Image acquisition device and image acquisition method

Abstract

An image acquisition device 1 comprises a light source 11, a spatial light modulator 13, a photodetector 15, and a control unit 18. The control unit 18 sequentially sets spatial intensity modulation patterns of light produced by the spatial light modulator 13 to M mutually different patterns, acquires the light intensity detected by the photodetector 15 in a period set for each of the M patterns, and obtains an image of an object by ghost imaging on the basis of the light intensities and the M patterns. The control unit 18 performs the ghost imaging by excluding W, which is a component of a portion included in an image X of the object, from X, and obtains an image (X – W) of the object excluding W from X. Thus, there are realized an image acquisition device and an image acquisition method with which it is possible to acquire an image of an object with reduced error by ghost imaging.

Description

Image acquisition device and image acquisition method

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

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

[0003] The photodetector used in ghost imaging technology may be a single-pixel photodetector (point sensor). Therefore, even if it is difficult to obtain a two-dimensional image using an area sensor with multiple pixels arranged two-dimensionally in a wavelength range, if a point sensor with light sensitivity in that wavelength range exists, it is possible to obtain a two-dimensional image of the object by ghost imaging using the point sensor.

[0004] Andrew M. Kingston et al., "Optimizing nonconfigurable, transversely displaced masks for illumination patterns in classical ghost imaging", Physical Review A 107, 2, 023524 (2023)David Ceddia and David M. Paganin, "Random-matrix bases, ghost imaging, and x-ray phase contrast computational ghost imaging", Physical Review A 97, 6, 062119 (2018)

[0005] Since ghost imaging technology uses orthogonal matrix approximation when calculating the correlation between each pattern and each light intensity, it is not possible to completely reconstruct the image of the object with a finite number of patterns M, even under ideal conditions where there is no shot noise.

[0006] Non-Patent Document 2 describes that when a column vector X has elements each representing a pixel value of an image of an object, the error (variance) due to orthogonal matrix approximation can be approximately expressed by the following equation (1): In other words, the image X of an object acquired by ghost imaging contains an error proportional to the sum of the squares of the pixel values ​​of the image X.

[0007] SUMMARY OF THE INVENTION An object of the present invention is to provide an apparatus and method that can acquire an image of an object with reduced error by ghost imaging.

[0008] An embodiment of the first aspect of the present invention is an image acquisition device comprising: (1) a light source that outputs light; (2) a photodetector that detects the intensity of the light output from the light source and transmitted through an object; (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light; and (4) a control unit that sequentially sets M different patterns for the spatial intensity modulation of the light by the spatial light modulator, 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, and (5) the control unit calculates a value of an nth region (n=1 to N) out of N regions of the image of the object as an nth element x ｎ When the AC components of a column vector X are expressed as the sum of a first AC component and a second AC component that are orthogonal to each other, and the AC components of a column vector W, which is a part of the components included in this column vector X, include only the second AC component of the first AC component and the second AC component, a value corresponding to the intensity modulation amount in a region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is expressed as an element a in the mth row and nth column. ｍ,ｎBased 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 to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is ｍ Obtain y １ ~y Ｍ and a １,１ ~a Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0009] An embodiment of the second aspect of the present invention is an image acquisition device comprising: (1) a light source that outputs light; (2) a photodetector that detects the intensity of the light output from the light source and transmitted through an object; (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light; and (4) a control unit that sequentially sets M different patterns for the spatial intensity modulation of the light by the spatial light modulator, 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, and (5) the control unit calculates a value of an nth region (n=1 to N) out of N regions of the image of the object as an nth element x ｎ When a column vector X having the formula: X includes AC components and DC components, and a column vector W, which is a part of the components included in the column vector X, includes only DC components, the value corresponding to the intensity modulation amount in the region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is represented by the element a in the mth row and nth column. ｍ,ｎ The system matrix A is such that the sum of elements in each row is equal to each other, and the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is calculated. ｍ Obtain y １ ~y Ｍ and a １,１ ~a Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0010] An embodiment of the third aspect of the present invention is an image acquisition device comprising: (1) a light source that outputs light; (2) a photodetector that detects the intensity of the light output from the light source and transmitted through an object; (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light; and (4) a control unit that sequentially sets M different patterns for the spatial intensity modulation of the light by the spatial light modulator, 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, and (5) the control unit calculates a value of an nth region (n=1 to N) out of N regions of the image of the object as an nth element x ｎ When the AC components of a column vector X are expressed as the sum of a first AC component and a second AC component that are orthogonal to each other, and the AC components of a column vector W, which is a part of the components included in this column vector X, include only the second AC component of the first AC component and the second AC component, a value corresponding to the intensity modulation amount in a region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is expressed as an element a in the mth row and nth column. ｍ,ｎ Based on the system matrix A, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is ｍ Obtain the n-th element w of W ｎ and a ｍ,ｎ The sum of the products of these with respect to n is α ｍ Let y' ｍ = y ｍ / α ｍ Let a' ｍ,ｎ = a ｍ,ｎ / α ｍ As such, y' １ ~y' Ｍ and a' １,１ ~a' Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0011] An embodiment of the fourth aspect of the present invention is an image acquisition device comprising: (1) a light source that outputs light; (2) a photodetector that detects the intensity of light output from the light source and transmitted through an object; (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light; and (4) a control unit that sequentially sets M different patterns for the spatial intensity modulation of light by the spatial light modulator, 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, and (5) the control unit calculates a value of an nth region (n=1 to N) out of N regions of the image of the object as an nth element x ｎ When a column vector X having the formula: X includes AC components and DC components, and a column vector W, which is a part of the components included in the column vector X, includes only DC components, the value corresponding to the intensity modulation amount in the region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is represented by the element a in the mth row and nth column. ｍ,ｎ Based on the system matrix A, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is ｍ Obtain the n-th element w of W ｎ and a ｍ,ｎ The sum of the products of these with respect to n is α ｍ Let y' ｍ = y ｍ / α ｍ Let a' ｍ,ｎ = a ｍ,ｎ / α ｍ As such, y' １ ~y' Ｍ and a' １,１ ~a' Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0012] An embodiment of the fifth aspect of the present invention is an image acquisition device comprising: (1) a light source that outputs light; (2) a photodetector that detects the intensity of light output from the light source and transmitted through an object; (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light; and (4) a control unit that sequentially sets M different patterns for the spatial intensity modulation of light by the spatial light modulator, 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, and (5) the control unit calculates a value of an nth region (n=1 to N) out of N regions of the image of the object as an nth element x ｎ When the AC components of a column vector X are expressed as the sum of a first AC component and a second AC component that are orthogonal to each other, and the AC components of a column vector W, which is a part of the components included in this column vector X, include only the second AC component of the first AC component and the second AC component, a value corresponding to the intensity modulation amount in a region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is expressed as an element a in the mth row and nth column. ｍ,ｎ Based on the system matrix A, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is ｍ Obtain the n-th element w of W ｎ and a ｍ,ｎ The sum of the products of these with respect to n is α ｍ Let y' ｍ = y ｍ -α ｍ As such, y' １ ~y' Ｍ and a １,１ ~a Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0013] An embodiment of the sixth aspect of the present invention is an image acquisition device comprising: (1) a light source that outputs light; (2) a photodetector that detects the intensity of light output from the light source and transmitted through an object; (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light; and (4) a control unit that sequentially sets M different patterns for the spatial intensity modulation of light by the spatial light modulator, 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, and (5) the control unit calculates a value of an nth region (n=1 to N) out of N regions of the image of the object as an nth element x ｎ When a column vector X having the formula: X includes AC components and DC components, and a column vector W, which is a part of the components included in the column vector X, includes only DC components, the value corresponding to the intensity modulation amount in the region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is represented by the element a in the mth row and nth column. ｍ,ｎ Based on the system matrix A, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is ｍ Obtain the n-th element w of W ｎ and a ｍ,ｎ The sum of the products of these with respect to n is α ｍ Let y' ｍ = y ｍ -α ｍ As such, y' １ ~y' Ｍ and a １,１ ~a Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0014] An embodiment of the seventh aspect of the present invention is an image acquisition device comprising: (1) a light source that outputs light; (2) a photodetector that detects the intensity of light output from the light source and transmitted through an object; (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light; and (4) a control unit that sequentially sets M different patterns for the spatial intensity modulation of light by the spatial light modulator, 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, and (5) the control unit calculates a value of an nth region (n=1 to N) out of N regions of the image of the object as an nth element x ｎ When the AC components of a column vector X are expressed as the sum of a first AC component and a second AC component that are orthogonal to each other, and the AC components of a column vector W, which is a part of the components included in this column vector X, include only the second AC component of the first AC component and the second AC component, a value corresponding to the intensity modulation amount in a region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is expressed as an element a in the mth row and nth column. ｍ,ｎ Based on the system matrix A, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is ｍ Obtain a ｍ,ｎ The sum of n is β ｍ and the n-th element x of the second AC component n,AC2 and a ｍ,ｎ The sum of the products of these with respect to n is β ｍ Divide the value by γ ｍ Let y' ｍ = y ｍ / β ｍ -γ ｍ Let a' ｍ,ｎ = a ｍ,ｎ / β ｍ As such, y' １ ~y' Ｍ and a' １,１ ~a' Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0015] An embodiment of the first aspect of the present invention is an image acquisition method, which uses (1) a light source that outputs light, (2) a photodetector that detects the intensity of the light output from the light source and transmitted through an object, and (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light, (4) sequentially setting M different patterns for the spatial intensity modulation of light by the spatial light modulator, acquiring the light intensity detected by the photodetector during the period set for each of the M patterns, and obtaining an image of the object by ghost imaging based on these light intensities and the M patterns, and (5) calculating the value of an nth region (n=1 to N) out of N regions of the image of the object by an nth element x ｎ When the AC components of a column vector X are expressed as the sum of a first AC component and a second AC component that are orthogonal to each other, and the AC components of a column vector W, which is a part of the components included in this column vector X, include only the second AC component of the first AC component and the second AC component, a value corresponding to the intensity modulation amount in a region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is expressed as an element a in the mth row and nth column. ｍ,ｎ 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 to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is ｍ Obtain y １ ~y Ｍ and a １,１ ~a Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0016] An embodiment of the second aspect of the present invention is an image acquisition method, which uses (1) a light source that outputs light, (2) a photodetector that detects the intensity of the light output from the light source and transmitted through an object, and (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light, (4) sequentially setting M different patterns for the spatial intensity modulation of the light by the spatial light modulator, acquiring the light intensity detected by the photodetector during the period set for each of the M patterns, and obtaining an image of the object by ghost imaging based on these light intensities and the M patterns, and (5) calculating the value of an n-th region (n=1 to N) out of N regions of the image of the object by an n-th element x ｎ When a column vector X having the formula: X includes AC components and DC components, and a column vector W, which is a part of the components included in the column vector X, includes only DC components, the value corresponding to the intensity modulation amount in the region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is represented by the element a in the mth row and nth column. ｍ,ｎ The system matrix A is such that the sum of elements in each row is equal to each other, and the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is calculated. ｍ Obtain y １ ~y Ｍ and a １,１ ~a Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0017] An embodiment of the third aspect of the present invention is an image acquisition method, which uses (1) a light source that outputs light, (2) a photodetector that detects the intensity of the light output from the light source and transmitted through an object, and (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light, (4) sequentially setting M different patterns for the spatial intensity modulation of light by the spatial light modulator, acquiring the light intensity detected by the photodetector during the period set for each of the M patterns, and obtaining an image of the object by ghost imaging based on these light intensities and the M patterns, and (5) calculating the value of an nth region (n=1 to N) out of N regions of the image of the object by an nth element x ｎ When the AC components of a column vector X are expressed as the sum of a first AC component and a second AC component that are orthogonal to each other, and the AC components of a column vector W, which is a part of the components included in this column vector X, include only the second AC component of the first AC component and the second AC component, a value corresponding to the intensity modulation amount in a region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is expressed as an element a in the mth row and nth column. ｍ,ｎ Based on the system matrix A, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is ｍ Obtain the n-th element w of W ｎ and a ｍ,ｎ The sum of the products of these with respect to n is α ｍ Let y' ｍ = y ｍ / α ｍ Let a' ｍ,ｎ = a ｍ,ｎ / α ｍ As such, y' １ ~y' Ｍ and a' １,１ ~a' Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0018] An embodiment of the fourth aspect of the present invention is an image acquisition method, which uses (1) a light source that outputs light, (2) a photodetector that detects the intensity of the light output from the light source and transmitted through an object, and (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light, (4) sequentially setting M different patterns for the spatial intensity modulation of light by the spatial light modulator, acquiring the light intensity detected by the photodetector during the period set for each of the M patterns, and obtaining an image of the object by ghost imaging based on these light intensities and the M patterns, and (5) calculating the value of an nth region (n=1 to N) out of N regions of the image of the object by an nth element x ｎ When a column vector X having the formula: X includes AC components and DC components, and a column vector W, which is a part of the components included in the column vector X, includes only DC components, the value corresponding to the intensity modulation amount in the region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is represented by the element a in the mth row and nth column. ｍ,ｎ Based on the system matrix A, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is ｍ Obtain the n-th element w of W ｎ and a ｍ,ｎ The sum of the products of these with respect to n is α ｍ Let y' ｍ = y ｍ / α ｍ Let a' ｍ,ｎ = a ｍ,ｎ / α ｍ As such, y' １ ~y' Ｍ and a' １,１ ~a' Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0019] An embodiment of the fifth aspect of the present invention is an image acquisition method, which uses (1) a light source that outputs light, (2) a photodetector that detects the intensity of the light output from the light source and transmitted through an object, and (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light, (4) sequentially setting M different patterns for the spatial intensity modulation of light by the spatial light modulator, acquiring the light intensity detected by the photodetector during the period set for each of the M patterns, and obtaining an image of the object by ghost imaging based on these light intensities and the M patterns, and (5) calculating the value of an n-th region (n=1 to N) out of N regions of the image of the object by an n-th element x ｎ When the AC components of a column vector X are expressed as the sum of a first AC component and a second AC component that are orthogonal to each other, and the AC components of a column vector W, which is a part of the components included in this column vector X, include only the second AC component of the first AC component and the second AC component, a value corresponding to the intensity modulation amount in a region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is expressed as an element a in the mth row and nth column. ｍ,ｎ Based on the system matrix A, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is ｍ Obtain the n-th element w of W ｎ and a ｍ,ｎ The sum of the products of these with respect to n is α ｍ Let y' ｍ = y ｍ -α ｍ As such, y' １ ~y' Ｍ and a １,１ ~a Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0020] An embodiment of the sixth aspect of the present invention is an image acquisition method, which uses (1) a light source that outputs light, (2) a photodetector that detects the intensity of the light output from the light source and transmitted through an object, and (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light, (4) sequentially setting M different patterns for the spatial intensity modulation of light by the spatial light modulator, acquiring the light intensity detected by the photodetector during the period set for each of the M patterns, and obtaining an image of the object by ghost imaging based on these light intensities and the M patterns, and (5) calculating the value of an nth region (n=1 to N) out of N regions of the image of the object by an nth element x ｎ When a column vector X having the formula: X includes AC components and DC components, and a column vector W, which is a part of the components included in the column vector X, includes only DC components, the value corresponding to the intensity modulation amount in the region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is represented by the element a in the mth row and nth column. ｍ,ｎ Based on the system matrix A, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is ｍ Obtain the n-th element w of W ｎ and a ｍ,ｎ The sum of the products of these with respect to n is α ｍ Let y' ｍ = y ｍ -α ｍ As such, y' １ ~y' Ｍ and a １,１ ~a Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0021] An embodiment of the seventh aspect of the present invention is an image acquisition method, which uses (1) a light source that outputs light, (2) a photodetector that detects the intensity of the light output from the light source and transmitted through an object, and (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light, (4) sequentially setting M different patterns for the spatial intensity modulation of light by the spatial light modulator, acquiring the light intensity detected by the photodetector during the period set for each of the M patterns, and obtaining an image of the object by ghost imaging based on these light intensities and the M patterns, and (5) calculating the value of an n-th region (n=1 to N) out of N regions of the image of the object by an n-th element x ｎ When the AC components of a column vector X are expressed as the sum of a first AC component and a second AC component that are orthogonal to each other, and the AC components of a column vector W, which is a part of the components included in this column vector X, include only the second AC component of the first AC component and the second AC component, a value corresponding to the intensity modulation amount in a region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is expressed as an element a in the mth row and nth column. ｍ,ｎ Based on the system matrix A, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is ｍ Obtain a ｍ,ｎ The sum of n is β ｍ and the n-th element x of the second AC component n,AC2 and a ｍ,ｎ The sum of the products of these with respect to n is β ｍ Divide the value by γ ｍ Let y' ｍ = y ｍ / β ｍ -γ ｍ Let a' ｍ,ｎ = a ｍ,ｎ / β ｍ As such, y' １ ~y' Ｍ and a' １,１ ~a' Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0022] According to an embodiment of the present invention, an image of an object with reduced errors can be obtained by ghost imaging.

