this column vector X, includes only the second AC component among the first AC component and the second AC component, at the m-th pattern (m = 1 to M) among the M patterns, the value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the image of the object is the element a m,n at the m-th row and n-th column of the system matrix A. Based on the system matrix A in which all the elements of the column vector of the product of A and W are equal to each other, the spatial intensity modulation pattern of the light by the spatial light modulator is sequentially set to each of the M patterns, and the light intensity y m detected by the photodetector when the m-th pattern is set is acquired, and based on y1 to y M and a 1,1 ~a M,N , an image of the object excluding the column vector W from the column vector X is obtained.

[0010] In the second aspect of the image acquisition device of the present invention, the control unit represents the value of the n-th region (n = 1 to N) of the image of the object as the n-th element x nLet the column vector X to be considered contain an AC component and a DC component, and when the column vector W, which is a part of the components contained in this column vector X, contains only the DC component, a value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the image of the object in the m-th pattern (m = 1 to M) out of the M patterns is the element a in the m-th row and n-th column. m,n A system matrix A is defined such that the sum of the elements in each row is equal to each other. Based on this system matrix A, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set for each of the M patterns, and the light intensity y detected by the photodetector when the m-th pattern is set. m is obtained, and based on y1 to y M and a 1,1 to a M,N the image of the object with the column vector W excluded from the column vector X is obtained.

[0011] In the third aspect of the image acquisition device of the present invention, the control unit sets the value of the n-th region (n = 1 to N) of the image of the object as the n-th element x n of the column vector X. The AC component of the column vector X is represented as the sum of a first AC component and a second AC component that are orthogonal to each other, and when the AC component of the column vector W, which is a part of the components contained in this column vector X, contains only the second AC component out of the first AC component and the second AC component, a value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the image of the object in the m-th pattern (m = 1 to M) out of the M patterns is the element a m,n of the system matrix A. Based on this system matrix A, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set for each of the M patterns, and the light intensity y detected by the photodetector when the m-th pattern is set. m is obtained, and the sum of the product of the n-th element w n of W and a m,n with respect to n is defined as α m , and y' m = y m / α m is defined, and a' m,n = a m,n / α m is defined. Then, based on y'1 to y' M and a' 1,1 to a' M,NBased on this, an image of the object with the column vector W excluded from the column vector X is obtained.

[0012] In the fourth aspect of the image acquisition apparatus of the present invention, the control unit sets the value of the n-th region (n = 1 to N) of the image of the object as the n-th element x n When the column vector X, which is a column vector with the AC component and the DC component, and the column vector W, which is a part of the components included in this column vector X, contains only the DC component, the value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the object image in the m-th pattern (m = 1 to M) among the M patterns is the element a in the m-th row and n-th column m,n Based on the system matrix A, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set for each of the M patterns, and the light intensity y m detected by the photodetector when the m-th pattern is set is acquired, and the sum of the products of the n-th element w n of W and a m,n for n is defined as α m Let y' m = y m / α m Let a' m,n = a m,n / α m Based on y'1 to y' M and a' 1,1 to a' M,N an image of the object with the column vector W excluded from the column vector X is obtained.

[0013] In the fifth aspect of the image acquisition apparatus of the present invention, the control unit sets the value of the n-th region (n = 1 to N) of the image of the object as the n-th element x n When the AC component of the column vector X is represented as the sum of the first AC component and the second AC component that are orthogonal to each other, and the AC component of the column vector W, which is a part of the components included in this column vector X, contains only the second AC component among the first AC component and the second AC component, the value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the object image in the m-th pattern (m = 1 to M) among the M patterns is the element a in the m-th row and n-th column m,nBased on the system matrix A to be set, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set for each of the M patterns, and the light intensity y detected by the photodetector when the m-th pattern is set m is obtained, and the sum of the products of the n-th element w of W n and a m,n for n is defined as α m , and y' m = y m - α m is set. Based on y'1 to y' M and a 1,1 to a M,N , an image of the object with the column vector W excluded from the column vector X is obtained.

[0014] In the sixth aspect of the image acquisition device of the present invention, for the control unit, when the column vector X in which the values of the n-th region (n = 1 to N) of the image of the object are the n-th element x n includes an AC component and a DC component, and the column vector W, which is a part of the components included in this column vector X, includes only the DC component, for the m-th pattern (m = 1 to M) among the M patterns, the value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the image of the object is the element a at the m-th row and n-th column m,n Based on the system matrix A to be set, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set for each of the M patterns, and the light intensity y detected by the photodetector when the m-th pattern is set m is obtained, and the sum of the products of the n-th element w of W n and a m,n for n is defined as α m , and y' m = y m - α m is set. Based on y'1 to y' M and a 1,1 to a M,N , an image of the object with the column vector W excluded from the column vector X is obtained.

[0015] In the seventh aspect of the image acquisition device of the present invention, for the control unit, when the values of the n-th region (n = 1 to N) of the image of the object are the n-th element x nThe AC component of the column vector X, which is set as such, is represented as the sum of a first AC component and a second AC component that are orthogonal to each other. When the AC component of the column vector W, which is a part of the components included in this column vector X, includes only the second AC component out of the first AC component and the second AC component, a value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the image of the object in the m-th pattern (m = 1 to M) among the M patterns is the element a in the m-th row and n-th column m,n Based on the system matrix A, which is set as such, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set for each of the M patterns, and the light intensity y detected by the photodetector when the m-th pattern is set m is acquired, and the sum of a m,n for n is defined as β m and the value obtained by dividing the sum of the product of the n-th element x n,AC2 of the second AC component and a m,n by β m is defined as γ m and y' m = y m / β m - γ m is defined as such, and a' m,n = a m,n / β m is defined as such. Based on y'1 to y' M and a' 1,1 to a' M,N , an image of the object excluding the column vector W from the column vector X is obtained.

[0016] In the eighth aspect of the image acquisition device of the present invention, in addition to any one of the first to seventh aspects, the control unit adds all or part of the column vector W to the image of the object obtained by excluding the column vector W from the column vector X.

[0017] In the ninth aspect of the image acquisition device of the present invention, in addition to any one of the first to eighth aspects, the control unit multiplies a value corresponding to the product of the intensity modulation amount in the region corresponding to the n-th region of the image of the object in the m-th pattern and the light intensity in the n-th region of the object when the light output from the light source reaches the object without passing through the spatial light modulator, by the element a in the m-th row and n-th column of the system matrix A m,n and sets it as such.

[0018] The image acquisition method of the present invention uses a light source that outputs light, a photodetector that detects the intensity of the light output from the light source and passing through the object, and a spatial light modulator that is provided on the optical path between the light source and the photodetector and spatially modulates the light intensity. The method sequentially sets the patterns of the spatial intensity modulation of the light by the spatial light modulator to M different patterns respectively, acquires the light intensity detected by the photodetector during the period set for each of the M patterns, and obtains the image of the object by ghost imaging based on these light intensities and the M patterns.

[0019] In the first aspect of the image acquisition method of the present invention, the AC components of the column vector X, where the value of the n-th region (n = 1 to N) of the image of the object is the n-th element x n are represented as the sum of a first AC component and a second AC component that are orthogonal to each other. When the AC component of the column vector W, which is a part of the components included in this column vector X, includes only the second AC component among the first AC component and the second AC component, at the m-th pattern (m = 1 to M) of the M patterns, the value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the image of the object is the element a m,n in the m-th row and n-th column. Based on the system matrix A, where all the elements of the column vector of the product of A and W are equal to each other, the spatial intensity modulation pattern of the light by the spatial light modulator is sequentially set to each of the M patterns, and the light intensity y m detected by the photodetector when the m-th pattern is set is acquired. Based on y1 to y M and a 1,1 ~a M,N , the image of the object excluding the column vector W from the column vector X is obtained.

[0020] In the second aspect of the image acquisition method of the present invention, the value of the n-th region (n = 1 to N) of the image of the object is the n-th element x nLet the column vector X include an AC component and a DC component, and when the column vector W, which is a part of the components included in this column vector X, includes only the DC component, a value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the image of the object in the m-th pattern (m = 1 to M) out of the M patterns is the element a in the m-th row and n-th column m,n A system matrix A as described above, based on the system matrix A in which the sum of the elements in each row is equal to each other, sequentially sets the spatial intensity modulation pattern of light by the spatial light modulator for each of the M patterns, and the light intensity y detected by the photodetector when the m-th pattern is set m is obtained, and based on y1 to y M and a 1,1 ~a M,N the image of the object excluding the column vector W from the column vector X is obtained

[0021] In the third aspect of the image acquisition method of the present invention, the value of the n-th region (n = 1 to N) among the N regions of the image of the object is the n-th element x n of the column vector X, and the AC component of the column vector X is represented as the sum of a first AC component and a second AC component that are orthogonal to each other. When the AC component of the column vector W, which is a part of the components included in this column vector X, includes only the second AC component among the first AC component and the second AC component, a value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the image of the object in the m-th pattern (m = 1 to M) out of the M patterns is the element a m,n of the system matrix A as described above. Based on the system matrix A, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set for each of the M patterns, and the light intensity y detected by the photodetector when the m-th pattern is set m is obtained, and the sum of the product of the n-th element w n of W and a m,n is defined as α m , y' m =y m / α m is defined, a' m,n =a m,n / α m is defined, and based on y'1 to y' M and a' 1,1 ~a' M,NBased on this, an image of the object from which the column vector W is excluded from the column vector X is obtained.

