Image reproduction device, hologram recording device, and digital holography device

Abstract

An image reproduction device 6 reproduces an image including N different parameters of a wavelength range or the like, and comprises: a multiplexed hologram acquisition unit 61 for acquiring N to 2N multiplexed holograms obtained by multiplex-recording interference patterns for each parameter; a parameter selection unit 63 for selecting the parameters one by one; a hologram generation unit 64 for generating a calculation hologram including two light waves having the selected parameters from the multiplexed holograms; and a light wave restoration unit 65 for restoring one of the two light waves from the calculation hologram.

Description

[Technical Field]

[0001] The present invention relates to an image reproduction device, a hologram recording device, and a digital holography device. [Background technology]

[0002] Information on optical properties such as wavelength and polarization of light is widely used in various ways, including for identifying molecular composition in optical microscopes, including fluorescence microscopes; obtaining diverse cellular information such as the orientation and localization of biomacromolecules without staining; identifying vital signs such as the health status of living organisms; estimating the degradation state of manufactured goods and materials; identifying the type and properties of substances and materials; and as useful features for object recognition and identification by the naked eye and robot vision. As a method for acquiring optical information, instead of conventional methods using R, G, B color filter arrays or polarizing filters, a multidimensional sensing method has been proposed that uses phase modulation instead of light absorption to improve light efficiency and acquire brighter images, and includes signal processing based on computational coherent multiplexing (see Patent Document 1). Patent Document 1 discloses, for example, a digital holography technology that, as a method for acquiring wavelength information, multiplexes the interference fringes of R, G, and B light using a monochromatic image sensor and reconstructs a three-dimensional image from the obtained multiplexed hologram by signal processing.

[0003] Patent Document 1 assumes that, in order to reconstruct an image containing light in the three wavelength bands of R, G, and B, twice that number (six) of multiplex holograms are prepared, and that the intensity of one of the two light waves forming each interference fringe is independently acquired. In contrast, a technique has been disclosed in which image information for each wavelength band can be obtained from 2N multiplex holograms by using a specific two-stage phase-shift interferometry method and independently acquiring the intensity of one of the light waves forming the interference light for light in the (N-1) wavelength band (see Non-Patent Document 1). The method described in Non-Patent Document 1 makes it possible to apply a two-stage phase-shift interferometry method (see Non-Patent Document 2) that does not require the measurement of the intensity of one of the two light waves forming the interference light. Patent Document 1 and Non-Patent Document 1 assume that, for at least one multiplex hologram, an integer multiple of 2π is given to the phase modulation amount in order to generate the light wave that forms the interference fringe. In contrast, a technique has been proposed in which spectral signal processing is performed with an arbitrary phase modulation amount (Patent Document 2).

[0004] Non-patent document 3 describes a method for separating the object light, which is the first-order diffracted light component, from the zero-order diffracted light intensity distribution and the conjugate image, which is the -1st-order diffracted light component, contained in a recorded hologram, using compressed sensing. This method allows obtaining only the object light from the hologram without using phase-shift interferometry. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 6308594 [Patent Document 2] Japanese Patent Publication No. 2017-076038 [Non-patent literature]

[0006] [Non-Patent Document 1] T. Tahara, et al., “Four-step phase-shifting digital holography simultaneously sensing dual-wavelength information using a monochromatic image sensor”, Journal of Optics (IOP Publishing) Vol. 17, pp. 125707-1-10, 2015 [Non-Patent Document 2] J.-P. Liu and T.-C. Poon, “Two-step-only quadrature phase-shifting digital holography”, Optics Letters Vol. 34, pp. 250-252, 2009 [Non-Patent Document 3] J. Wu, et al., “Single-shot lensless imaging with fresnel zone aperture and incoherent illumination”, Light: Science & Applications Vol. 9, pp. 53-1-11, 2020 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] To reconstruct a single image containing information such as wavelength from multiple holograms, multiple multiple holograms divided temporally or spatially are required, and the number of holograms increases as the number of parameters for the information increases. When the image is divided spatially, the pixels of each multiple hologram become discrete, thus reducing the spatial resolution of the reconstructed image. On the other hand, when the image is divided temporally, i.e., multiple images are taken to acquire multiple holograms, the acquisition time for each image increases, reducing the temporal resolution. Furthermore, if information such as wavelength band subdivision or polarization is obtained, the number of parameters increases, further reducing the spatial or temporal resolution. Therefore, in digital holography technology, there is a need for image reconstruction using fewer multiple holograms. Patent documents 1 and 2 disclose a technique for reconstructing an image from (2N+1) multiple holograms, where N is the number of parameters. However, for example, to reconstruct an image containing three wavelength bands (R, G, and B) (N=3), it is necessary to acquire 7 multiple holograms. Patent Document 1 and Non-Patent Document 1 disclose techniques for reconstructing an image from 2N multiple holograms. However, when recording multiple holograms, it is necessary to separately record the intensity of the light wave for each parameter, resulting in a spatial or temporal resolution equivalent to recording at least (2N+1) images. Therefore, there is room for improvement in these techniques.