[0023] FIG. 1 is a diagram showing the configuration of image acquisition device 1. FIG. 2 is a diagram showing the configuration of image acquisition device 2. FIG. 3 is a diagram showing the configuration of image acquisition device 3. FIG. 4 is a flowchart for acquiring an image of an object. FIG. 5 is a flowchart for acquiring an image of an object. FIG. 6 is a diagram showing images of the object used in the simulation (a) and (b). FIG. 7 is a diagram showing images obtained by the simulation (a) to (c). FIG. 8 is a diagram showing images obtained by the simulation (a) and (b). FIG. 9 is a diagram showing images obtained by the simulation (a) and (b). FIG. 10 is a diagram showing images obtained by the simulation (a) and (b). FIG. 11 is a diagram showing the image (V) of FIG. 8(a). AC2 ) and the image in FIG. 8(b) (X AC1 +X AC2 ) and the relative error of the value of a obtained from the image (X AC1 +X AC2 12 is a flowchart of the process of acquiring an image of an object. FIG. 13 is a flowchart of the process of acquiring an image of an object. FIG. 14 is a diagram showing images obtained by simulation (a) to (c).

[0024] Hereinafter, embodiments of an image acquisition device and an image acquisition method will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements are designated by the same reference numerals, and duplicate explanations will be omitted. The present invention is not limited to these examples, but is defined by the claims, and all modifications within the meaning and scope equivalent to the claims are intended to be included.

[0025] 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 is configured to obtain an image of an object 20 by ghost imaging. The light source 11 outputs light in a wavelength range to which the photodetector 15 has light sensitivity. The photodetector 15 detects the intensity of light output from the light source 11 and transmitted 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.

[0026] The control unit 18 sequentially sets the spatial intensity modulation pattern of light by the spatial light modulator 13 to M different patterns. The control unit 18 acquires the light intensity detected by the photodetector 15 during the period set for each of the M patterns. The control unit 18 then 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.

[0027] The optical systems 12 and 14 are provided as needed. For example, the optical system 12 expands the beam diameter of light output from the light source 11 and outputs the expanded beam diameter light to the spatial light modulator 13. The optical system 14 collects light that has reached the object 20 and makes the light incident on the light receiving portion of the photodetector 15.

[0028] 2 is a diagram showing the configuration of the image acquisition device 2. Compared to the image acquisition device 1 (FIG. 1), the image acquisition device 2 (FIG. 2) differs in the position of the spatial light modulator 13. 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.