[0022] In the fourth aspect of the image acquisition method of the present invention, among the N regions of the image of the object, the value of the n-th region (n = 1 to N) is the n-th element x n of the column vector X that includes an AC component and a DC component, and when the column vector W, which is a part of the components included in this column vector X, includes only the DC component, a value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the image of the object in the m-th pattern (m = 1 to M) among the M patterns is the element a m,n in the m-th row and n-th column of the system matrix A. Based on this, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set for each of the M patterns, and the light intensity y m detected by the photodetector when the m-th pattern is set is acquired. The sum of the products of the n-th element w n of W and a m,n for n is defined as α m , and y' m = y m / α m is defined, and a' m,n = a m,n / α m is defined. Based on y'1 to y' M and a' 1,1 to a' M,N , an image of the object from which the column vector W is excluded from the column vector X is obtained.

[0023] In the fifth aspect of the image acquisition method of the present invention, among the N regions of the image of the object, the value of the n-th region (n = 1 to N) is the n-th element x n of the column vector X. The AC component of the column vector X is represented as the sum of a first AC component and a second AC component that are orthogonal to each other, and when the AC component of the column vector W, which is a part of the components included in this column vector X, includes only the second AC component among the first AC component and the second AC component, a value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the image of the object in the m-th pattern (m = 1 to M) among the M patterns is the element a m,nBased on the system matrix A to be set, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set for each of the M patterns, and the light intensity y detected by the photodetector at the time of setting the m-th pattern m is obtained, and the sum of the products of the n-th element w of W n and a m,n with respect to n is defined as α m and, with y' m =y m -α m as y'1 to y' M and a 1,1 ~a M,N Based on this, an image of the object with the column vector W excluded from the column vector X is obtained

[0024] In the sixth aspect of the image acquisition method of the present invention, the value of the n-th region (n = 1 to N) of the N regions of the image of the object is the n-th element x n of the column vector X that includes AC components and DC components, and when the column vector W, which is a part of the components included in this column vector X, includes only DC components, the intensity modulation amount in the region corresponding to the n-th region of the image of the object in the m-th pattern (m = 1 to M) of the M patterns is used as the element a in the m-th row and n-th column m,n Based on the system matrix A to be set, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set for each of the M patterns, and the light intensity y detected by the photodetector at the time of setting the m-th pattern m is obtained, and the sum of the products of the n-th element w of W n and a m,n with respect to n is defined as α m and, with y' m =y m -α m as y'1 to y' M and a 1,1 ~a M,N Based on this, an image of the object with the column vector W excluded from the column vector X is obtained

[0025] In the seventh aspect of the image acquisition method of the present invention, the value of the n-th region (n = 1 to N) of the N regions of the image of the object is the n-th element x nThe AC component of the column vector X to be used is represented as the sum of a first AC component and a second AC component that are orthogonal to each other. When the AC component of the column vector W, which is a part of the components included in this column vector X, includes only the second AC component out of the first AC component and the second AC component, a value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the image of the object in the m-th pattern (m = 1 to M) out of the M patterns is the element a in the m-th row and n-th column m,n Based on the system matrix A to be used, a spatial intensity modulation pattern of light by a spatial light modulator is sequentially set for each of the M patterns, and the light intensity y detected by a photodetector when the m-th pattern is set m is obtained, and the sum of a m,n for n is defined as β m ; a value obtained by dividing the sum for n of the product of the n-th element x n,AC2 of the second AC component and a m,n by β m is defined as γ m ; y' m = y m / β m - γ m ; a' m,n = a m,n / β m ; based on y'1 to y' M and a' 1,1 to a' M,N , an image of the object with the column vector W excluded from the column vector X is obtained.

[0026] In the eighth aspect of the image acquisition method of the present invention, in addition to any one of the first to seventh aspects, all or part of the column vector W is added to the image of the object obtained by excluding the column vector W from the column vector X.

[0027] In the ninth aspect of the image acquisition method of the present invention, in addition to any one of the first to eighth aspects, a value corresponding to the product of the intensity modulation amount in the region corresponding to the n-th region of the image of the object in the m-th pattern and the light intensity in the n-th region of the object when the light output from the light source reaches the object without passing through the spatial light modulator is set as the element a m,n in the m-th row and n-th column of the system matrix A.

Advantages of the Invention

[0028] According to the present invention, an image of an object with reduced error can be obtained by ghost imaging.

Brief Description of the Drawings

[0029]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Embodiments for Carrying Out the Invention

[0030] Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant descriptions are omitted. The present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope equivalent to the claims.

[0031] FIG. 1 is a diagram showing the configuration of an image acquisition device 1. The image acquisition device 1 includes a light source 11, an optical system 12, a spatial light modulator 13, an optical system 14, a photodetector 15, and a control unit 18, and obtains an image of an object 20 by ghost imaging. The light source 11 outputs light in a wavelength range in which the photodetector 15 has a light reception sensitivity. The photodetector 15 detects the intensity of the light output from the light source 11 and passing through the object 20. The photodetector 15 may be a single-pixel photodetector (point sensor). The spatial light modulator 13 is provided on the optical path between the light source 11 and the object 20, and spatially modulates the intensity of the light.

[0032] The control unit 18 sequentially sets the spatial intensity modulation patterns of the light by the spatial light modulator 13 to M different patterns respectively. The control unit 18 acquires the light intensity detected by the photodetector 15 during the period set for each of the M patterns. Then, the control unit 18 obtains an image of the object by ghost imaging based on these light intensities and the M patterns. The control unit 18 is, for example, a computer.

[0033] The optical systems 12 and 14 are provided as necessary. For example, the optical system 12 expands the beam diameter of the light output from the light source 11 and outputs the light with the expanded beam diameter to the spatial light modulator 13. The optical system 14 condenses the light that has reached through the object 20 and makes the light incident on the light receiving portion of the photodetector 15.

[0034] FIG. 2 is a diagram showing the configuration of the image acquisition device 2. Compared with the image acquisition device 1 (FIG. 1), the image acquisition device 2 (FIG. 2) is different in that the spatial light modulator 13 is provided. In the image acquisition device 2 (FIG. 2), the spatial light modulator 13 is provided on the optical path between the object 20 and the photodetector 15.

[0035] FIG. 3 is a diagram showing the configuration of the image acquisition device 3. Compared with the image acquisition device 1 (FIG. 1), the image acquisition device 3 (FIG. 3) is different in that it further includes a beam splitter 16 and an imaging unit 17. The setting of the pattern of the spatial intensity modulation of light by the spatial light modulator 13 may not be performed under the control of the control unit 18. For example, the spatial light modulator 13 may be a diffuser plate, and the pattern of the light irradiating the object 20 may be changed by moving the diffuser plate in a direction orthogonal to the light propagation direction. The beam splitter 16 is provided between the spatial light modulator 13 and the object 20, branches the light reaching from the spatial light modulator 13 into two, outputs one branched light to the object 20, and outputs the other branched light to the imaging unit 17. The imaging unit 17 receives the light reaching from the beam splitter 16, detects the spatial pattern of the light, and outputs a signal representing the detected pattern to the control unit 18. The control unit 18 obtains an image of the object by ghost imaging based on the pattern received from the imaging unit 17 and the light intensity received from the photodetector 15.

[0036] In addition to the configurations shown in FIGS. 1 to 3, various configurations are possible for the image acquisition device that obtains an image of an object by ghost imaging. The spatial light modulator may be a transmissive type or a reflective type. The reflective spatial light modulator may be a DMD (Digital Mirror Device). An image of the object may be acquired based on the light transmitted through the object, or an image of the object may be acquired based on the light reflected by the object.

[0037] In ghost imaging technology, the following column vector X, column vector Y, and system matrix A are considered.

[0038] The column vector X has, as its n-th element x, the value of the n-th region among N regions of the image of the object. n It is represented by the following equation (2). The column vector X has N elements x1 to x N representing the image of the object. In this specification, the column vector X may sometimes be referred to as the image X. N is an integer of 2 or more, and n is each integer from 1 to N.

[0039]

Number

[0040] The column vector Y has, as its m-th element y, the light intensity detected by the photodetector 15 when the m-th pattern among M patterns is set in the spatial light modulator 13. m It is represented by the following equation (3). The column vector Y has M elements y1 to y M representing the light intensity at the time of setting each pattern. M is an integer of 2 or more, and m is each integer from 1 to M.

[0041]

Number

[0042] The system matrix A is an M×N matrix representing the relationship between the column vector X and the column vector Y, and is represented by the following equation (4). The element a m,n at the m-th row and n-th column of the system matrix A is a value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the image of the object in the m-th pattern among the M patterns. Also, when the light intensity distribution in the object is not uniform when the light output from the light source reaches the object without passing through the spatial light modulator, the obtained column vector X (image X) may be divided by the light intensity distribution. Alternatively, the element a m,n at the m-th row and n-th column of the system matrix A may be a value corresponding to the product of the intensity modulation amount in the region corresponding to the n-th region of the image of the object in the m-th pattern and the light intensity in the n-th region of the object.

[0043]

Number

[0044] There is a relationship expressed by the following equation (5) among the column vector X, the column vector Y, and the system matrix A. In ghost imaging technology, the value of the n-th element x n of the column vector X (the value of the n-th region of the object's image) is estimated by the following equation (6). Thereby, the object's image X is reconstructed.

[0045]

Equation

[0046]

Equation

[0047] This equation (6) can be derived as follows. The column vector Y is converted into the column vector Z by the following equation (7), and the matrix A is converted into the matrix B by the following equation (8). I is the M×M identity matrix. J is the M×M matrix in which all element values are 1.