[0008] The present invention has been made in view of the above-mentioned problems, and aims to provide an image reproduction device capable of reproducing an image with high spatial and temporal resolution that includes optical property information, a hologram recording device for acquiring multiple holograms for reproducing the image, and a digital holography device equipped with the same. [Means for solving the problem]

[0009] The image reproduction device according to the present invention has a wavelength band, polarization direction, and The field of view was divided into multiple sections.An apparatus for reconstructing an image containing N different types of light for each of the parameters or combinations of parameters for any one or more optical information in a measurement area, from N to 2N multiplex holograms in which at least one of the 2N types of light waves that formed the N patterns of interference fringes is recorded in multiplexed records, with each parameter having one interference fringe formed by two light waves with different phases, for a total of N patterns, and recorded in temporally or spatially divided, wherein the phase of at least one of the light waves that formed the N patterns of interference fringes is different from that of the other, the apparatus comprising a parameter selection unit that selects one parameter at a time N times from the N parameters, and when the parameter selection unit selects a parameter, at least The system comprises a hologram generation unit that generates a computational hologram containing the two light waves by removing interference fringes of (N-1) patterns other than those formed by the two light waves having the selected parameters from a single multi-layer hologram, and a light wave restoration unit that restores one of the two light waves from the computational hologram generated by the hologram generation unit, wherein, after the light wave restoration unit has restored one or more light waves, the hologram generation unit generates a computational hologram containing two light waves having different parameters from the restored light waves by using the light wave restoration unit and the calculation used to restore the light waves Math Ho The configuration uses at least one program.

[0010] Another image reproduction device according to the present invention includes a wavelength band, polarization direction, and The field of view was divided into multiple sections.An image reproduction device that reproduces an image containing N different types of light for each of the parameters or combinations of parameters for any one or more optical information in a measurement area from 2N multiplex holograms, each of which has one interference fringe formed by two light waves with different phases for each parameter, and which is recorded in a total of N patterns and divided in time or space, wherein, of the 2N multiplex holograms, excluding the 2N multiplex hologram whose phase differs for at least one of the 2N types of light waves that formed the N patterns of interference fringes, (2N-1) multiplex holograms whose phase differs for at least one of the 2N types of light waves from each other, each of which has two light waves that formed the (N-1) patterns of interference fringes other than the Nth interference fringe The system includes: a first light wave reconstruction unit that reconstructs a total of (N-1) types of light waves; a first hologram generation unit that uses the light waves reconstructed by the first light wave reconstruction unit to remove interference fringes of (N-1) patterns other than the N interference fringes from at least one of the multiple holograms other than the second N multiple hologram to generate a first computational hologram; a second hologram generation unit that uses the light waves reconstructed by the first light wave reconstruction unit to remove interference fringes of (N-1) patterns other than the N interference fringes from the second N multiple hologram to generate a second computational hologram; and a second light wave reconstruction unit that uses the phase shift method to reconstruct one of the two light waves that formed the N interference fringes from the first computational hologram and the second computational hologram.

[0011] The hologram recording apparatus according to the present invention records the wavelength band, polarization direction, and light wave of an object. The field of view was divided into multiple sections.The apparatus includes: an optical wave generation means that generates N types of optical waves, each with a different phase for each of the parameters or combinations thereof for one or more optical pieces of information in a measurement area; and an image sensor that receives the optical waves generated by the optical wave generation means and multiple-records interference fringes formed by two optical waves with the same parameters but different phases as multiple holograms, wherein the two or more patterns of interference fringes are recorded in a temporal or spatial division, and the optical waves are configured such that at least one of the optical waves forming the two or more patterns of interference fringes recorded in each of the multiple holograms has a different phase.