[0029] 3 is a diagram showing the configuration of the image acquisition device 3. Compared to the image acquisition device 1 (FIG. 1), the image acquisition device 3 (FIG. 3) differs in that it further includes a beam splitter 16 and an imaging unit 17. The setting of the pattern of spatial intensity modulation of light by the spatial light modulator 13 does not have to 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 light irradiated onto the object 20 may be changed by moving the diffuser plate in a direction perpendicular to the light propagation direction.

[0030] The beam splitter 16 is provided between the spatial light modulator 13 and the object 20, and splits the light arriving from the spatial light modulator 13 into two beams, outputting one of the beams to the object 20 and outputting the other beam to the imaging unit 17. The imaging unit 17 receives the light arriving 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.

[0031] The image acquisition device for obtaining an image of an object by ghost imaging can have various configurations in addition to the configurations shown in Figures 1 to 3. 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). The image of the object may be acquired based on light that has passed through the object, or based on light that has been reflected by the object.

[0032] In the ghost imaging technique, consider a column vector X, a column vector Y and a system matrix A as follows:

[0033] The column vector X is the nth element x ｎ The column vector X is expressed by the following equation (2): １ ~x Ｎ In this specification, the column vector X may be referred to as an image X. N is an integer of 2 or more, and n is an integer of 1 to N, inclusive.

[0034] The column vector Y is represented by the m-th element y, which represents the light intensity detected by the photodetector 15 when the m-th pattern out of the M patterns is set in the spatial light modulator 13. ｍ The column vector Y is expressed by the following equation (3): １ ~y Ｍ M is an integer of 2 or more, and m is an integer of 1 or more and M or less.

[0035] The system matrix A is a matrix with M rows and N columns that represents the relationship between the column vector X and the column vector Y, and is expressed by the following equation (4): ｍ,ｎ is a value corresponding to the intensity modulation amount in a region corresponding to the nth region of the image of the object in the mth pattern among the M patterns. Also, if the light intensity distribution on 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) can be divided by the light intensity distribution. Alternatively, the element a in the mth row and nth column of the system matrix A can be expressed as ｍ,ｎ may be a value corresponding to the product of the intensity modulation amount in a region of the mth pattern corresponding to the nth region of the image of the object and the light intensity in the nth region of the object.

[0036] The relationship between the column vector X, the column vector Y, and the system matrix A is expressed by the following equation (5). ｎ The value of (the value of the n-th region of the image of the object) is estimated by the following equation (6): In this way, the image X of the object is reconstructed.

[0037] This equation (6) can be derived as follows: Column vector Y is converted into column vector Z using the following equation (7), and matrix A is converted into matrix B using the following equation (8). I is an M-row, M-column identity matrix. J is an M-row, M-column matrix in which all elements have the value 1.

[0038] In this case, 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 of matrix B.

[0039] When the matrix B is approximated by an orthogonal matrix, the following approximate formula (11) is obtained: A 2 is the variance of the elements of matrix A. Using the approximation of equation (11), the above equation (10) becomes the following equation (12). Here, the following equation (13) is used. When this equation (12) is written element by element, it becomes the above equation (6).

[0040] Furthermore, the m-th pattern among the M patterns is expressed by the column vector A ｍ When the above equations (6) and (12) are expressed as follows:

[0041] 4 is a flowchart of acquiring an image of an object by ghost imaging. In this flowchart, <Ay> is a column vector A ｍ and light intensity y ｍ Product A ｍ y ｍ represents the sum of the column vector A ｍ and <y> is the light intensity y ｍ Here, the sum is the sum of each of m=1 to m.

[0042] In step S11, the control unit 18 initializes m, <Ay>, , and <y>. That is, the pattern number m is set to 1, and <Ay>, , and <y> are set to 0.

[0043] In step S12, the control unit 18 ｍ is set in the spatial light modulator 13, and the light intensity y detected by the photodetector 15 at that time is ｍ Get.

[0044] In step S13, the control unit 18 updates <Ay>, , and <y> to obtain the image X of the object. ｍ y ｍ Add the result to <Ay> and set it as the new <Ay>. ｍ Add the result to <y> and set it as the new . ｍ are added together, and the result of this addition is taken as the new <y>. Then, using these updated <Ay>, , and <y>, the image X of the object is calculated. The image X at this time corresponds to the sum of m=1 to m on the right side of the above equation (15).

[0045] In step S14, the control unit 18 determines whether or not to end the process. For example, the process ends when an image X of sufficient image quality is obtained or when a predetermined number of patterns M is reached. If it is determined in step S14 that the process is not yet ending, the value of m is incremented by 1 in step S15, and the process returns to step S12.

[0046] 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. At the end, m becomes the number of patterns M, and the image X at that time is expressed by the above formula (15).

[0047] The image X of the object obtained in this manner contains an error proportional to the sum of squares of each pixel value (the value of each element of column vector X) of image X, as expressed by the above formula (1). In the image acquisition device and image acquisition method of each embodiment described below, in order to reduce this error, ghost imaging is performed by excluding column vector W, which is a component included in column vector X, from column vector X, to obtain an image of the object (X-W) obtained by excluding W from X. The excluded column vector W is either known or can be obtained by another method.

[0048] The excluded column vector W may be an unnecessary component in the image of the object, or may be an important component (or part of it) in the image of the object. In the latter case, all or part of W obtained by another method may be added to the image of the object (X-W) obtained by excluding W. The unnecessary component in the image of the object may be, for example, a noise component or a DC component X DC The important components in the image of the object are, for example, the AC component X AC (or part of it).

[0049] The column vector (image of the object) X is the AC component X AC and DC component X DC The DC component X is expressed as the sum of (Equation (16) below). DC The values ​​of all elements of the AC component X are equal to each other. AC Each element x n,AC The sum of these is 0 (see equation (17) below). When acquiring the image X of the object, the spatially uniform DC component X DC Therefore, the spatially varying AC component X AC is more important.

[0050] DC component DC Each element x n,DC When the value of is c (the following equation (18)), each element x of the column vector X ｎ Since the sum of these is cN (Equation (19) below), the value of c can be determined (Equation (20) below). The bold "1" on the right side of Equation (18) represents a column vector in which all elements have the value 1. In this way, the DC component X of the column vector X is DC and the AC component X of the column vector X can be determined. AC The AC component X can be determined. AC and DC component X DC are orthogonal to each other, and the inner product of the two is 0 (Equation (21) below).

[0051] First, the first embodiment will be described. In the first embodiment, the column vector X has a first AC component XAC1 , second AC component X AC2 and the DC component X DC The excluded column vector W is the sum of the second AC component X included in the column vector X. AC2 and the DC component X DC The first AC component X AC1 and the second AC component X AC2 are orthogonal to each other. That is, the first AC component X AC1 and the second AC component X AC2 The value of the inner product with is 0 (Equation (24) below).

[0052] In this case, the system matrix A is designed so that all elements of the column vector of the product of the matrix A and the column vector W have the same value (see the following equation (25)). The bold "1" on the right side of this equation represents a column vector in which all elements have the value 1.

[0053] 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 to each of M patterns, and calculates the light intensity y detected by the photodetector 15 when the mth pattern is set. ｍ Then, the control unit 18 obtains the image X of the object obtained by excluding W from X using the following equation (26), which is similar to the above equation (12), based on the column vector Y and the system matrix A. AC1 Ask for.

[0054] X obtained from this equation (26) AC1 is perpendicular to W, and W and X AC1 The value of the inner product with is 0 (see equation (27) below). AC1 is X minus W.

[0055] Next, a second embodiment will be described. In the second embodiment, the column vector X is an AC component X AC and the DC component X DCThe column vector W to be excluded is the sum of the DC component X included in the column vector X. DC (Equation (29) below).

[0056] In the second embodiment, the second AC component X AC2 is set to 0. All elements of the column vector W are equal to each other (see equation (30) below). Therefore, the system matrix A can be designed so that the sums of the elements in each row of the matrix A are equal to each other. The system matrix A designed in this way satisfies equation (25) above.

[0057] 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 to each of M patterns, and calculates the light intensity y detected by the photodetector 15 when the mth pattern is set. ｍ Then, the control unit 18 obtains the image X of the object obtained by excluding W from X using the following equation (31), which is similar to the above equation (12), based on the column vector Y and the system matrix A. AC Ask for.

[0058] Next, a 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 a first AC component X, which is a component of an image that is originally desired to be acquired. AC1 and the first DC component X DC1 , and a second AC component X , which is a known unwanted component (e.g., a noise component). AC2 and the second DC component X DC2 , (Equation (32) below). The excluded column vector W is the second AC component X included in the column vector X. AC2 , first DC component X DC1 and the second DC component X DC2 The first AC component X AC1 and the second AC component X AC2 are assumed to be orthogonal to each other, and the first AC component X AC1 and the second AC component XAC2 The value of the inner product with is 0 (the above equation (24)).

[0059] In the third embodiment, the DC component X DC the first DC component X DC1 and the second DC component X DC2 Therefore, in the third embodiment, as in the first embodiment, the image X of the object obtained by excluding W from X is obtained. AC1 can be calculated using the above formula (26).

[0060] In the third embodiment, the first AC component X AC1 and the first DC component X DC1 Since the sum of these is the component of the image that we want to acquire, the first DC component X DC1 It is also necessary to find X DC1 can be calculated, for example, as follows: When light having a spatially uniform intensity distribution is incident on an object, the intensity y of the light passing through the object is calculated. DC is detected by the photodetector 15 (Equation (34) below). DC1 When expressed by the following equation (35), equation (34) becomes the following equation (36). From this, the first DC component X DC1 is obtained (the following equation (37)).

[0061] In this way, the first AC component X, which is the component of the image that is originally desired to be acquired, is obtained. AC1 and the first DC component X DC1 Among these, the first AC component X AC1 is calculated as the image of the object (X-W) obtained by excluding W from X, and the first DC component X DC1 is the light intensity y when light having a spatially uniform intensity distribution is incident on the object. DC is required from.