[0048]

Equation

[0049]

Equation

[0050] At this time, the following equation (9) holds. The least-squares solution of this equation (9) is given by the following equation (10). B t is the transpose matrix of the matrix B.

[0051]

Equation

[0052] [Mathematics]

[0053] When matrix B is approximated by an orthogonal matrix, the following approximate formula of formula (11) can be obtained. σ A 2 is the variance of the elements of matrix A. Using this approximation of formula (11), formula (10) becomes the following formula (12). Here, formula (13) is used. Writing formula (12) for each element results in formula (6) above.

[0054] [Mathematics]

[0055] [Mathematics]

[0056] [Mathematics]

[0057] Also, when the m-th pattern among the M patterns is represented by the column vector A of the following formula (14) m above, formulas (6) and (12) can also be expressed as follows:

[0058] [Mathematics]

[0059] [Mathematics]

[0060] Figure 4 is a flowchart for obtaining an image of an object by ghost imaging. In this flowchart, <ay>is the column vector A m and the light intensity y m the product A m y m represents the sum of, is the column vector A m represents the sum of, <y>represents the sum of the light intensities y m Here, the sum means the sum from m = 1 to m.

[0061] In step S11, the control unit 18 is m, <ay> 、< / ay> < / y> and <y>Perform each initialization. That is, set the pattern number m to 1, <ay> 、< / ay> < / y> and <y>Set each to 0.

[0062] In step S12, the control unit 18 sets the m-th pattern A m to the spatial light modulator 13, and obtains the light intensity y m detected by the photodetector 15 at that time.

[0063] In step S13, the control unit 18 <ay> 、< / ay> < / y> and <y>Perform each update to obtain the image X of the object. That is, <ay>Add A to m y m and use the result of the addition as the new <ay>shall be. < / ay> < / ay> < / y> Add A m to obtain a new addition result Let it be so. <y>to y m add them, and use the addition result as the new <y>Let it be so. And these updated <ay> 、< / ay> < / y> < / y> and <y>Using this, the image X of the object is calculated. The image X at this time corresponds to the sum from m = 1 to m on the right side of the above equation (15).

[0064] In step S14, the control unit 18 determines whether to end. For example, when an image X with sufficient image quality is obtained, or when a predetermined number of patterns M is reached, it ends. If it is determined in step S14 that the process has not ended yet, after the value of m is incremented by 1 in step S15, the process returns to step S12.

[0065] The control unit 18 repeats steps S12 and S13 while incrementing the value of m by 1 in step S15 until it determines to end in step S14. The value of m at the end point becomes the number of patterns M, and the image X at that time is represented by the above equation (15).

[0066] The image X of the object obtained in this way includes an error proportional to the sum of the squares of the pixel values of the image X (the values of the respective elements of the column vector X), as represented by the above equation (1). In the image acquisition apparatus and the image acquisition method of each embodiment described below, in order to reduce this error, ghost imaging is performed by excluding the column vector W, which is a part of the components included in the column vector X, from the column vector X, and an image (X - W) of the object from which W has been excluded from X is obtained. The column vector W to be excluded is known or can be obtained by other methods.

[0067] The column vector W to be excluded may be an unnecessary component in the image of the object, or may be an important component (or a part thereof) in the image of the object. In the latter case, all or part of W obtained by other methods may be added to the image (X - W) of the object obtained by excluding W. Unnecessary components in the image of the object are, for example, noise components and the DC component X DC is. Important components in the image of the object are, for example, the AC component X AC (or a part thereof).

[0068] The column vector (image of the object) X is the AC component X AC and the DC component X DC is represented by the sum with (the following equation (16)). The DC component X DC has equal values for all elements. The AC component X AC for each element x n,AC has a sum of 0 (the following equation (17)). In obtaining the image X of the object, the spatially varying AC component X DC is more important than the spatially uniform DC component X AC .

[0069]

Number

[0070]

Number

[0071] The DC component X DC for each element x n,DC when the value is c (the following equation (18)), since the sum of each element x n of the column vector X becomes cN (the following equation (19)), the value of c can be determined (the following equation (20)). The boldface "1" on the right side of equation (18) represents a column vector with all element values being 1. In this way, the DC component X DC of the column vector X can be determined, and also the AC component X AC of the column vector X can be determined. The AC component X AC and the DC component X DC are orthogonal to each other, and their inner product is 0 (the following equation (21)).

[0072]

Number

[0073]

Number

[0074] [Number]

[0075] [Number]

[0076] First, the first embodiment will be described. In the first embodiment, it is assumed that the column vector X is represented as the sum of a first AC component X AC1 , a second AC component X AC2 , and a DC component X DC (Equation (22) below). The column vector W to be excluded is assumed to be the sum of the second AC component X AC2 and the DC component X DC included in the column vector X (Equation (23) below). It is assumed that the first AC component X AC1 and the second AC component X AC2 are orthogonal to each other. That is, the value of the inner product between the first AC component X AC1 and the second AC component X AC2 is 0 (Equation (24) below).

[0077] [Number]

[0078] [Number]

[0079] [Number]

[0080] At this time, the system matrix A is designed such that all elements of the column vector of the product of the matrix A and the column vector W have equal values (Equation (25) below). The bold "1" on the right side of this equation represents a column vector in which all element values are 1.

[0081] [Number]

[0082] Based on the system matrix A designed in this way, the control unit 18 sequentially sets the pattern of spatial intensity modulation of light by the spatial light modulator 13 for each of the M patterns, and the light intensity y detected by the photodetector 15 when the m-th pattern is set. m is obtained. Then, based on the column vector Y and the system matrix A, the control unit 18 obtains the image X of the object with W excluded from X by the following equation (26) similar to the above equation (12). AC1 is obtained.

[0083]

Equation

[0084] The X obtained by this equation (26) AC1 is orthogonal to W, and the value of the inner product of W and X AC1 is 0 (the following equation (27)). That is, the obtained image X of the object AC1 is the one with W excluded from X.

[0085]

Equation

[0086] Next, the second embodiment will be described. In the second embodiment, it is assumed that the column vector X is represented by the sum of the AC component X AC and the DC component X DC (the following equation (28)). It is assumed that the column vector W to be excluded is only the DC component X DC included in the column vector X (the following equation (29)).

[0087]

Equation

[0088]

Equation

[0089] The second embodiment corresponds to a special case where the second AC component X in the first embodiment is set to 0. All elements of the column vector W are equal to each other (Equation (30) below). Therefore, the system matrix A may be designed such that the sum of the elements in each row of the matrix A is equal to each other. The system matrix A designed in this way satisfies the above Equation (25). AC2

[0090] [Number]

[0091] Based on the system matrix A designed in this way, the control unit 18 sequentially sets the pattern of the spatial intensity modulation of light by the spatial light modulator 13 for each of the M patterns, and the light intensity y detected by the photodetector 15 when the m-th pattern is set. m is obtained. Then, based on the column vector Y and the system matrix A, the control unit 18 obtains the image X of the object with W excluded from X by the following Equation (31), which is the same as Equation (12) above. AC

[0092] [Number]

[0093] Next, the third embodiment will be described. The third embodiment corresponds to an application example of the first embodiment. In the third embodiment, the column vector X is the sum of the first AC component X AC1 which is a component of the image originally desired to be obtained, and the first DC component X DC1 , as well as the second AC component X AC2 and the second DC component X DC2 , which are known unnecessary components (for example, noise components) (Equation (32) below). The column vector W to be excluded is the second AC component X AC2 included in the column vector X, the first DC component X DC1 and the second DC component X DC2 ​​is the sum of (the following equation (33)). The first AC component X AC1 and the second AC component X AC2 are assumed to be orthogonal to each other, and the value of the inner product of the first AC component X AC1 and the second AC component X AC2 is 0 (the above equation (24)).

[0094]

Number

[0095]

Number

[0096] The third embodiment corresponds to dividing the DC component X DC in the first embodiment into two, namely the first DC component X DC1 and the second DC component X DC2 . Therefore, also in the third embodiment, in the same manner as in the first embodiment, the image X AC1 of the object from which W is excluded can be obtained by the above equation (26).

[0097] In the third embodiment, since the sum of the first AC component X AC1 and the first DC component X DC1 is the component of the image that is originally desired to be obtained, it is necessary to also obtain the first DC component X DC1 . X DC1 can be obtained, for example, as follows. Light having a spatially uniform intensity distribution is incident on the object, and the intensity y DC of the light that has passed through the object is detected by the photodetector 15 (the following equation (34)). When the first DC component X DC1 is expressed by the following equation (35), equation (34) becomes as follows: equation (36). From this, the first DC component X DC1 is obtained (the following equation (37)).

[0098]

Number

[0099]

Number

[0100]

Number

[0101]

Number

[0102] In this way, the first AC component X AC1 and the first DC component X DC1 among them, the first AC component X AC1 is obtained as the image of the object excluding W from X (X - W), and the first DC component X DC1 is obtained from the light intensity y DC when light having a spatially uniform intensity distribution is incident on the object.

[0103] Next, the fourth embodiment will be described. The fourth embodiment corresponds to an application example of the first embodiment. In the fourth embodiment, the column vector X is, as in the first embodiment, the sum of the first AC component X AC1 the second AC component X AC2 and the DC component X DC (the following equation (38)). The way of dividing the AC component X AC into the first AC component X AC1 and the second AC component X AC2 is arbitrary. Once one is determined, the other is also determined, but these first AC component X AC1 and the second AC component X AC2 need to be orthogonal to each other (the above equation (24)).