[0012] The digital holography apparatus according to the present invention comprises the hologram recording apparatus and the image reproduction apparatus described above. [Effects of the Invention]

[0013] According to the image reproduction apparatus, hologram recording apparatus, and digital holography apparatus of the present invention, it is possible to record a minimum number of holograms with high light utilization efficiency and to reproduce images with high spatial and temporal resolution from the minimum number of recorded holograms. [Brief explanation of the drawing]

[0014] [Figure 1] This is a schematic diagram illustrating the configuration of a digital holography apparatus according to an embodiment of the present invention. [Figure 2] This is a schematic enlarged view of a portion of the spatial optical phase modulator of a hologram recording apparatus according to an embodiment of the present invention. [Figure 3] This is a block diagram of the calculation unit of a digital holography apparatus for illustrating the configuration of an image reproduction apparatus according to the first embodiment of the present invention. [Figure 4] This is a flowchart illustrating the image reproduction method according to the first embodiment of the present invention. [Figure 5]This is a block diagram of the calculation unit of a digital holography apparatus for illustrating the configuration of an image reproduction apparatus according to a second embodiment of the present invention. [Figure 6] This is a flowchart illustrating an image reproduction method according to a second embodiment of the present invention. [Figure 7] This is a schematic diagram illustrating the configuration of a digital holography apparatus according to a first modified embodiment of the present invention. [Figure 8] This is a schematic diagram of a digital holography apparatus according to a second modified embodiment of the present invention. [Figure 9] This is a schematic diagram illustrating the configuration of a digital holography system equipped with a fluorescence microscope. [Figure 10] This is a schematic diagram illustrating the configuration of a digital holography system equipped with a quantitative phase microscope. [Figure 11] This is an image of an object used as a subject for simulation in an embodiment of the digital holography apparatus according to the present invention. [Figure 12] Figure 11 is a photograph of a multi-hologram of the object shown, simulated using the digital holography apparatus shown in Figure 7, with a spherical wave focal length of 50 mm. [Figure 13] Figure 12 is a photograph of an image reconstructed from a multi-layered hologram. [Figure 14] Figure 11 is a photograph of a multi-hologram of the object shown, simulated using the digital holography apparatus shown in Figure 7, with a spherical wave focal length of 340 mm. [Figure 15] Figure 14 is a photograph of an image reconstructed from a multi-layered hologram. [Figure 16] This is a photograph of a multiple hologram of a fluorescent sample, obtained by imaging a fluorescent sample using an embodiment of the digital holography apparatus according to the present invention. [Figure 17A] Figure 16 shows photographs of images reconstructed from the multi-layered hologram, separated by wavelength. [Figure 17B] Figure 16 shows images of wavelength-specific images at a depth of 75 μm from the imaging plane, reconstructed from the multi-layered hologram. [Figure 17C]Figure 16 shows images of wavelength-specific images at a depth of 106 μm from the imaging plane, reconstructed from a multi-layered hologram. [Figure 18A] Figure 16 is a photograph of an image reconstructed from a multi-layered hologram. [Figure 18B] Figure 16 shows a photograph of the image at a depth of 75 μm from the imaging surface, reconstructed from the multi-layered hologram. [Figure 18C] Figure 16 shows a photograph of the image reconstructed from the multi-layered hologram at a depth of 106 μm from the imaging plane. [Modes for carrying out the invention]

[0015] Embodiments for implementing the image reproduction apparatus, hologram recording apparatus, and digital holography apparatus according to the present invention will be described with reference to the drawings. The apparatus and its elements shown in the drawings may have their size and positional relationships exaggerated, and their shapes may be simplified, in order to clarify the explanation. In the following description, identical or similar elements will be denoted by the same reference numeral, and their descriptions will be omitted as appropriate.

[0016] [First Embodiment] As shown in Figure 1, the digital holography apparatus 10 according to an embodiment of the present invention comprises a hologram recording apparatus equipped with a spatial light phase modulator (light wave generation means) 1 and an image sensor 2, and a computer 50 incorporating an image reproduction apparatus 6 (see Figure 3) according to the first embodiment of the present invention. The hologram recording apparatus further comprises a recording control unit 5 (see Figure 3) built into the computer 50. The computer 50 can be a commercially available personal computer (PC) or the like. The digital holography apparatus 10 receives light (light waves) L from an object (subject) OBJ. OBJ The hologram recording device records N multiple holograms I1, I1, ..., I N The image is recorded as such, and the image reproduction device 6 reproduces multiple holograms I1, I2, ..., I N Recreate a multicolor 3D image of the object OBJ.