[0062] Next, a 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, a first AC component X AC1, second AC component X AC2 and the DC component X DC The AC component X is expressed as the sum of (Equation (38) below). AC the first AC component X AC1 and the second AC component X AC2 The way to divide into two is arbitrary, and if one is determined, the other is also determined. AC1 and the second AC component X AC2 and must be orthogonal to each other (the above equation (24)).

[0063] For example, image X' can be obtained by using a low-resolution inverse matrix method or camera measurement at a different wavelength. AC and calculate X as shown in the following formula (39): AC2 to X' AC By ghost imaging, this X AC2 and X DC The sum of these is W, and the image of the object (X-W) is obtained by subtracting W from X. Then, X is added to the image of the object. AC2 In addition, the quality of the image of the object is improved.

[0064] However, this X' AC is X AC1 Therefore, X' is not necessarily orthogonal to AC From unit vector V AC2 (Equation (40) below). 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 this equation (41) are orthogonal to each other. To do this, X (Equation (41)) and V AC2 Since the inner product of is a, a can be set as in the following equation (42).

[0065] The first method for experimentally obtaining the value of a is as follows: A pattern expressed by the following formula (43) is irradiated, and the light intensity y ０The bold "1" on the right side of equation (43) represents a column vector in which all elements have the value 1. In addition, when a pattern represented by a column vector in which all elements have the value 1 is irradiated, the light intensity y １ These light intensities y ０ , y １ Using this, the value of a can be calculated using the following equation (46).

[0066] There is also a second method for experimentally obtaining the value of a: TGI may be obtained and used to find the value of a using the following equation (47).

[0067] There is also a third method for experimentally obtaining the value of a, as follows: an image is obtained from which only the DC component has been removed as in the second embodiment, and this image and V are compared as shown in the following equation (48). AC2 Compared to the second method, the third method is more efficient because it requires fewer measurements. Even if the image quality is poor, the dot product value can be obtained with high accuracy, so there is no need to acquire high-quality images.

[0068] The column vector W to be excluded is expressed by the following equation (49): By excluding W from X and performing ghost imaging, the image X of the object obtained by excluding W from X is obtained. AC1 Then, the image of the object X AC1 , the excluded X AC2 (Equation (50) below) Alternatively, the image X of the object is AC1 The excluded W is added to (Equation (51) below). By doing so, the image X of the object can be reconstructed with high accuracy.

[0069] The flowchart for acquiring an image of an object by ghost imaging in the first to fourth embodiments is the same as that shown 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 that W. Furthermore, if necessary, all or part of W acquired by another method may be added to the image of the object obtained by excluding W from X.

[0070] Next, an example of a method for setting the system matrix A will be described. The first and second methods described below are methods for setting the system matrix A when N=4 in the second embodiment for ease of explanation. In the second embodiment, the system matrix A may be designed so that the sums of the elements in each row of the matrix A are equal to each other (Equation (52) below). That is, the m-th pattern A expressed by the above Equation (14) ｍ The sums of the elements of are equal to each other.

[0071] There is a first method for setting the matrix A as follows. m,n is either 0 or 1, and the m-th pattern A ｍ The number of elements that have a value of 1 in the mth pattern A is fixed. ｍ If the number of elements with value 1 in １ , A ２ is set as shown in the following equation (53). The mth pattern A ｍ satisfies the above equation (52).

[0072] There is also a second method for setting the matrix A as follows: ｍ The pattern A ｍ The result of this division is divided by the sum of the elements of the mth pattern A ｍ For example, the provisionally set pattern A １ , A ２ If the sum of each element of the pattern is 1 or 2, the result of dividing by the sum of each element of the pattern is pattern A. １ , A ２The mth pattern A set in this way is expressed by the following equation (55). ｍ satisfies the above equation (52).

[0073] There is also a third method for setting the matrix A as follows: ｍ The pattern A ｍ and the inner product α of column vector W ｍ (the following equation (56)) and the division result is the m-th pattern A ｍ (Equation (57) below). The mth pattern A set in this way ｍ satisfies the above formula (25).

[0074] The spatial light modulator has a multi-tone mth pattern A ｍ If it is possible to realize the m-th pattern A of multi-tone, the second method and the third method are possible. ｍ Even if it is not possible to realize the above, the second and third methods are possible if the intensity of the light output from the light source can be adjusted to multiple gradations.

[0075] In the first to fourth embodiments described so far, it is necessary to design the system matrix A so as to satisfy certain conditions before irradiating light and acquiring light intensity values. However, depending on the light source or spatial light modulator, there are cases where the degree of freedom in designing the system matrix A is low. The fifth to eighth embodiments described below can address this problem.

[0076] Next, 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 values ​​and system matrix are converted to obtain an image of the object with W excluded from X. Instead of designing the system matrix A to satisfy predetermined conditions before light irradiation and light intensity value acquisition in the first to fourth embodiments, the fifth to eighth embodiments respectively convert the light intensity values ​​and system matrix after light irradiation and light intensity value acquisition.

[0077] That is, in the fifth embodiment, the column vector X is the first AC component X AC1 , second AC component X AC2 and the DC component X DC The excluded column vector W is the second AC component X AC2 and the DC component X DC It is the sum of.

[0078] In the sixth embodiment, the column vector X is an AC component X AC and the DC component X DC The excluded column vector W is expressed as the sum of the DC component X DC Only.

[0079] The seventh embodiment corresponds to an application example of the fifth embodiment. In the seventh embodiment, the column vector X is the first AC component X, which is the component of the image that is originally desired to be acquired. AC1 and the first DC component X DC1 , and the second AC component X, which is a known unwanted component. AC2 and the second DC component X DC2 The excluded column vector W is the second AC component X AC2 , first DC component X DC1 and the second DC component X DC2 It is the sum of.

[0080] The eighth embodiment corresponds to an application example of the fifth embodiment. In the eighth embodiment, the column vector X is a first AC component X AC1 , second AC component X AC2 and the DC component X DC The excluded column vector W is the second AC component X AC2 and the DC component X DC In the eighth embodiment, an image of the object (X-W) is obtained by excluding W from X, and then X is added to the image of the object. AC2 This is added to improve the image quality of the object.

[0081] Although the fifth to eighth embodiments differ in terms of the determination of the column vector W to be excluded, they are common in terms of obtaining an image of the object by excluding W from X, and therefore will be described collectively below.

[0082] The above formula (5) can be expressed as the following formula (58) when written element by element. ｍ When divided by this, the following equation (59) is obtained.

[0083] y ｍ / α ｍ y' ｍ (Equation (60) below). ｍ,ｎ / α ｍ a' ｍ,ｎ (Equation (61) below) As a result, equation (59) can be expressed as equation (62) below.

[0084] y' ｍ Let Y' be a column vector with m-th element, and a' ｍ,ｎ If A' is a matrix having an element in the mth row and nth column, then equation (62) becomes equation (63) below. Furthermore, matrix A' and column vector W satisfy equation (64) below. Equation (63) corresponds to equation (5) above, and equation (64) corresponds to equation (25) above. Therefore, by using the converted column vector Y' and matrix A', it is possible to obtain an image of the object with W excluded from X.

[0085] In this way, the system matrix A is set in the same way as in the prior art, and the light intensity y １ ~y Ｍ After obtaining the above, the column vector Y is converted to Y', and the system matrix A is converted to A', and the converted column vector Y' and matrix A' are used to obtain an image of the object excluding W from X. However, even in this case, the AC component X of X is AC is the first AC component X AC1 and the second AC component X AC2 and the second AC component X AC2 When W contains only the first AC component X AC1 and the second AC component X AC2 and must be orthogonal to each other (the above equation (24)).

[0086] FIG. 5 is a flowchart of the acquisition of an image of an object by ghost imaging according to the fifth to eighth embodiments.

[0087] In step S21, the control unit 18 initializes m, <Ay>, , and <y>. That is, the pattern number m is set to 1, and <Ay>, , and <y> are set to 0. Also, W to be excluded is determined.

[0088] In step S22, the control unit 18 ｍ is set in the spatial light modulator 13, and the light intensity y detected by the photodetector 15 at that time is ｍ 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 formula (25).

[0089] In step S23, the control unit 18 updates each of <Ay>, , and <y> to obtain an image of the object excluding W from X. That is, first, α ｍ <Ay> is A ｍ y ｍ / α ｍ ２ Add the result to <Ay> and set it as the new <Ay>. ｍ / α ｍ Add the result to <y> and set it as the new . ｍ / α ｍ The result of the addition is taken as the new <y>. Then, the image of the object is calculated using these updated <Ay>, , and <y>. The image at this time corresponds to the sum of m=1 to m on the right side of the above equation (15). σ A 2 is the variance of the elements of the transformed matrix A'.

[0090] In step S24, the control unit 18 determines whether or not to end the process. For example, the process ends when an image of sufficient image quality has been obtained or when the predetermined number of patterns M has been reached. If it is determined in step S24 that the process is not yet ending, the value of m is incremented by 1 in step S25, and the process returns to step S22.

[0091] 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 the process in step S24. The value of m at the end of the process becomes the number of patterns M. If necessary, all or part of W obtained by another method may be added to the image of the object obtained by excluding W from X.

[0092] Next, the results of the simulation will be described. The ghost imaging technique described in Non-Patent Document 1 was used as a comparative example. The number of pixels N was set to 128×128, and the number of measurements M was set to 128×128×2.

[0093] 6A and 6B are diagrams showing images of an object used in the simulation. AC1 and the DC component X DC1 6B shows the AC component X AC2 and the DC component X DC2 The AC component X AC2 fluctuates spatially at a constant cycle. In this simulation, we assumed that an unnecessary image (Fig. 6(b)) was superimposed on the image of the object we wanted to acquire (Fig. 6(a)). Fig. 7 shows the image obtained in the simulation.