[0104]

Number

[0105] For example, the image X' is obtained by the inverse matrix method with low resolution or camera measurement at different wavelengths, and X is represented by X' as shown in the following equation (39). By ghost imaging, the sum of this X and X is defined as W, and the image of the object excluding W from X (X - W) is obtained. Then, X is added to the image of the object to improve the image quality of the object. AC to obtain X as follows in equation (39): AC2 in terms of X' AC According to ghost imaging, the sum of this X AC2 and X DC is defined as W, and the image of the object excluding W from X (X - W) is obtained. Subsequently, X AC2 is added to the image of the object to improve the image quality of the object.

[0106]

Equation

[0107] However, this X' AC is not necessarily orthogonal to X AC1 . Therefore, a unit vector V AC is created from X' (using the following equation (40)). Using this, the above equation (38) becomes the following equation (41). It is necessary to set the coefficient a of the second term so that the first and second terms on the right side of equation (41) are orthogonal to each other. For this purpose, since the inner product of X (in equation (41)) and V AC2 is equal to a, a can be set as shown in the following equation (42). AC2 and V

[0108]

Equation

[0109]

Equation

[0110]

Equation

[0111] As a method for experimentally obtaining the value of a, there is the following first method. Irradiate the pattern represented by the following equation (43) and obtain the light intensity y0 represented by the following equation (44) at that time. The bold "1" on the right side of equation (43) represents a column vector in which the values of all elements are 1. Also, irradiate the pattern represented by a column vector in which the values of all elements are 1 and obtain the light intensity y1 represented by the following equation (45) at that time. Using these light intensities y0 and y1, the value of a can be obtained by the following equation (46).

[0112]

Number

[0113]

Number

[0114]

Number

[0115]

Number

[0116] As a method for experimentally obtaining the value of a, there is also the following second method. Obtain the image X TGI by the conventional ghost imaging technology, and the value of a may be obtained by the following equation (47) using this.

[0117]

Number

[0118] As a method for experimentally obtaining the value of a, there is also the following third method. Obtain an image excluding only the DC component as in the second embodiment, and as in the following equation (48), this image and V AC2 It suffices to take the inner product with it. Compared with the second method, the third method is more efficient because it requires fewer measurement times. Even if the image quality is poor, the inner product value can be obtained with good accuracy, so there is no need to acquire a high-quality image in advance.

[0119]

Number

[0120] The excluded column vector W is represented by the following equation (49). By performing ghost imaging after excluding W from X, the image X of the object from which W has been excluded from X is obtained. AC1 Then, the obtained image X of the object AC1 has the excluded X AC2 added to it (the following equation (50)). Alternatively, the excluded W is added to the image X of the object (the following equation (51)). By doing so, the image X of the object can be accurately reconstructed. AC1

[0121]

Number

[0122]

Number

[0123]

Number

[0124] The flowcharts for obtaining the images of the objects by ghost imaging in the first to fourth embodiments are the same as those in FIG. 4. However, in the first to fourth embodiments, the W to be excluded is determined in advance, and the system matrix A is set according to the W. Further, if necessary, all or part of the W obtained by other methods may be added to the image of the object from which W has been excluded from X.

[0125] Next, an example of the method for setting the system matrix A will be described. The first method and the second method described below are methods for setting the system matrix A when N = 4 for the sake of simplifying the explanation in the second embodiment. In the second embodiment, the system matrix A may be designed such that the sum of the elements in each row of the matrix A is equal to each other (Equation (52) below). That is, the sum of the elements of the m-th pattern A m represented by the above Equation (14) may be made equal to each other.

[0126] [Number]

[0127] As a method for setting the matrix A, there is the following first method. Assuming that each element a m,n is either 0 or 1, the number of elements having the value 1 in the m-th pattern A m is made constant. For example, when the number of elements having the value 1 in the m-th pattern A m is 2, the patterns A1 and A2 are set as in the following Equation (53). The m-th pattern A m set in this way satisfies the above Equation (52).

[0128] [Number]

[0129] As a method for setting the matrix A, there is also the following second method. The arbitrarily temporarily set m-th pattern A m is divided by the sum of the elements of that pattern A m , and the result of this division is taken as the m-th pattern A m . For example, assuming that the temporarily set patterns A1 and A2 are as in the following Equation (54), since the sum of the elements of each pattern is 1 and 2, respectively, the patterns A1 and A2 obtained by dividing by the sum of the elements of each pattern are as in the following Equation (55). The m-th pattern A m set in this way satisfies the above Equation (52).

[0130] [Mathematics]

[0131] [Mathematics]

[0132] There is also a third method for setting the matrix A as follows. The arbitrarily temporarily set m-th pattern A m is divided by the inner product α m between the pattern A m and the column vector W (in the following equation (56)), and the division result is used as the m-th pattern A m (in the following equation (57)). The m-th pattern A m set in this way satisfies the above equation (25).

[0133] [Mathematics]

[0134] [Mathematics]

[0135] If the spatial light modulator can realize the multi-tone m-th pattern A m , the second method and the third method are possible. Also, even if the spatial light modulator cannot realize the multi-tone m-th pattern A m , if the intensity of the light output from the light source can be adjusted to multi-tone, the second method and the third method are possible.

[0136] In the first to fourth embodiments described so far, it is necessary to design the system matrix A so as to satisfy predetermined conditions before light irradiation and light intensity value acquisition. However, depending on the light source or the spatial light modulator, the degree of freedom in designing the system matrix A may be low. The fifth to eighth embodiments described below can address such problems.

[0137] Next, the fifth to eighth embodiments will be described. In the fifth to eighth embodiments, as described below, after light irradiation and light intensity value acquisition, the light intensity value and the system matrix are converted to obtain an image of an object excluding W from X. In the first to fourth embodiments, instead of designing the system matrix A so as to satisfy a predetermined condition before light irradiation and light intensity value acquisition, the fifth to eighth embodiments are respectively those in which the light intensity value and the system matrix are converted after light irradiation and light intensity value acquisition.

[0138] That is, in the fifth embodiment, the column vector X is the sum of the first AC component X AC1 , the second AC component X AC2 and the DC component X DC , and the column vector W to be excluded is the sum of the second AC component X AC2 and the DC component X DC .

[0139] In the sixth embodiment, the column vector X is represented as the sum of the AC component X AC and the DC component X DC , and the column vector W to be excluded is only the DC component X DC .

[0140] The seventh embodiment corresponds to an application example of the fifth embodiment. In the seventh embodiment, the column vector X is the sum of the first AC component X AC1 and the first DC component X DC1 , which are the components of the image originally desired to be obtained, and the second AC component X AC2 and the second DC component X DC2 , which are known unnecessary components. The column vector W to be excluded is the sum of the second AC component X AC2 , the first DC component X DC1 and the second DC component X DC2 .

[0141] The eighth embodiment corresponds to an application example of the fifth embodiment. In the eighth embodiment, the column vector X is the first AC component X AC1 , the second AC component X AC2 and the DC component X DC is represented by the sum, and the column vector W to be excluded is the second AC component X AC2 and the DC component X DC is the sum of. In the eighth embodiment, an image (X - W) of an object obtained by excluding W from X is obtained, and then X AC2 is added to the image of the object to improve the image quality of the object.

[0142] Although the fifth to eighth embodiments differ in the determination of the column vector W to be excluded, they are common in obtaining an image of an object obtained by excluding W from X, and will be described together hereinafter.

[0143] The above equation (5) is represented by the following equation (58) when described for each element. Also, when this is divided by α m in the above equation (56), it becomes as follows: equation (59).

[0144]

Equation

[0145]

Equation

[0146] y m / α m is defined as y' m (the following equation (60)). Also, a m,n / α m is defined as a' m,n (the following equation (61)). As a result, equation (59) is represented by the following equation (62).

[0147]

Equation

[0148]

Equation

[0149]

Equation

[0150] y' m Let the column vector with y' as the m-th element be Y', and a' m,n Let the matrix with a' as the element in the m-th row and n-th column be A'. Then, equation (62) becomes the following equation (63). Also, the matrix A' and the column vector W satisfy the following equation (64). Equation (63) corresponds to the above equation (5), and equation (64) corresponds to the above equation (25). Therefore, by using the transformed column vector Y' and matrix A', the image of the object excluding W from X can be obtained.

[0151]

Number

[0152]

Number

[0153] Thus, in the same manner as the prior art, the system matrix A is set to obtain the light intensities y1 to y M After that, the column vector Y is converted to Y', and the system matrix A is converted to A'. Then, using the transformed column vector Y' and matrix A', the image of the object excluding W from X is obtained. However, also in this case, if the AC component X AC of X is represented as the sum of the first AC component X AC1 and the second AC component X AC2 and only the second AC component X AC2 contains W, then the first AC component X AC1 and the second AC component X AC2 need to be orthogonal to each other (the above equation (24)).

[0154] FIG. 5 is a flowchart of obtaining an image of an object by ghost imaging according to the fifth to eighth embodiments.

[0155] In step S21, the control unit 18 sets m, <ay> 、< / ay> < / y> and <y>Perform each initialization. That is, set the pattern number m to 1, <ay> 、< / ay> < / y> and <y>Set each to 0. Also, determine the W to be excluded.

[0156] In step S22, the control unit 18 sets the m-th pattern A m to the spatial light modulator 13, and at that time, obtains the light intensity y m detected by the photodetector 15. At this time, unlike the first to fourth embodiments, in the fifth to eighth embodiments, the system matrix A does not need to satisfy the above equation (25).