[0017] (Hologram recording device) The hologram recording device of the digital holography apparatus 10 constitutes a self-interferometer having an in-line optical system, and transmits light L from the object OBJ. OBJ The spatial light phase modulator 1, upon receiving the incident light, generates light waves La and Lb with different phases, and the image sensor 2 captures the interference fringes formed by the light waves La and Lb as a hologram. OBJ To generate the hologram, the hologram recording device (digital holography device 10) further includes a light source (not shown) that irradiates the object OBJ with light. In this embodiment, light L OBJ The light source is visible light, natural light with random polarization directions, and does not necessarily have to be coherent light. Therefore, the light source can be a common lighting device such as a white LED (light-emitting diode), fluorescent lamp, halogen lamp, mercury lamp, or sunlight. Furthermore, the light source can also be a phosphor or self-luminous material containing autofluorescence, and these can also be used as object objects (OBJs). In addition, by applying a light source that combines monochromatic light sources such as LEDs of each color (R (red), G (green), and B (blue)), a multi-layer hologram that can reproduce images with high color reproduction can be obtained.

[0018] The spatial light phase modulator 1 is formed by two-dimensionally arranging optical phase modulation elements that shift the phase of incident light by a shift amount corresponding to its wavelength. For light of the same wavelength, the shift amount varies depending on the cell (optical phase modulation element). Such a spatial light phase modulator 1 having wavelength dependency is preferably a liquid crystal spatial light modulator. However, a liquid crystal spatial light modulator modulates the phase of light in a specific polarization direction. Therefore, conventionally, as shown in FIG. 9 as an example, a polarizer 47a is disposed on the light incident side of the spatial light phase modulator 11A, and light (linear polarized light) in one polarization direction is incident on the spatial light phase modulator 11A. With such a configuration, part of the light is absorbed by the polarizer 47a, resulting in a decrease in the light utilization efficiency. In contrast, in the present embodiment, the spatial light phase modulator 1 includes two transmissive liquid crystal spatial light modulators, a first spatial light phase modulator (first spatial light phase modulation unit) 11 and a second spatial light phase modulator (second spatial light phase modulation unit) 12, which are stacked. The first spatial light phase modulator 11 and the second spatial light phase modulator 12 can be transmissive liquid crystal spatial light modulators mounted on a liquid crystal display (LCD) or the like.

[0019] The first spatial light phase modulator 11 and the second spatial light phase modulator 12 are provided with the same number of optical phase modulation elements arranged at the same pixel (optical phase modulation element) pitch, but the polarization directions of the light to be phase-modulated are orthogonal to each other. The polarization direction of the light to be phase-modulated can be set by the surface shape of the alignment film of the spatial light phase modulators 11 and 12. Here, as shown in FIG. 2, the optical phase modulation elements 11a and 11b of the first spatial light phase modulator 11 disposed on the light incident side of the light L OBJ modulate the light (y-polarized light) L polarized in the y direction (90° direction), and the optical phase modulation elements 12a and 12b of the second spatial light phase modulator 12 modulate the light (x-polarized light) L0 polarized in the x direction (0° direction). Also, the first and second spatial light phase modulators 11 and 12 are each provided with two types of optical phase modulation elements 11a, 12a and optical phase modulation elements 11b, 12b having different phase shift amounts arranged randomly. However, the optical phase modulation element 11a and the optical phase modulation element 12a, and the optical phase modulation element 11b and the optical phase modulation element 12b are each in a plane (light L OBJ ​​They are positioned at the same location when viewed from the incident plane (viewed along the optical axis). Furthermore, the phase shift amount is set to α for both optical phase modulation elements 11a and 12a, and to α' for both optical phase modulation elements 11b and 12b (α≠α'). The phase shift amount can be controlled by the magnitude of the applied voltage to each optical phase modulation element. In this embodiment, as will be described later, the image sensor 2 records multiple times in time division to obtain one image, and the spatial optical phase modulator 1 switches the phase shift amount of each cell accordingly. For this purpose, it is preferable that the first and second spatial optical phase modulators 11 and 12 have a fast response speed.