[0094] The image in Fig. 7(a) is an image reconstructed by the ghost imaging technique of the seventh embodiment. This image is a DC component X DC1 and unwanted image (X AC2 +X DC2 ) is excluded, and the AC component X of the image of the object is AC1 Only the original is reconstructed.

[0095] The image in Fig. 7(b) is an image reconstructed by the ghost imaging technique of the sixth embodiment. This image is a DC component X DC1 and the DC component of the unwanted image X DC2 The sum of the AC components X of the image of the object is excluded. AC1 and the AC component of the unwanted image X AC2 It is a reconstruction of the sum of the two.

[0096] The image in Figure 7(c) is an image reconstructed by the ghost imaging technique of the comparative example. This image is an image of the object (X AC1 +X DC1 ) and unwanted image (X AC2 +X DC2 ) and is a reconstructed sum of them.

[0097] As can be seen from comparing these images, the image obtained by the ghost imaging technique of the seventh embodiment (FIG. 7(a)) has a DC component X DC1 and unwanted image (X AC2 +X DC2 ) is excluded, and the AC component X AC1 Only the important components of the image of the object were reconstructed.

[0098] Next, the results of other simulations will be described. The ghost imaging technique described in Non-Patent Document 1 was used as a comparative example. N=128×128. The image of the object used was the same as that shown in FIG. 6(a), and the first AC component X AC1 , second AC component X AC2 and the DC component X DC 8 to 10 are diagrams showing images obtained by simulation.

[0099] The image in FIG. 8(a) is a low-resolution image (V AC2 The number of pixels in the image was 32 x 32, and the number of measurements was 1024 (= 32 x 32).

[0100] The image in Fig. 8(b) is an image reconstructed by the ghost imaging technique of the second embodiment. This image is a DC component X DC is removed to obtain the first AC component X of the image of the object. AC1 and the second AC component X AC2 The number of measurements was 1638 (= 128 × 128 / 10).

[0101] The image in FIG. AC2 ) and the image in FIG. 8(b) (X AC1 +X AC2 ) to find the value of a using the above equation (48), and then aVAC2 asked for.

[0102] The image in Figure 9(a) is an image reconstructed by the ghost imaging technique of the fifth embodiment. AC2 and X DC The sum of the first AC component X of the image of the object is excluded. AC1 Only the number of measurements was 16,384 (= 128 × 128).

[0103] The image in FIG. 9(b) is the same as the image in FIG. 9(a) (X AC1 ) to aV AC2 This image corresponds to the image reconstructed by the ghost imaging technique of the eighth embodiment, and the first AC component X AC1 and the second AC component X AC2 It is a reconstruction of the sum of the two.

[0104] The image in Fig. 10(a) is an image reconstructed by the ghost imaging technique of the sixth embodiment. This image is a DC component X DC is removed to obtain the first AC component X of the image of the object. AC1 and the second AC component X AC2 The total number of measurements was 19046 (= 1024 + 1638 + 16384).

[0105] The image in Figure 10(b) is an image reconstructed by the ghost imaging technique of the comparative example. This image is an image of the object (X AC1 +X AC2 +X DC The number of measurements was 19046 (=1024 + 1638 + 16384).

[0106] As can be seen from comparing these images, the image obtained by the ghost imaging technique of the eighth embodiment (FIG. 9(b)) had good image quality.

[0107] FIG. 11 shows the image (V AC2 ) and the image in FIG. 8(b) (X AC1 +X AC2 ) and the relative error of the value of a obtained from the image (X AC1 +XAC2 ) and the number of measurements taken to obtain the true image (X AC1 +X AC2 ), we know the true image (X AC1 +X AC2 ) and statue (V AC2 ) and the value of a obtained from the above equation (48) was taken as the true value, and the relative error with respect to this true value of a was calculated.

[0108] As shown in this graph, even if the number of measurements is 1638, which is about one-tenth of the number of pixels (128 x 128), the relative error is 5% or less. AC1 +X AC2 ) even if the fluctuations are large, the image (V AC2 ) and the image in FIG. 8(b) (X AC1 +X AC2 ) the calculation to find the value of a cancels out the positive and negative fluctuations in the values ​​of the pixels, so the relative error in the value of a obtained is small even if the number of measurements is small.

[0109] 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 was transformed by division (the above equation (60)), and the system matrix A was transformed (the above equation (61)) to obtain an image of the object with W excluded from X. Since the transformation of the light intensity value in the above equation (60) is a division, the technique of these embodiments is called the "division method."

[0110] In contrast to this, in the ninth to twelfth embodiments described below, after light irradiation and light intensity value acquisition, the light intensity value y ｍ is transformed by subtraction to obtain an image of the object with W excluded from X. The techniques of these embodiments are called "subtraction methods." The subtraction methods corresponding to the division methods of the fifth to eighth embodiments are called the ninth to twelfth embodiments, respectively.

[0111] That is, in the ninth embodiment, the column vector X is the first AC component X AC1 , second AC component X AC2 and the DC component XDC The excluded column vector W is the second AC component X AC2 and the DC component X DC It is the sum of.

[0112] In the tenth embodiment, the column vector X is an AC component X AC and the DC component X DC The excluded column vector W is expressed as the sum of the DC component X DC Only.

[0113] The eleventh embodiment corresponds to an application example of the ninth embodiment. In the eleventh embodiment, the column vector X is the first AC component X, which is the component of the image that is originally desired to be acquired. AC1 and the first DC component X DC1 , and the second AC component X, which is a known unwanted component. AC2 and the second DC component X DC2 The excluded column vector W is the second AC component X AC2 , first DC component X DC1 and the second DC component X DC2 It is the sum of.

[0114] The twelfth embodiment corresponds to an application example of the ninth embodiment. In the twelfth embodiment, the column vector X is a first AC component X AC1 , second AC component X AC2 and the DC component X DC The excluded column vector W is the second AC component X AC2 and the DC component X DC In the twelfth embodiment, an image of the object (X-W) is obtained by excluding W from X, and then X is added to the image of the object. AC2 This is added to improve the image quality of the object.

[0115] Although the ninth to twelfth embodiments differ in terms of determining the column vector W to be excluded, the image X of the object obtained by excluding W from X is AC Since the acquisition of the above is common, they will be explained together below.

[0116] System matrix A and column vectors Y, X, X AC, W is expressed by the following equation (65): This equation is transformed into the following equation (66): In the ninth to twelfth embodiments, the light irradiation and the light intensity value y ｍ After acquisition, y ｍ -α ｍ y' ｍ (Equation (67) below) ｍ is expressed by the above formula (56). ｍ As can be seen from equation (66), the column vector Y' with the mth element is the system matrix A and the column vector X AC Therefore, by using this Y' and matrix A, the image of the object excluding W from X can be obtained as follows: AC can be obtained.

[0117] In this way, the system matrix A is set in the same way as in the prior art, and the light intensity y １ ~y Ｍ After obtaining the above, the column vector Y is converted to Y' (equation (67)), and the converted column vector Y' and matrix A are used to obtain the image of the object obtained by excluding W from X. However, even in this case, the AC component X of X is AC is the first AC component X AC1 and the second AC component X AC2 and the second AC component X AC2 When W contains only the first AC component X AC1 and the second AC component X AC2 and must be orthogonal to each other (the above equation (24)).

[0118] FIG. 12 is a flowchart of the acquisition of an image of an object by ghost imaging according to the ninth to twelfth embodiments.

[0119] In step S31, the control unit 18 initializes m, <Ay>, , and <y>. That is, the pattern number m is set to 1, and <Ay>, , and <y> are set to 0. In addition, W to be excluded is determined.

[0120] In step S32, the control unit 18 ｍis set in the spatial light modulator 13, and the light intensity y detected by the photodetector 15 at that time is ｍ At this time, unlike the first to fourth embodiments, in the ninth to twelfth embodiments, the system matrix A does not need to satisfy the above formula (25).

[0121] In step S33, the control unit 18 updates each of <Ay>, , and <y> to obtain an image of the object excluding W from X. That is, first, α ｍ <Ay> is A ｍ (y ｍ -α ｍ ) and the result of the addition is the new <Ay>. ｍ Add the result of the addition to and set it to (y ｍ -α ｍ ) and the result of this addition is taken as the new <y>. The image of the object is then calculated using these updated <Ay>, , and <y>. This image corresponds to the sum of m = 1 to m on the right side of equation (15) above.

[0122] In step S34, the control unit 18 determines whether or not to end the process. For example, the process ends when an image of sufficient image quality has been obtained or when the predetermined number of patterns M has been reached. If it is determined in step S34 that the process is not yet ending, the value of m is incremented by 1 in step S35, and the process returns to step S32.

[0123] 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 the process in step S34. The value of m at the end of the process becomes the number of patterns M. Furthermore, if necessary, all or part of W obtained by another method may be added to the image of the object obtained by excluding W from X.

[0124] Comparing the division method (fifth to eighth embodiments) with the subtraction method (ninth to twelfth embodiments), the following can be said. In the division method, when the excluded W contains only a DC component, w ｎ is constant regardless of n, and α ｍ Haa ｍ,ｎThis is preferable in that it is possible to obtain an image of the object from which the DC component has been completely removed, even if there is no prior information about the object.

[0125] On the other hand, in the division method, if the excluded W contains AC components in addition to DC components, α ｍ is the sum of the DC and AC components w n and a ｍ,ｎ Since the sum of the products of W and ω with respect to n is obtained, prior information about the object is required to obtain an image of the object from which the DC component has been completely removed. However, when the W to be removed includes a DC component and an AC component, by combining the division method and the subtraction method as in the thirteenth embodiment described next, it is possible to obtain an image of the object from which the DC component has been completely removed, even without prior information about the object.