[0157] In step S23, the control unit 18 <ay> 、< / ay> < / y> and <y>Perform each update to obtain an image of the object with W excluded from X. That is, first, find α m and then find <ay>to A m y m / α m 2 add them, and use the addition result as the new <ay>shall be. < / ay> < / ay> < / y> Add A m / α m and add the result to a new Let it be so. <y>to y m / α m add them, and use the addition result as the new <y>Let it be so. And these updated <ay> 、< / ay> < / y> < / y> and <y>Using this, an image of the object is calculated. The image at this time corresponds to the sum from m = 1 to m on the right side of the above equation (15). σ A 2 is the variance of the elements of the matrix A' after transformation.

[0158] In step S24, the control unit 18 determines whether to end. For example, when an image of sufficient quality is obtained, or when the predetermined number of patterns M is reached, it ends. If it is determined in step S24 that the process has not yet ended, after the value of m is incremented by 1 in step S25, the process returns to step S22.

[0159] The control unit 18 repeats steps S22 and S23 while incrementing the value of m by 1 in step S25 until it determines to end in step S24. The value of m at the end point becomes the number of patterns M. Also, if necessary, all or part of W obtained by another method may be added to the image of the object excluding W from X.

[0160] Next, the results of the simulation will be described. The ghost imaging technology described in Non-Patent Document 1 was used as a comparative example. The number of pixels N = 128 × 128, and the number of measurement times M = 128 × 128 × 2.

[0161] FIG. 6 is a diagram showing an image of an object or the like used in the simulation. FIG. 6(a) shows the AC component X AC1 and the DC component X DC1 which are components of the image of the object that is originally desired to be obtained. FIG. 6(b) shows the AC component X AC2 and the DC component X DC2 which are components of the unwanted image. The AC component X AC2 varies spatially with a constant period. In this simulation, it is assumed that an unwanted image (FIG. 6(b)) is superimposed on the image of the object that is originally desired to be obtained (FIG. 6(a)). FIG. 7 is a diagram showing the image obtained by the simulation.

[0162] The image in Fig. 7(a) is an image reconstructed by the ghost imaging technology of the seventh embodiment. This image is the DC component X of the object image DC1 and the unnecessary image (X AC2 +X DC2 ) are excluded, and only the AC component X of the object image AC1 is reconstructed.

[0163] The image in Fig. 7(b) is an image reconstructed by the ghost imaging technology of the sixth embodiment. This image is the sum of the DC component X of the object image DC1 and the DC component X of the unnecessary image DC2 is excluded, and the sum of the AC component X of the object image AC1 and the AC component X of the unnecessary image AC2 is reconstructed.

[0164] The image in Fig. 7(c) is an image reconstructed by the ghost imaging technology of the comparative example. This image is the sum of the object image (X AC1 +X DC1 ) and the unnecessary image (X AC2 +X DC2 ) is reconstructed.

[0165] As can be seen by comparing these images, the image obtained by the ghost imaging technology of the seventh embodiment (Fig. 7(a)) is the sum of the DC component X of the object image DC1 and the unnecessary image (X AC2 +X DC2 ) is excluded, and only the AC component X of the object image AC1 is reconstructed, and only the important components of the object image are reconstructed.

[0166] Next, the results of other simulations will be described. The ghost imaging technology described in Non-Patent Document 1 was used as a comparative example. N = 128 × 128 was set. The object image used was the same as that shown in Fig. 6(a), and the image was represented by the sum of the first AC component X AC1 , the second AC component X AC2 and the DC component X DC . Figs. 8 to 10 are diagrams showing the images obtained by the simulation.

[0167] The image in Fig. 8(a) is a low-resolution image (V AC2 ) acquired by a 1-pixel camera. The number of pixels in the image is 32×32, and the number of measurement times was 1024 (=32×32).

[0168] The image in Fig. 8(b) is an image reconstructed by the ghost imaging technology of the second embodiment. This image is the DC component X of the object image DC is excluded, and the sum of the first AC component X AC1 and the second AC component X AC2 of the object image is reconstructed. The number of measurement times was 1638 (=128×128 / 10).

[0169] The image (V AC2 ) in Fig. 8(a) and the image (X AC1 +X AC2 ) in Fig. 8(b) were used to obtain the value of a by the above formula (48), and further aV AC2 was obtained.

[0170] The image in Fig. 9(a) is an image reconstructed by the ghost imaging technology of the fifth embodiment. This image is the sum of aV AC2 and X DC is excluded, and only the first AC component X AC1 of the object image is reconstructed. The number of measurement times was 16384 (=128×128).

[0171] The image in Fig. 9(b) is an image obtained by adding aV AC1 to the image (X AC2 ) in Fig. 9(a). This image corresponds to an image reconstructed by the ghost imaging technology of the eighth embodiment, and the sum of the first AC component X AC1 and the second AC component X AC2 of the object image is reconstructed.

[0172] The image in Fig. 10(a) is an image reconstructed by the ghost imaging technology of the sixth embodiment. This image is the DC component X of the object image DC is excluded, and the first AC component X of the object image AC1 and the second AC component X AC2 which is the sum of them. The number of measurements was 19046 (= 1024 + 1638 + 16384).

[0173] The image in Fig. 10(b) is the image reconstructed by the ghost imaging technology of the comparative example. This image is the image of the object (X AC1 + X AC2 + X DC ) which is reconstructed. The number of measurements was 19046 (= 1024 + 1638 + 16384).

[0174] As can be seen by comparing these images, the image (Fig. 9(b)) obtained by the ghost imaging technology of the eighth embodiment had good image quality.

[0175] Fig. 11 is a graph showing the relationship between the relative error of the value of a obtained from the image (V AC2 ) in Fig. 8(a) and the image (X AC1 + X AC2 ) in Fig. 8(b), and the number of measurements when obtaining the image (X AC1 + X AC2 ) in Fig. 8(b). In this simulation, since the true image (X AC1 + X AC2 ) is known, the value of a obtained from this true image (X AC1 + X AC2 ) and the image (V AC2 ) by the above formula (48) is taken as the true value, and the relative error with respect to this true value of a is obtained. As shown in this graph, for example, even when the number of measurements is 1638 which is about one-tenth of the number of pixels (128 × 128), the relative error is 5% or less. Even if the fluctuation of the value of each pixel of the image (X AC1 + X AC2 ) in Fig. 8(b) is large, when calculating the value of a from the image (V AC2 ) in Fig. 8(a) and the image (X AC1 + X AC2 ) in Fig. 8(b), the positive and negative fluctuations of the values of each pixel cancel each other out, so the relative error of the value of a obtained even with a small number of measurements is small.

[0176] Next, the ninth to twelfth embodiments will be described. In the fifth to eighth embodiments described so far, after light irradiation and light intensity value acquisition, the light intensity value y m is converted by division (the above equation (60)), and the system matrix A is converted (the above equation (61)) to obtain an image of an object excluding W from X. Since the conversion of the light intensity value in the above equation (60) is division, the method of these embodiments is called the "division method". In contrast, in the ninth to twelfth embodiments described below, after light irradiation and light intensity value acquisition, the light intensity value y m is converted by subtraction to obtain an image of an object excluding W from X. The method of these embodiments is called the "subtraction method". The subtraction methods corresponding to the division methods of the fifth to eighth embodiments are the ninth to twelfth embodiments, respectively.

[0177] That is, in the ninth embodiment, the column vector X is the sum of the first AC component X AC1 , the second AC component X AC2 and the DC component X DC , and the column vector W to be excluded is the sum of the second AC component X AC2 and the DC component X DC .

[0178] In the tenth embodiment, the column vector X is represented as the sum of the AC component X AC and the DC component X DC , and the column vector W to be excluded is only the DC component X DC .

[0179] The eleventh embodiment corresponds to an application example of the ninth embodiment. In the eleventh embodiment, the column vector X is the sum of the first AC component X AC1 which is a component of the image originally desired to be obtained, the first DC component X DC1 , and the second AC component X AC2 and the second DC component X DC2 which are known unnecessary components. The column vector W to be excluded is the sum of the second AC component X AC2 , the first DC component X DC1 and the second DC component X DC2 .

[0180] The 12th embodiment corresponds to an application example of the 9th embodiment. In the 12th embodiment, the column vector X is the sum of the first AC component X AC1 , the second AC component X AC2 and the DC component X DC . The column vector W to be excluded is the sum of the second AC component X AC2 and the DC component X DC . In the 12th embodiment, an image (X - W) of an object obtained by excluding W from X is obtained, and then X AC2 is added to the image of the object to improve the image quality of the object.

[0181] Although the 9th to 12th embodiments differ in determining the column vector W to be excluded, they are common in obtaining an image X AC of an object obtained by excluding W from X, and thus will be described together hereinafter.

[0182] The relationship among the system matrix A and the column vectors Y, X, X AC , W is represented by the following equation (65). This equation is converted into the following equation (66). In the 9th to 12th embodiments, after light irradiation and obtaining the light intensity value y m , y m - α m is set as y' m (the following equation (67)). α m is represented by the above equation (56). Since the column vector Y' having y' m as the m-th element is the product of the system matrix A and the column vector X AC , the image X AC of the object obtained by excluding W from X can be obtained by using this Y' and the matrix A.