[0126] The column vector X is the first AC component X AC1 , second AC component X AC2 and the DC component X DC The excluded column vector W is the second AC component X AC2 and the DC component X DC The first AC component X AC1 and the second AC component X AC2 In the thirteenth embodiment, the DC component X DC is removed by division to obtain the second AC component X AC2 is removed by subtraction.

[0127] a ｍ,ｎ The sum of n is β ｍ (Equation (68) below) The second AC component X AC2 The nth element x of n,AC2 and a ｍ,ｎ The sum of the products of these with respect to n is β ｍ Divide the value by γ ｍ (Equation (69) below). ｍ = y ｍ / β ｍ -γ ｍ (Equation (70) below). ｍ,ｎ = a ｍ,ｎ / β ｍ (Equation (71) below). ｍLet Y' be a column vector with m-th element, and a' ｍ,ｎ The matrix A' is defined as the element of the mth row and nth column. By using the converted column vector Y' and matrix A', it is possible to obtain an image of the object excluding W from X.

[0128] FIG. 13 is a flowchart of the process of acquiring an image of an object by ghost imaging according to the thirteenth embodiment.

[0129] In step S41, the control unit 18 initializes m, <Ay>, , and <y>. That is, the pattern number m is set to 1, and <Ay>, , and <y> are set to 0. In addition, W to be excluded is determined.

[0130] In step S42, the control unit 18 ｍ is set in the spatial light modulator 13, and the light intensity y detected by the photodetector 15 at that time is ｍ At this time, unlike the first to fourth embodiments, in the thirteenth embodiment, the system matrix A does not need to satisfy the above equation (25).

[0131] In step S43, the control unit 18 updates each of <Ay>, , and <y> to obtain an image of the object excluding W from X. That is, first, β ｍ , γ ｍ <Ay> is A ｍ (y ｍ / β ｍ -γ ｍ ) / β ｍ Add the result to <Ay> and set it as the new <Ay>. ｍ / β ｍ Add the result of the addition to and set it to (y ｍ / β ｍ -γ ｍ ) are added together and the result of the addition is taken as the new <y>. Then, the image of the object is calculated using these updated <Ay>, and <y>. The image at this time corresponds to the sum of m = 1 to m on the right side of the above equation (15). σA 2 is the variance of the elements of the transformed matrix A'.

[0132] In step S44, the control unit 18 determines whether or not to end the process. For example, the process ends when an image of sufficient image quality has been obtained or when the predetermined number of patterns M has been reached. If it is determined in step S44 that the process is not yet ending, the value of m is incremented by 1 in step S45, and the process returns to step S42.

[0133] 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 the process in step S44. The value of m at the end of the process becomes the number of patterns M. If necessary, all or part of W obtained by another method may be added to the image of the object obtained by excluding W from X.

[0134] Next, the results of the simulation will be described. Fig. 14(a) shows the second AC component X of low resolution captured by a one-pixel camera. AC2 FIG. 14(b) is an image (64×64 pixels) reconstructed by the ghost imaging technique of the thirteenth embodiment. The number of measurements was 4096. FIG. 14(c) is an image reconstructed by the ghost imaging technique described in Non-Patent Document 1. The ghost imaging technique of the thirteenth embodiment reconstructs the DC component X of the image of the object. DC is removed by division, and the second AC component X AC2 is subtracted to obtain the first AC component X of the image of the object. AC1 Only was reconstructed.

[0135] As described above, according to this embodiment, an image of the object obtained by excluding W from X is acquired by ghost imaging, so the error expressed by the above formula (1) is reduced, and an image with higher accuracy can be reconstructed.

[0136] The image acquisition device and the image acquisition method are not limited to the above-described embodiment and configuration example, and various modifications are possible.

[0137] The image acquisition device of the first aspect according to the above embodiment includes: (1) a light source that outputs light; (2) a photodetector that detects the intensity of the light output from the light source and transmitted through an object; (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light; and (4) a control unit that sequentially sets M different patterns for the spatial intensity modulation of light by the spatial light modulator, 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, and (5) the control unit calculates the value of an nth region (n=1 to N) out of N regions of the image of the object by an nth element x ｎ When the AC components of a column vector X are expressed as the sum of a first AC component and a second AC component that are orthogonal to each other, and the AC components of a column vector W, which is a part of the components included in this column vector X, include only the second AC component of the first AC component and the second AC component, a value corresponding to the intensity modulation amount in a region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is expressed as an element a in the mth row and nth column. ｍ,ｎ 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 to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is ｍ Obtain y １ ~y Ｍ and a １,１ ~a Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0138] The image acquisition device of the second aspect according to the above embodiment includes: (1) a light source that outputs light; (2) a photodetector that detects the intensity of the light output from the light source and transmitted through an object; (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light; and (4) a control unit that sequentially sets M different patterns for the spatial intensity modulation of light by the spatial light modulator, 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, and (5) the control unit calculates the value of an nth region (n=1 to N) out of N regions of the image of the object by an nth element x ｎ When a column vector X having the formula: X includes AC components and DC components, and a column vector W, which is a part of the components included in the column vector X, includes only DC components, the value corresponding to the intensity modulation amount in the region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is represented by the element a in the mth row and nth column. ｍ,ｎ The system matrix A is such that the sum of elements in each row is equal to each other, and the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is calculated. ｍ Obtain y １ ~y Ｍ and a １,１ ~a Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0139] The image acquisition device of the third aspect according to the above embodiment includes: (1) a light source that outputs light; (2) a photodetector that detects the intensity of light output from the light source and transmitted through an object; (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light; and (4) a control unit that sequentially sets M different patterns for the spatial intensity modulation of light by the spatial light modulator, 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, and (5) the control unit calculates the value of an nth region (n=1 to N) among N regions of the image of the object by an nth element x ｎ When the AC components of a column vector X are expressed as the sum of a first AC component and a second AC component that are orthogonal to each other, and the AC components of a column vector W, which is a part of the components included in this column vector X, include only the second AC component of the first AC component and the second AC component, a value corresponding to the intensity modulation amount in a region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is expressed as an element a in the mth row and nth column. ｍ,ｎ Based on the system matrix A, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is ｍ Obtain the n-th element w of W ｎ and a ｍ,ｎ The sum of the products of these with respect to n is α ｍ Let y' ｍ = y ｍ / α ｍ Let a' ｍ,ｎ = a ｍ,ｎ / α ｍ As such, y' １ ~y' Ｍ and a' １,１ ~a' Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0140] The image acquisition device of a fourth aspect according to the above embodiment includes: (1) a light source that outputs light; (2) a photodetector that detects the intensity of light output from the light source and transmitted through an object; (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light; and (4) a control unit that sequentially sets M different patterns for the spatial intensity modulation of light by the spatial light modulator, 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, and (5) the control unit calculates the value of an nth region (n=1 to N) among N regions of the image of the object by an nth element x ｎ When a column vector X having the formula: X includes AC components and DC components, and a column vector W, which is a part of the components included in the column vector X, includes only DC components, the value corresponding to the intensity modulation amount in the region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is represented by the element a in the mth row and nth column. ｍ,ｎ Based on the system matrix A, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is ｍ Obtain the n-th element w of W ｎ and a ｍ,ｎ The sum of the products of these with respect to n is α ｍ Let y' ｍ = y ｍ / α ｍ Let a' ｍ,ｎ = a ｍ,ｎ / α ｍ As such, y' １ ~y' Ｍ and a' １,１ ~a' Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0141] The image acquisition device of a fifth aspect according to the above embodiment includes: (1) a light source that outputs light; (2) a photodetector that detects the intensity of light output from the light source and transmitted through an object; (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light; and (4) a control unit that sequentially sets M different patterns for the spatial intensity modulation of light by the spatial light modulator, 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, and (5) the control unit calculates the value of an nth region (n=1 to N) among N regions of the image of the object by an nth element x ｎ When the AC components of a column vector X are expressed as the sum of a first AC component and a second AC component that are orthogonal to each other, and the AC components of a column vector W, which is a part of the components included in this column vector X, include only the second AC component of the first AC component and the second AC component, a value corresponding to the intensity modulation amount in a region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is expressed as an element a in the mth row and nth column. ｍ,ｎ Based on the system matrix A, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is ｍ Obtain the n-th element w of W ｎ and a ｍ,ｎ The sum of the products of these with respect to n is α ｍ Let y' ｍ = y ｍ -α ｍ As such, y' １ ~y' Ｍ and a １,１ ~a Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0142] The image acquisition device of a sixth aspect according to the above embodiment includes: (1) a light source that outputs light; (2) a photodetector that detects the intensity of light output from the light source and transmitted through an object; (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light; and (4) a control unit that sequentially sets M different patterns for the spatial intensity modulation of light by the spatial light modulator, 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, and (5) the control unit calculates the value of an nth region (n=1 to N) among N regions of the image of the object by an nth element x ｎ When a column vector X having the formula: X includes AC components and DC components, and a column vector W, which is a part of the components included in the column vector X, includes only DC components, the value corresponding to the intensity modulation amount in the region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is represented by the element a in the mth row and nth column. ｍ,ｎ Based on the system matrix A, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is ｍ Obtain the n-th element w of W ｎ and a ｍ,ｎ The sum of the products of these with respect to n is α ｍ Let y' ｍ = y ｍ -α ｍ As such, y' １ ~y' Ｍ and a １,１ ~a Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0143] The image acquisition device of a seventh aspect according to the above embodiment includes: (1) a light source that outputs light; (2) a photodetector that detects the intensity of light output from the light source and transmitted through an object; (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light; and (4) a control unit that sequentially sets M different patterns for the spatial intensity modulation of light by the spatial light modulator, 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, and (5) the control unit calculates the value of an nth region (n=1 to N) among N regions of the image of the object by an nth element x ｎ When the AC components of a column vector X are expressed as the sum of a first AC component and a second AC component that are orthogonal to each other, and the AC components of a column vector W, which is a part of the components included in this column vector X, include only the second AC component of the first AC component and the second AC component, a value corresponding to the intensity modulation amount in a region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is expressed as an element a in the mth row and nth column. ｍ,ｎ Based on the system matrix A, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is ｍ Obtain a ｍ,ｎ The sum of n is β ｍ and the n-th element x of the second AC component n,AC2 and a ｍ,ｎ The sum of the products of these with respect to n is β ｍ Divide the value by γ ｍ Let y' ｍ = y ｍ / β ｍ -γ ｍ Let a' ｍ,ｎ = a ｍ,ｎ / β ｍ As such, y' １ ~y' Ｍ and a' １,１ ~a' Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0144] In the image acquisition device of the eighth aspect, in the configuration of any of the first to seventh aspects, the control unit may be configured to add all or part of the column vector W to an image of the object obtained by excluding the column vector W from the column vector X.