[0183]

Equation

[0184]

Equation

[0185]

Number

[0186] In this way, similar to the prior art, the system matrix A is set, and after obtaining the light intensities y1 to y M a column vector Y is converted into Y' (Equation (67)), and using the converted column vector Y' and the matrix A, an image of the object excluding W from X is obtained. However, also in this case, the AC component X AC of X is represented as the sum of the first AC component X AC1 and the second AC component X AC2 and when only the second AC component X AC2 of them contains W, it is necessary that the first AC component X AC1 and the second AC component X AC2 are orthogonal to each other (Equation (24) above).

[0187] FIG. 12 is a flowchart of obtaining an image of an object by ghost imaging according to the ninth to twelfth embodiments.

[0188] In step S31, the control unit 18 is m, <ay> 、< / ay> < / y> and <y>Perform each initialization. That is, set the pattern number m to 1, <ay> 、< / ay> < / y> and <y>Set each to 0. Also, determine the W to be excluded.

[0189] In step S32, the control unit 18 sets the m-th pattern A m to the spatial light modulator 13, and at that time, obtains the light intensity y m detected by the photodetector 15. At this time, different from the first to fourth embodiments, in the ninth to twelfth embodiments, the system matrix A does not need to satisfy the above equation (25).

[0190] In step S33, the control unit 18 <ay> 、< / ay> < / y> and <y>Perform each update to obtain an image of the object with W excluded from X. That is, first, find α m and obtain it. <ay>to A m (y m -α m ) is added, and the addition result is a new <ay>shall be. < / ay> < / ay> < / y> Add A m and add the result to the new Let it be so. <y>Add (y m -α m ), and use the addition result as the new <y>Let it be so. And these updated <ay> 、< / ay> < / y> < / y> and <y>Using this, an image of the object is calculated. The image at this time corresponds to the sum from m = 1 to m on the right side of the above equation (15).

[0191] In step S34, the control unit 18 determines whether to end. For example, when an image of sufficient image quality is obtained, or when a predetermined number of patterns M is reached, it ends. If it is determined in step S34 that the process has not ended yet, after the value of m is incremented by 1 in step S35, the process returns to step S32.

[0192] The control unit 18 repeats steps S32 and S33 while incrementing the value of m by 1 in step S35 until it determines to end in step S34. The m at the end point becomes the number of patterns M. Also, if necessary, all or part of W obtained by another method may be added to the image of the object excluding W from X.

[0193] Comparing the division algorithm (the fifth to eighth embodiments) and the subtraction algorithm (the ninth to twelfth embodiments), the following can be said. In the division algorithm, when the excluded W contains only the DC component, w n is constant regardless of n, and α m is the sum of a m,n with respect to n. Therefore, it is preferable in that an image of the object with the DC component completely excluded can be obtained even without prior information about the object. On the other hand, in the division algorithm, when the excluded W contains the AC component in addition to the DC component, α m is the sum of n of the product of the DC component and the AC component w n and a m,n Therefore, prior information about the object is required to obtain an image of the object with the DC component completely excluded. However, when the excluded W contains the DC component and the AC component, by combining the division algorithm and the subtraction algorithm as in the thirteenth embodiment described below, an image of the object with the DC component completely excluded can be obtained even without prior information about the object.

[0194] The column vector X is the first AC component X AC1 The second AC component X AC2 and the DC component X DC The excluded column vector W is represented by the sum of the second AC component X AC2 and the DC component X DC Let's assume that it is the sum of. The first AC component X AC1 and the second AC component X AC2 are orthogonal to each other. In the 13th embodiment, as follows, the DC component X DC is removed by the division algorithm, and the second AC component X AC2 is removed by the subtraction algorithm.

[0195] a m,n Let the sum for n of be β m (Equation (68) below). The n-th element x AC2 of the second AC component X n,AC2 and a m,n Let the value obtained by dividing the sum for n of the product of by β m be γ m (Equation (69) below). y' m = y m / β m - γ m (Equation (70) below). a' m,n = a m,n / β m (Equation (71) below). Let the column vector with y' m as the m-th element be Y', and the matrix with a' m,n as the element in the m-th row and n-th column be A'. By using the transformed column vector Y' and matrix A', the image of the object with W excluded from X can be obtained.

[0196]

Number

[0197]

Number

[0198]

Number

[0199]

Number

[0200] Figure 13 is a flowchart of obtaining an image of an object by ghost imaging according to the 13th embodiment.

[0201] In step S41, the control unit 18 is m, <ay> 、< / ay> < / y> and <y>Perform each initialization. That is, set the pattern number m to 1, and <ay> 、< / ay> < / y> and <y>Set each to 0. Also, determine the W to be excluded.

[0202] In step S42, the control unit 18 sets the m-th pattern A m to the spatial light modulator 13, and acquires the light intensity y m detected by the photodetector 15 at that time. At this time, different from the first to fourth embodiments, in the thirteenth embodiment, the system matrix A does not need to satisfy the above equation (25).

[0203] In step S43, the control unit 18 <ay> 、< / ay> < / y> and <y>Perform each update to obtain an image of the object excluding W from X. That is, first, β m , γ m are obtained. <ay>Add A m (y m / β m -γ m ) / β m and add the addition result to a new <ay>shall be.< / ay> < / ay> < / y> Add A m / β m and add the addition result to a new Let it be so. <y>Add (y m / β m -γ m ), and use the addition result as the new <y>Let it be so. And these updated <ay> 、< / ay> < / y> < / y> and <y>Using this, an image of the object is calculated. The image at this time corresponds to the sum from m = 1 to m on the right side of the above equation (15). σ A 2 is the variance of the elements of the matrix A' after transformation.

[0204] In step S44, the control unit 18 determines whether to end. For example, when an image with sufficient image quality is obtained, or when the predetermined number of patterns M is reached, it ends. If it is determined in step S44 that the process has not ended yet, after the value of m is incremented by 1 in step S45, the process returns to step S42.

[0205] The control unit 18 repeats steps S42 and S43 while incrementing the value of m by 1 in step S45 until it determines to end in step S44. The m at the end point becomes the number of patterns M. Also, if necessary, all or part of W obtained by another method may be added to the image of the object excluding W from X.

[0206] Next, the results of the simulation will be described. Fig. 14(a) shows the low-resolution second AC component X AC2 obtained by a 1-pixel camera (number of pixels 16×16). Fig. 14(b) shows the image (number of pixels 64×64) reconstructed by the ghost imaging technology of the 13th embodiment. The number of measurement times was 4096. Fig. 14(c) shows the image reconstructed by the ghost imaging technology described in Non-Patent Document 1. By the ghost imaging technology of the 13th embodiment, the DC component X DC of the image of the object is removed by the subtraction method, and the second AC component X AC2 of the image of the object is removed by the subtraction method, and only the first AC component X AC1 of the image of the object is reconstructed.

[0207] As described above, according to the present embodiment, since an image of the object excluding W from X is obtained by ghost imaging, the error represented by the above equation (1) is reduced, and a higher-precision image can be reconstructed.

Explanation of Reference Numerals

[0208] 1 to 3... Image acquisition device, 11... Light source, 12... Optical system, 13... Spatial light modulator, 14... Optical system, 15... Photodetector, 16... Beam splitter, 17... Imaging unit, 18... Control unit, 20... Object.< / y> < / ay>

Claims

1. A light source that outputs light, A photodetector that detects the intensity of the light output from the light source and passing through the object, A spatial light modulator provided on the optical path between the light source and the photodetector that spatially modulates the intensity of the light, A control unit that sequentially sets the patterns of the spatial intensity modulation of the light by the spatial light modulator to M different patterns respectively, acquires the light intensity detected by the photodetector during the period set for each of the M patterns, and obtains an image of the object by ghost imaging based on these light intensities and the M patterns, Comprising, The control unit, Of the N regions of the image of the object, the value of the n-th region (n = 1 to N) is the n-th element x ｎ The AC components of the column vector X, which is set as such, are represented as the sum of a first AC component and a second AC component that are orthogonal to each other. When the AC components of the column vector W, which are some of the components included in this column vector X, include only the second AC component among the first AC component and the second AC component, In the m-th pattern (m = 1 to M) among the M patterns, a value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the image of the object is the element a in the m-th row and n-th column ｍ,ｎ A system matrix A, and based on the system matrix A in which all elements of the column vector of the product of A and W are equal to each other, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set for each of the M patterns, and the light intensity y detected by the photodetector when the m-th pattern is set ｍ is obtained, y １ to y Ｍ and a １,１ to a Ｍ,Ｎ Based on this, an image of the object from which the column vector W is excluded from the column vector X is obtained. An image acquisition device.

2. A light source that outputs light, A photodetector that detects the intensity of the light output from the light source and passing through the object, A spatial light modulator provided on the optical path between the light source and the photodetector that spatially modulates the intensity of the light, A control unit that sequentially sets the patterns of the spatial intensity modulation of the light by the spatial light modulator to M different patterns respectively, acquires the light intensity detected by the photodetector during the period set for each of the M patterns, and obtains an image of the object by ghost imaging based on these light intensities and the M patterns, Comprising, The control unit, Let the value of the n-th region (n = 1 to N) among the N regions of the image of the object be the n-th element x ｎ When the column vector X, which has the n-th element x as described above, contains both AC components and DC components, and a column vector W, which is a part of the components included in this column vector X, contains only DC components In the m-th pattern (m = 1 to M) among the M patterns, a value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the image of the object is the element a in the m-th row and n-th column ｍ,ｎ A system matrix A is set, and the sum of the elements in each row is equal to each other. Based on the system matrix A, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set to each of the M patterns. When the m-th pattern is set, the light intensity y ｍ is obtained, y １ to y Ｍ and a １,１ to a Ｍ,Ｎ Based on this, an image of the object from which the column vector W has been excluded from the column vector X is obtained. An image acquisition device.

3. A light source that outputs light, A photodetector that detects the intensity of the light output from the light source and passing through the object, A spatial light modulator provided on the optical path between the light source and the photodetector that spatially modulates the intensity of the light, A control unit that sequentially sets the patterns of the spatial intensity modulation of the light by the spatial light modulator to M different patterns respectively, acquires the light intensity detected by the photodetector during the period set for each of the M patterns, and obtains an image of the object by ghost imaging based on these light intensities and the M patterns, Comprising, The control unit, The value of the n-th region (n = 1 to N) among the N regions of the image of the object is the n-th element x ｎ The AC component of the column vector X, which is the sum of the first AC component and the second AC component whose AC components of the n-th region (n = 1 to N) of the image of the object are orthogonal to each other, and when the AC component of the column vector W, which is a part of the components included in this column vector X, includes only the second AC component among the first AC component and the second AC component In the m-th pattern (m = 1 to M) of the M patterns, a value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the image of the object is the element a in the m-th row and n-th column ｍ,ｎ Based on the system matrix A defined as such, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set for each of the M patterns, and the light intensity y ｍ detected by the photodetector when the m-th pattern is set is obtained The n-th element w of W ｎ and a ｍ,ｎ Let α be the sum over n of the product of them, ｍ and let y' ｍ = y ｍ / α ｍ and let a' ｍ,ｎ = a ｍ,ｎ / α ｍ then,[[]] y' １ to y' Ｍ and a' １,１ to a' Ｍ,Ｎ Based on this, an image of the object from which the column vector W has been excluded from the column vector X is obtained. An image acquisition device.

4. A light source that outputs light, A photodetector that detects the intensity of the light output from the light source and passing through the object, A spatial light modulator provided on the optical path between the light source and the photodetector that spatially modulates the intensity of the light, The control unit sequentially sets the patterns of spatial intensity modulation of light by the spatial light modulator to M different patterns respectively, obtains the light intensity detected by the photodetector during the period set for each of the M patterns, and determines the image of the object by ghost imaging based on these light intensities and the M patterns. comprising The control unit Let the value of the n-th region (n = 1 to N) among the N regions of the image of the object be the n-th element x ｎ When the column vector X, which has the n-th element x as described above, contains both AC components and DC components, and a column vector W, which is a part of the components included in this column vector X, contains only DC components In the m-th pattern (m = 1 to M) among the M patterns, a value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the image of the object is the element a in the m-th row and n-th column ｍ,ｎ Based on the system matrix A defined as such, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set for each of the M patterns, and the light intensity y ｍ detected by the photodetector when the m-th pattern is set is obtained. The n-th element w of W ｎ and a ｍ,ｎ Let α be the sum with respect to n of the product of them, ｍ and let y' ｍ = y ｍ / α ｍ and let a' ｍ,ｎ = a ｍ,ｎ / α ｍ then,[[]] y' １ to y' Ｍ and a' １,１ to a' Ｍ,Ｎ Based on this, an image of the object from which the column vector W has been excluded from the column vector X is obtained. An image acquisition device.

5. A light source that outputs light, A photodetector that detects the intensity of the light output from the light source and passing through the object, A spatial light modulator provided on the optical path between the light source and the photodetector for spatially modulating the intensity of the light, The control unit sequentially sets the patterns of spatial intensity modulation of light by the spatial light modulator to M different patterns respectively, obtains the light intensity detected by the photodetector during the period set for each of the M patterns, and determines the image of the object by ghost imaging based on these light intensities and the M patterns. comprising The control unit Among the N regions of the image of the object, the value of the n-th region (n = 1 to N) is the n-th element x ｎ The AC components of the column vector X, which is the sum of the first AC component and the second AC component whose AC components of the n-th region (n = 1 to N) of the image of the object are orthogonal to each other, and when the AC component of the column vector W, which is a part of the components included in this column vector X, includes only the second AC component among the first AC component and the second AC component, In the m-th pattern (m = 1 to M) among the M patterns, a value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the image of the object is the element a in the m-th row and n-th column ｍ,ｎ Based on the system matrix A defined as such, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set for each of the M patterns, and the light intensity y ｍ detected by the photodetector when the m-th pattern is set is obtained. The n-th element w of W ｎ and a ｍ,ｎ The sum for n of the product of them is α ｍ Let y' ｍ = y ｍ - α ｍ and define it as y' １ to y' Ｍ and a １,１ to a Ｍ,Ｎ Based on this, an image of the object from which the column vector W has been excluded from the column vector X is obtained. An image acquisition device.

6. A light source that outputs light, A photodetector that detects the intensity of the light output from the light source and passing through the object, A spatial light modulator provided on the optical path between the light source and the photodetector for spatially modulating the intensity of the light, The control unit sequentially sets the patterns of spatial intensity modulation of light by the spatial light modulator to M different patterns respectively, obtains the light intensity detected by the photodetector during the period set for each of the M patterns, and determines the image of the object by ghost imaging based on these light intensities and the M patterns. comprising The control unit Of the N regions of the image of the object, the value of the n-th region (n = 1 to N) is the n-th element x ｎ Let the column vector X, where the n-th element is the value of the n-th region (n = 1 to N) of the image of the object, contain AC components and DC components. When the column vector W, which is a part of the components included in this column vector X, contains only DC components, In the m-th pattern (m = 1 to M) among the M patterns, a value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the image of the object is the element a in the m-th row and n-th column ｍ,ｎ Based on the system matrix A defined as such, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set for each of the M patterns, and the light intensity y ｍ detected by the photodetector when the m-th pattern is set is obtained. The n-th element w of W ｎ and a ｍ,ｎ Let α be the sum with respect to n of the product of them ｍ and let y' ｍ = y ｍ - α ｍ and then y' １ to y' Ｍ and a １,１ to a Ｍ,Ｎ Based on this, an image of the object from which the column vector W has been excluded from the column vector X is obtained. An image acquisition device.

7. A light source that outputs light, A photodetector that detects the intensity of the light output from the light source and passing through the object, A spatial light modulator provided on the optical path between the light source and the photodetector for spatially modulating the intensity of the light, The control unit sequentially sets the patterns of spatial intensity modulation of light by the spatial light modulator to M different patterns respectively, obtains the light intensity detected by the photodetector during the period set for each of the M patterns, and determines the image of the object by ghost imaging based on these light intensities and the M patterns. comprising The control unit Among the N regions of the image of the object, the value of the n-th region (n = 1 to N) is the n-th element x ｎ The AC components of the column vector X, which is set as such, are represented as the sum of the first AC component and the second AC component that are orthogonal to each other. When the AC component of the column vector W, which is a part of the components included in this column vector X, includes only the second AC component among the first AC component and the second AC component, In the m-th pattern (m = 1 to M) among the M patterns, a value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the image of the object is the element a in the m-th row and n-th column ｍ,ｎ Based on the system matrix A defined as such, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set for each of the M patterns, and the light intensity y ｍ detected by the photodetector when the m-th pattern is set is obtained. a ｍ,ｎ The sum with respect to n of ｍ is denoted as β, and the sum with respect to n of the product of the n-th element x n,AC2 of the second AC component and a ｍ,ｎ is divided by β ｍ to obtain a value denoted as γ ｍ Let y' ｍ = y ｍ / β ｍ - γ ｍ and let a' ｍ,ｎ = a ｍ,ｎ / β ｍ to obtain y' １ to y' Ｍ and a' １,１ to a' Ｍ,Ｎ Based on this, an image of the object with the column vector W excluded from the column vector X is obtained. An image acquisition device.

8. The control unit adds all or part of the column vector W to the image of the object obtained by excluding the column vector W from the column vector X. The image acquisition device according to any one of claims 1 to 7.

9. The control unit sets the value corresponding to the product of the intensity modulation amount in the region corresponding to the n-th region of the image of the object in the m-th pattern and the light intensity in the n-th region of the object when the light output from the light source reaches the object without passing through the spatial light modulator, as the element a in the m-th row and n-th column of the system matrix A ｍ,ｎ to be The image acquisition device according to any one of claims 1 to 7.

10. A method for obtaining an image of an object by ghost imaging, using a light source that outputs light, a photodetector that detects the intensity of the light output from the light source and passing through the object, and a spatial light modulator that is provided on the optical path between the light source and the photodetector and spatially modulates the intensity of the light. The method sequentially sets the patterns of the spatial intensity modulation of the light by the spatial light modulator to M different patterns, respectively, acquires the light intensity detected by the photodetector during the period set for each of the M patterns, and determines the image of the object based on these light intensities and the M patterns. Of the N regions of the image of the object, the value of the n-th region (n = 1 to N) is the n-th element x ｎ The AC components of the column vector X, which is set as such, are represented as the sum of a first AC component and a second AC component that are orthogonal to each other. When the AC component of the column vector W, which is a part of the components included in this column vector X, includes only the second AC component among the first AC component and the second AC component, In the m-th pattern (m = 1 to M) among the M patterns, a value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the image of the object is the element a in the m-th row and n-th column ｍ,ｎ A system matrix A, based on the system matrix A in which all elements of the column vector of the product of A and W are equal to each other, sequentially sets the spatial intensity modulation pattern of light by the spatial light modulator for each of the M patterns, and the light intensity y detected by the photodetector when the m-th pattern is set ｍ is obtained, y １ ~y Ｍ and a １,１ ~a Ｍ,Ｎ Based on this, an image of the object from which the column vector W has been excluded from the column vector X is obtained. Image acquisition method.