[0145] In the image acquisition device of the ninth aspect, in the configuration of any one of the first to eighth aspects, the control unit calculates a value corresponding to the product of the intensity modulation amount in a region corresponding to the nth region of the image of the object in the mth pattern and the light intensity in the nth region of the object when the light output from the light source reaches the object without passing through the spatial light modulator, as element a in the mth row and nth column of the system matrix A. ｍ,ｎ The configuration may be as follows.

[0146] The image acquisition method of the first aspect according to the above embodiment is a method using (1) a light source that outputs light, (2) a photodetector that detects the intensity of the light output from the light source and transmitted through an object, and (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light, (4) sequentially setting M different patterns for the spatial intensity modulation of light by the spatial light modulator, acquiring the light intensity detected by the photodetector during the period set for each of the M patterns, and obtaining an image of the object by ghost imaging based on these light intensities and the M patterns, and (5) calculating the value of an n-th region (n=1 to N) out of N regions of the image of the object by an n-th element x ｎ When the AC components of a column vector X are expressed as the sum of a first AC component and a second AC component that are orthogonal to each other, and the AC components of a column vector W, which is a part of the components included in this column vector X, include only the second AC component of the first AC component and the second AC component, a value corresponding to the intensity modulation amount in a region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is expressed as an element a in the mth row and nth column. ｍ,ｎ 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 to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is ｍ Obtain y １ ~y Ｍand a １,１ ~a Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0147] The image acquisition method of the second aspect according to the above embodiment is a method using (1) a light source that outputs light, (2) a photodetector that detects the intensity of the light that has been output from the light source and passed through an object, and (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light, (4) sequentially setting M different patterns for the spatial intensity modulation of light by the spatial light modulator, and acquiring the light intensity detected by the photodetector during the period set for each of the M patterns, and obtaining an image of the object by ghost imaging based on these light intensities and the M patterns, and (5) calculating the value of an n-th region (n=1 to N) out of N regions of the image of the object by an n-th element x ｎ When a column vector X having the formula: X includes AC components and DC components, and a column vector W, which is a part of the components included in the column vector X, includes only DC components, the value corresponding to the intensity modulation amount in the region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is represented by the element a in the mth row and nth column. ｍ,ｎ The system matrix A is such that the sum of elements in each row is equal to each other, and the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is calculated. ｍ Obtain y １ ~y Ｍ and a １,１ ~a Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0148] The image acquisition method of the third aspect according to the above embodiment is a method using (1) a light source that outputs light, (2) a photodetector that detects the intensity of the light output from the light source and transmitted through an object, and (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light, (4) sequentially setting M different patterns for the spatial intensity modulation of light by the spatial light modulator, and acquiring the light intensity detected by the photodetector during the period set for each of the M patterns, and obtaining an image of the object by ghost imaging based on these light intensities and the M patterns, and (5) calculating the value of an n-th region (n=1 to N) out of N regions of the image of the object by an n-th element x ｎ When the AC components of a column vector X are expressed as the sum of a first AC component and a second AC component that are orthogonal to each other, and the AC components of a column vector W, which is a part of the components included in this column vector X, include only the second AC component of the first AC component and the second AC component, a value corresponding to the intensity modulation amount in a region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is expressed as an element a in the mth row and nth column. ｍ,ｎ Based on the system matrix A, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is ｍ Obtain the n-th element w of W ｎ and a ｍ,ｎ The sum of the products of these with respect to n is α ｍ Let y' ｍ = y ｍ / α ｍ Let a' ｍ,ｎ = a ｍ,ｎ / α ｍ As such, y' １ ~y' Ｍ and a' １,１ ~a' Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0149] The image acquisition method of the fourth aspect according to the above embodiment is a method using (1) a light source that outputs light, (2) a photodetector that detects the intensity of the light that has been output from the light source and passed through an object, and (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light, (4) sequentially setting M different patterns for the spatial intensity modulation of light by the spatial light modulator, and acquiring the light intensity detected by the photodetector during the period set for each of the M patterns, and obtaining an image of the object by ghost imaging based on these light intensities and the M patterns, and (5) calculating the value of an n-th region (n=1 to N) out of N regions of the image of the object by an n-th element x ｎ When a column vector X having the formula: X includes AC components and DC components, and a column vector W, which is a part of the components included in the column vector X, includes only DC components, the value corresponding to the intensity modulation amount in the region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is represented by the element a in the mth row and nth column. ｍ,ｎ Based on the system matrix A, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is ｍ Obtain the n-th element w of W ｎ and a ｍ,ｎ The sum of the products of these with respect to n is α ｍ Let y' ｍ = y ｍ / α ｍ Let a' ｍ,ｎ = a ｍ,ｎ / α ｍ As such, y' １ ~y' Ｍ and a' １,１ ~a' Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0150] The image acquisition method of the fifth aspect according to the above embodiment is a method using (1) a light source that outputs light, (2) a photodetector that detects the intensity of the light that has been output from the light source and passed through an object, and (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light, (4) sequentially setting M different patterns for the spatial intensity modulation of light by the spatial light modulator, and acquiring the light intensity detected by the photodetector during the period set for each of the M patterns, and obtaining an image of the object by ghost imaging based on these light intensities and the M patterns, and (5) calculating the value of an n-th region (n=1 to N) out of N regions of the image of the object by an n-th element x ｎ When the AC components of a column vector X are expressed as the sum of a first AC component and a second AC component that are orthogonal to each other, and the AC components of a column vector W, which is a part of the components included in this column vector X, include only the second AC component of the first AC component and the second AC component, a value corresponding to the intensity modulation amount in a region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is expressed as an element a in the mth row and nth column. ｍ,ｎ Based on the system matrix A, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is ｍ Obtain the n-th element w of W ｎ and a ｍ,ｎ The sum of the products of these with respect to n is α ｍ Let y' ｍ = y ｍ -α ｍ As such, y' １ ~y' Ｍ and a １,１ ~a Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0151] The image acquisition method of the sixth aspect according to the above embodiment is a method using (1) a light source that outputs light, (2) a photodetector that detects the intensity of the light that has been output from the light source and passed through an object, and (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light, (4) sequentially setting M different patterns for the spatial intensity modulation of light by the spatial light modulator, and acquiring the light intensity detected by the photodetector during the period set for each of the M patterns, and obtaining an image of the object by ghost imaging based on these light intensities and the M patterns, and (5) calculating the value of an n-th region (n=1 to N) out of N regions of the image of the object by an n-th element x ｎ When a column vector X having the formula: X includes AC components and DC components, and a column vector W, which is a part of the components included in the column vector X, includes only DC components, the value corresponding to the intensity modulation amount in the region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is represented by the element a in the mth row and nth column. ｍ,ｎ Based on the system matrix A, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is ｍ Obtain the n-th element w of W ｎ and a ｍ,ｎ The sum of the products of these with respect to n is α ｍ Let y' ｍ = y ｍ -α ｍ As such, y' １ ~y' Ｍ and a １,１ ~a Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0152] The image acquisition method of the seventh aspect according to the above embodiment is a method using (1) a light source that outputs light, (2) a photodetector that detects the intensity of the light that has been output from the light source and passed through an object, and (3) a spatial light modulator that is provided on an optical path between the light source and the photodetector and that spatially intensity-modulates the light, (4) sequentially setting M different patterns for the spatial intensity modulation of light by the spatial light modulator, and acquiring the light intensity detected by the photodetector during the period set for each of the M patterns, and obtaining an image of the object by ghost imaging based on these light intensities and the M patterns, and (5) calculating the value of an n-th region (n=1 to N) out of N regions of the image of the object by an n-th element x ｎ When the AC components of a column vector X are expressed as the sum of a first AC component and a second AC component that are orthogonal to each other, and the AC components of a column vector W, which is a part of the components included in this column vector X, include only the second AC component of the first AC component and the second AC component, a value corresponding to the intensity modulation amount in a region corresponding to the nth region of the image of the object in the mth pattern (m=1 to M) among the M patterns is expressed as an element a in the mth row and nth column. ｍ,ｎ Based on the system matrix A, the spatial intensity modulation pattern of light by the spatial light modulator is sequentially set to each of M patterns, and the light intensity y detected by the photodetector when the mth pattern is set is ｍ Obtain a ｍ,ｎ The sum of n is β ｍ and the n-th element x of the second AC component n,AC2 and a ｍ,ｎ The sum of the products of these with respect to n is β ｍ Divide the value by γ ｍ Let y' ｍ = y ｍ / β ｍ -γ ｍ Let a' ｍ,ｎ = a ｍ,ｎ / β ｍ As such, y' １ ~y' Ｍ and a' １,１ ~a' Ｍ,Ｎ Based on the above, an image of the object is obtained by excluding the column vector W from the column vector X.

[0153] In the image acquisition method of the eighth aspect, in the configuration of any one of the first to seventh aspects, all or part of the column vector W may be added to an image of the object obtained by excluding the column vector W from the column vector X.