11. A method for obtaining an image of an object by ghost imaging, using a light source that outputs light, a photodetector that detects the intensity of the light output from the light source and passing through the object, and a spatial light modulator that is provided on the optical path between the light source and the photodetector and spatially modulates the intensity of the light. The method sequentially sets the patterns of the spatial intensity modulation of the light by the spatial light modulator to M different patterns, respectively, acquires the light intensity detected by the photodetector during the period set for each of the M patterns, and determines the image of the object based on these light intensities and the M patterns. Let the value of the n-th region (n = 1 to N) among the N regions of the image of the object be the n-th element x ｎ When the column vector X, which has the n-th element x as described above, contains both AC components and DC components, and a column vector W, which is a part of the components included in this column vector X, contains only DC components In the m-th pattern (m = 1 to M) among the M patterns, a value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the image of the object is the element a in the m-th row and n-th column ｍ,ｎ A system matrix A that is set as, based on the system matrix A in which the sum of the elements in each row is equal to each other, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set for each of the M patterns, and the light intensity y detected by the photodetector when the m-th pattern is set ｍ is obtained y １ ~y Ｍ and a １,１ ~a Ｍ,Ｎ Based on y and a, an image of the object from which the column vector W is excluded from the column vector X is obtained. Image acquisition method.

12. A method for obtaining an image of an object by ghost imaging, using a light source that outputs light, a photodetector that detects the intensity of the light output from the light source and passing through the object, and a spatial light modulator that is provided on the optical path between the light source and the photodetector and spatially modulates the intensity of the light. The method sequentially sets the patterns of the spatial intensity modulation of the light by the spatial light modulator to M different patterns, respectively, acquires the light intensity detected by the photodetector during the period set for each of the M patterns, and determines the image of the object based on these light intensities and the M patterns. Of the N regions of the image of the object, the value of the n-th region (n = 1 to N) is the n-th element x ｎ The AC components of the column vector X, which is set as such, are represented as the sum of a first AC component and a second AC component that are orthogonal to each other. When the AC components of the column vector W, which are some of the components included in this column vector X, include only the second AC component among the first AC component and the second AC component, In the m-th pattern (m = 1 to M) among the M patterns, a value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the image of the object is the element a in the m-th row and n-th column ｍ,ｎ Based on the system matrix A defined as such, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set for each of the M patterns, and the light intensity y ｍ detected by the photodetector when the m-th pattern is set is obtained. The n-th element w of W ｎ and a ｍ,ｎ The sum over n of the product of them is α ｍ Let y' ｍ = y ｍ / α ｍ Let a' ｍ,ｎ = a ｍ,ｎ / α ｍ Then y' １ ~y' Ｍ and a' １,１ ~a' Ｍ,Ｎ Based on this, an image of the object from which the column vector W has been excluded from the column vector X is obtained. Image acquisition method.

13. A method for obtaining an image of an object by ghost imaging, using a light source that outputs light, a photodetector that detects the intensity of the light output from the light source and passing through the object, and a spatial light modulator that is provided on the optical path between the light source and the photodetector and spatially modulates the intensity of the light. The method sequentially sets the patterns of the spatial intensity modulation of the light by the spatial light modulator to M different patterns respectively, obtains the light intensities detected by the photodetector during the periods set for each of the M patterns, and determines the image of the object by ghost imaging based on these light intensities and the M patterns. Of the N regions of the image of the object, the value of the n-th region (n = 1 to N) is the n-th element x ｎ When the column vector X, which has as its elements the values of the N regions of the image of the object, contains both an AC component and a DC component, and the column vector W, which is a part of the components included in the column vector X, contains only the DC component In the m-th pattern (m = 1 to M) among the M patterns, a value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the image of the object is the element a in the m-th row and n-th column ｍ,ｎ Based on the system matrix A defined as such, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set for each of the M patterns, and the light intensity y ｍ detected by the photodetector when the m-th pattern is set is obtained The n-th element w of W ｎ and a ｍ,ｎ Let α be the sum with respect to n of the product of them, ｍ and let y' ｍ = y ｍ / α ｍ and let a' ｍ,ｎ = a ｍ,ｎ / α ｍ Then,[[]] y' １ to y' Ｍ and a' １,１ to a' Ｍ,Ｎ Based on this, an image of the object from which the column vector W has been excluded from the column vector X is obtained. Image acquisition method.

14. A method for obtaining an image of an object by ghost imaging, using a light source that outputs light, a photodetector that detects the intensity of the light output from the light source and passing through the object, and a spatial light modulator that is provided on the optical path between the light source and the photodetector and spatially modulates the intensity of the light. The method sequentially sets the patterns of the spatial intensity modulation of the light by the spatial light modulator to M different patterns respectively, obtains the light intensities detected by the photodetector during the periods set for each of the M patterns, and determines the image of the object by ghost imaging based on these light intensities and the M patterns. The value of the n-th region (n = 1 to N) among the N regions of the image of the object is the n-th element x ｎ The AC components of the column vector X, which is the n-th element x, are represented as the sum of the first AC component and the second AC component that are orthogonal to each other. When the AC component of the column vector W, which is a part of the components included in this column vector X, includes only the second AC component among the first AC component and the second AC component, In the m-th pattern (m = 1 to M) among the M patterns, a value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the image of the object is the element a in the m-th row and n-th column ｍ,ｎ Based on the system matrix A defined as such, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set for each of the M patterns, and the light intensity y ｍ detected by the photodetector when the m-th pattern is set is obtained. The n-th element w of W ｎ and a ｍ,ｎ The sum of the products of n is defined as α ｍ Let y' ｍ = y ｍ - α ｍ be defined as y' １ to y' Ｍ and a １,１ to a Ｍ,Ｎ Based on this, an image of the object from which the column vector W is excluded from the column vector X is obtained. Image acquisition method.

15. A method for obtaining an image of an object by ghost imaging, using a light source that outputs light, a photodetector that detects the intensity of the light output from the light source and passing through the object, and a spatial light modulator that is provided on the optical path between the light source and the photodetector and spatially modulates the intensity of the light. The method sequentially sets the patterns of the spatial intensity modulation of the light by the spatial light modulator to M different patterns respectively, obtains the light intensities detected by the photodetector during the periods set for each of the M patterns, and determines the image of the object by ghost imaging based on these light intensities and the M patterns. Let the value of the n-th region (n = 1 to N) among the N regions of the image of the object be the n-th element x ｎ When the column vector X, which has the n-th element x as the value of the n-th region (n = 1 to N) of the image of the object, includes an AC component and a DC component, and the column vector W, which is a part of the components included in this column vector X, includes only the DC component In the m-th pattern (m = 1 to M) among the M patterns, a value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the image of the object is the element a in the m-th row and n-th column ｍ,ｎ Based on the system matrix A defined as such, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set for each of the M patterns, and the light intensity y ｍ detected by the photodetector when the m-th pattern is set is obtained The n-th element w of W ｎ and a ｍ,ｎ The sum over n of the product thereof is α ｍ Let y' ｍ = y ｍ - α ｍ and let y' １ ~y' Ｍ and a １,１ ~a Ｍ,Ｎ Based on this, an image of the object with the column vector W excluded from the column vector X is obtained. Image acquisition method.

16. A method for obtaining an image of an object by ghost imaging, using a light source that outputs light, a photodetector that detects the intensity of the light output from the light source and passing through the object, and a spatial light modulator that is provided on the optical path between the light source and the photodetector and spatially modulates the intensity of the light. The method sequentially sets the patterns of the spatial intensity modulation of the light by the spatial light modulator to M different patterns respectively, obtains the light intensities detected by the photodetector during the periods set for each of the M patterns, and determines the image of the object by ghost imaging based on these light intensities and the M patterns. Among the N regions of the image of the object, the value of the n-th region (n = 1 to N) is the n-th element x ｎ The AC components of the column vector X, which is set as such, are represented as the sum of a first AC component and a second AC component that are orthogonal to each other. When the AC components of the column vector W, which are some of the components included in this column vector X, include only the second AC component among the first AC component and the second AC component, In the m-th pattern (m = 1 to M) among the M patterns, a value corresponding to the intensity modulation amount in the region corresponding to the n-th region of the image of the object is the element a in the m-th row and n-th column ｍ,ｎ Based on the system matrix A defined as such, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set for each of the M patterns, and the light intensity y ｍ detected by the photodetector when the m-th pattern is set is obtained. a ｍ,ｎ Let the sum of β with respect to n of ｍ and let the sum of the product of the n-th element x of the second AC component n,AC2 and a ｍ,ｎ with respect to n be divided by β ｍ to obtain a value γ ｍ Let y' ｍ = y ｍ / β ｍ -γ ｍ Let a' ｍ,ｎ = a ｍ,ｎ / β ｍ and then y' １ ~y' Ｍ and a' １,１ ~a' Ｍ,Ｎ Based on this, an image of the object with the column vector W excluded from the column vector X is obtained. Image acquisition method.

17. Adding all or part of the column vector W to the image of the object obtained by excluding the column vector W from the column vector X. The image acquisition method according to any one of claims 10 to 16.

18. The value corresponding to the product of the intensity modulation amount in the region corresponding to the n-th region of the image of the object in the m-th pattern and the light intensity in the n-th region of the object when the light output from the light source reaches the object without passing through the spatial light modulator is set as the element a at the m-th row and n-th column of the system matrix A ｍ,ｎ to be The image acquisition method according to any one of claims 10 to 16.

Images