[0154] In the image acquisition method of the ninth aspect, in the configuration of any one of the first to eighth aspects, a value corresponding to the product of the intensity modulation amount in a region corresponding to the nth region of the image of the object in the mth pattern and the light intensity in the nth region of the object when the light output from the light source reaches the object without passing through the spatial light modulator is calculated as element a in the mth row and nth column of the system matrix A. ｍ,ｎ The configuration may be as follows.

[0155] The present invention can be used as an image acquisition device and an image acquisition method that can acquire an image of an object with reduced errors by ghost imaging.

[0156] 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.

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 an 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, and 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 intensities detected by the photodetector during the periods 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. 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, the 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 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 values, 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 at the time of setting the m-th pattern is acquired. Based on y １ to y Ｍ and a １,１ to a Ｍ,Ｎ , an image acquisition device that obtains the image of the object excluding the column vector W from the column vector X 2. A light source that outputs light, a photodetector that detects the intensity of the light output from the light source and passing through an object, a spatial light modulator provided on the optical path between the light source and the photodetector that spatially modulates the light intensity, and 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. 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 such that the column vector X has 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, contains only the DC component, a system matrix A in which the 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 is such that the sum of the elements in each row is equal. Based on the system matrix A, 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 y １ to y Ｍ and a １,１ to a Ｍ,Ｎ an image acquisition device that obtains the image of the object excluding the column vector W from the column vector X 3. A light source that outputs light, a photodetector that detects the intensity of the light output from the light source and passing through an 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, and 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. The control unit is such that the AC components of the column vector X with the value of the n-th region (n = 1 to N) of the image of the object being the n-th element x ｎ 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, at the n-th region of the image of the object in 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 in the m-th row and n-th column ｍ,ｎ Based on the system matrix A, 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. The sum of the products of the n-th element w ｎ of W and a ｍ,ｎ is taken as α ｍ , and y' ｍ = y ｍ / α ｍ is taken, and a' ｍ,ｎ = a ｍ,ｎ / α ｍ is taken. Based on y' １ to y' Ｍ and a' １,１ to a' Ｍ,Ｎ , an image acquisition device that obtains the image of the object with the column vector W excluded from the column vector X.

4. A light source that outputs light, a photodetector that detects the intensity of the light output from the light source and passing through an 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, and 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 intensities detected by the photodetector during the periods 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. The control unit sets the value of the nth region (n = 1 to N) of the image of the object as the nth element x ｎ such that the column vector X including the AC component and the 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, based on the system matrix A in which the value corresponding to the intensity modulation amount in the region corresponding to the nth region of the image of the object in the mth pattern (m = 1 to M) among the M patterns is the element a ｍ,ｎ in the mth row and nth column, sequentially sets the spatial intensity modulation patterns of the light by the spatial light modulator to each of the M patterns, and acquires the light intensity y ｍ detected by the photodetector when the mth pattern is set. Let the sum of the products of the nth element w ｎ of W and a ｍ,ｎ be α ｍ , set y' ｍ = y ｍ / α ｍ , set a' ｍ,ｎ = a ｍ,ｎ / α ｍ , and based on y' １ to y' Ｍ and a' １,１ to a' Ｍ,Ｎ , an image acquisition device that obtains the image of the object excluding the column vector W from the column vector X.

5. A light source that outputs light, a photodetector that detects the intensity of the light output from the light source and passing through an object, a spatial light modulator that is provided on the optical path between the light source and the photodetector and spatially modulates the light intensity, and 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. The control unit has a value of the n-th region (n = 1 to N) of the image of the object as the n-th element x ｎ such that 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, at 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 at the m-th row and n-th column ｍ,ｎ Based on the system matrix A, 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. Let the sum of the products of the n-th element w ｎ of W and a ｍ,ｎ be α ｍ , and let y' ｍ = y ｍ - α ｍ . Then, based on y' １ to y' Ｍ and a １,１ to a Ｍ,Ｎ , an image acquisition device that obtains an image of the object with the column vector W excluded from the column vector X is provided.

6. A light source that outputs light, a photodetector that detects the intensity of the light output from the light source and passing through an object, a spatial light modulator provided on the optical path between the light source and the photodetector that spatially intensity-modulates 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. 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 such that the column vector X including 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 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) of the M patterns is the element a at the m-th row and n-th column ｍ,ｎ Based on the system matrix A, 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. The sum of the products of the n-th element w ｎ of W and a ｍ,ｎ is set 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 acquisition device that obtains the image of the object excluding the column vector W from the column vector X.

7. A light source that outputs light, a photodetector that detects the intensity of the light output from the light source and passing through an object, a spatial light modulator provided on the optical path between the light source and the photodetector that spatially intensity-modulates the light, and 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. 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, 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, the intensity modulation amount corresponding to 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 system matrix A. Based on this, 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. The sum of a ｍ,ｎ for n is 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 γ ｍ . Let y' ｍ = y ｍ / β ｍ - γ ｍ , and a' ｍ,ｎ = a ｍ,ｎ / β ｍ . Then, based on y' １ to y' Ｍ and a' １,１ to a' Ｍ,Ｎ , an image acquisition device that obtains an image of the object with the column vector W excluded from the column vector X.

8. The image acquisition device according to any one of claims 1 to 7, wherein 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.

9. The control unit sets 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, as the element a of the m-th row and n-th column of the system matrix A ｍ,ｎ The image acquisition device according to any one of claims 1 to 8 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 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 based on these light intensities and the M patterns. 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 such that 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, ｍ,ｎ a system matrix A in which the 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 Based on the system matrix A, where all 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 １ detected by the photodetector when the m-th pattern is set is obtained, Ｍ and based on y １,１ to y Ｍ,Ｎ and a １,１ to a Ｍ,Ｎ , the image of the object excluding the column vector W 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 light intensity. The method sequentially sets the spatial intensity modulation pattern of the light by the spatial light modulator to each of M different patterns, 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 based on these light intensities and the M patterns. The value of the n-th region (n = 1 to N) of the image of the object is the n-th element x ｎ such that the column vector X has 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, has only a DC component, in 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 in the m-th row and n-th column ｍ,ｎ of the system matrix A. 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 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 obtained. Based on y １ to y Ｍ and a １,１ to a Ｍ,Ｎ , the image of the object excluding the column vector W 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 light intensity, wherein the spatial intensity modulation pattern of the light by the spatial light modulator is sequentially set to each of M different patterns, the light intensity detected by the photodetector is acquired during the period set for each of the M patterns, and the image of the object is obtained based on these light intensities and the M patterns. The value of the n-th region (n = 1 to N) of the image of the object is the n-th element x ｎ of a 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 a 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, ｍ,ｎ Based on a system matrix A in which the 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 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 ｎ detected by the photodetector when the m-th pattern is set is acquired. The sum of the products of the n-th element w ｍ,ｎ of W and a ｍ is defined as α ｍ , and y' ｍ = y ｍ / α ｍ,ｎ is set, and a' ｍ,ｎ = a ｍ / α １ is set. Based on y' Ｍ to y' １,１ and a' Ｍ,Ｎ , the image of the object excluding the column vector W 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 light intensity, wherein the spatial intensity modulation pattern of the light by the spatial light modulator is sequentially set to each of M different patterns, the light intensity detected by the photodetector is acquired during the period set for each of the M patterns, and the image of the object is obtained 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 Let the column vector X whose components are such that it includes an AC component and a DC component, and when a column vector W that is a part of the components included in this column vector X includes only a DC component, at the n-th region of the image of the object in 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, 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. Let the sum of the products of the n-th element w ｎ of W and a ｍ,ｎ be α ｍ , let y' ｍ = y ｍ / α ｍ , and let a' ｍ,ｎ = a ｍ,ｎ / α ｍ . Then, 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. 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 spatial intensity modulation pattern of the light by the spatial light modulator to each of M different patterns, 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 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 of a column vector X such that the AC components of the first AC component and the second AC component that are orthogonal to each other are represented by the sum of the first AC component and the second AC component, and when the AC component of a 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, ｍ,ｎ 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 in the m-th row and n-th column ｍ of a system matrix A. Based on this, 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 ｎ detected by the photodetector when the m-th pattern is set is obtained. Let the sum of the products of the n-th element w ｍ,ｎ of W and a ｍ be α ｍ , and set y' ｍ = y ｍ -α １ . Then, based on y' Ｍ to y' １,１ and a Ｍ,Ｎ , the image of the object excluding the column vector W 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 light intensity, wherein a pattern of spatial intensity modulation of the light by the spatial light modulator is sequentially set to each of M different patterns, the light intensity detected by the photodetector during the period set for each of the M patterns is acquired, and based on these light intensities and the M patterns, an image of the object is obtained. 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 Let the column vector X whose components are such that it 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, at the n-th region of the image of the object in 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, 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. Let the sum of the products of the n-th element w ｎ of W and a ｍ,ｎ be α ｍ , and let y' ｍ = y ｍ - α ｍ . Then, 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. 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 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 of a 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 a 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, ｍ,ｎ 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 in the m-th row and n-th column of a system matrix A. Based on the system matrix A, 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,ｎ detected by the photodetector when the m-th pattern is set is obtained. ｍ The sum of a n,AC2 for n is β ｍ,ｎ , and the value obtained by dividing the sum of the product of the n-th element x ｍ of the second AC component and a ｍ by β ｍ is γ ｍ . Let y' ｍ = y ｍ / β ｍ,ｎ , and a' ｍ,ｎ = a ｍ / β １ . Based on y' Ｍ to y' １,１ and a' Ｍ,Ｎ , an image acquisition method for obtaining the image of the object with the column vector W excluded from the column vector X.

17. The image acquisition method according to any one of claims 10 to 16, wherein 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.

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 defined as the element a of the m-th row and n-th column of the system matrix A ｍ,ｎ The image acquisition method according to any one of claims 10 to 17, wherein the value is set as such.

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