[0020] With this configuration, light L with random polarization directions is incident on the spatial light phase modulator 1. OBJ (In Figure 2, x-polarized L0 and y-polarized L 90 The (represented by) first enters the first spatial optical phase modulator 11, and the y-polarized L 90 Only the light is phase-modulated by the optical phase modulation elements 11a and 11b with shift amounts α and α', respectively. Therefore, the light emitted from the first spatial optical phase modulator 11 is x-polarized L0 and y-polarized L 90 The phases are shifted between them. Next, the light is incident on the second spatial optical phase modulator 12, and only the x-polarized L0 is phase-modulated by the optical phase modulation elements 12a and 12b with shift amounts α and α', respectively. As a result, the light emitted from the second spatial optical phase modulator 12 (spatial optical phase modulator 1) is divided into x-polarized L0 and y-polarized L 90As the phases are restored to their original state, the amount of phase shift differs between the light transmitted through the optical phase modulation elements 11a and 12a and the light transmitted through the optical phase modulation elements 11b and 12b, resulting in a phase difference of |α-α'|. Therefore, the spatial optical phase modulator 1 can perform phase modulation on each of the two-dimensionally arranged cells for light of all polarization directions without polarization dependence. In other words, the spatial optical phase modulator 1 has cells 1a, formed by stacking optical phase modulation elements 11a and 12a, and cells 1b, formed by stacking optical phase modulation elements 11b and 12b, arranged randomly, with cell 1a changing the phase by a shift amount α and cell 1b changing the phase by a shift amount α'. Ideally, the distance between the first spatial optical phase modulator 11 and the second spatial optical phase modulator 12 is 0, and therefore, it is preferable that the first spatial optical phase modulator 11 and the second spatial optical phase modulator 12 are stacked in close contact, and it is even more preferable that the liquid crystal layers, which are the respective phase modulation parts, are placed facing each other.

[0021] Light transmitted through the optical phase modulation elements 11a and 12a (cell 1a) of the spatial optical phase modulator 1 forms a spherical wave, the optical wave La, and light transmitted through the optical phase modulation elements 11b and 12b (cell 1b) forms a spherical wave, the optical wave Lb. In Figure 1, the optical waves La and Lb are shown with their propagation directions shifted to make them easier to distinguish, but the direction and shape are not limited to this. It is preferable that the spatial optical phase modulator 1 provides a non-aliased spherical wave phase distribution to cell 1a or cell 1b, which is the region that generates one of the two optical waves. By providing a non-aliased spherical wave phase distribution, the spatial optical phase modulator 1 functions as a lens, and since no optical waves of unwanted orders are generated, a higher optical utilization efficiency can be obtained than when a diffractive lens is used. Furthermore, it is preferable that the spatial optical phase modulator 1 is arranged so that the number of cells 1a and 1b is equal or close to equal. This ensures that the optical waves La and Lb have equal intensity (intensity ratio of 1) or close to equal intensity. Here, as described above, the optical phase modulation elements 11a, 11b, 12a, and 12b of the spatial optical phase modulator 1 are wavelength-dependent, so the light emitted from the spatial optical phase modulator 1 forms two light waves for each wavelength band. In this embodiment, two light waves for each of the R, G, and B wavelength bands, for a total of six light waves, are emitted from the spatial optical phase modulator 1. In the digital holography apparatus 10 according to this embodiment, the number of wavelength bands (number of parameters) can be set arbitrarily, and may be 2, or it may be subdivided into 4 or more. For simplicity, in Figure 2, one wavelength of light L0, L 90 Figure 1 shows two light waves, La and Lb, which are the same wavelength (wavelength band). Hereafter, in this specification, two light waves refer to two light waves that have the same parameters (in this case, wavelength band) but different phases.

[0022] The image sensor 2 converts the incident light into an electrical signal for each pixel in its two-dimensional array and outputs it. In this embodiment, the image sensor 2 receives L from the object OBJ. OBJTo image light in the R, G, and B wavelength bands without distinction, a monochromatic image sensor sensitive to all of these wavelengths is used. Specifically, the image sensor 2 may be a complementary metal-oxide semiconductor (CMOS) image sensor or a charge-coupled device (CCD) image sensor equipped with photodiodes made of Si as pixels, which have a wide spectral sensitivity including the visible region. Alternatively, the image sensor 2 can be an array of commercially available photodetectors such as electron multiplier tubes. Furthermore, it is preferable that the number of pixels in the image sensor 2 is equal to or greater than the number of pixels (cells) of the spatial light phase modulator 1 (first and second spatial light phase modulators 11, 12). In addition, in this embodiment, it is preferable that the image sensor 2 has a fast response speed, similar to the first and second spatial light phase modulators 11, 12.

[0023] As shown in Figure 3, the recording control unit 5 includes a spatial light phase modulator control unit 51 that drives and controls the spatial light phase modulator 1 (first and second spatial light phase modulators 11 and 12), and an image sensor control unit 52 that drives and controls the image sensor 2. Such a recording control unit 5 consists of a CPU (Central Processing Unit) that performs calculations, and flash memory or RAM (Random Access Memory) that stores programs for the calculations, and is built into the computer 50.

[0024] (Image reproduction device) The image reproduction device 6 reproduces an image containing N different patterns of light, each containing N different patterns of interference fringes formed by two light waves with different phases for each parameter, and is recorded temporally or spatially divided. This is done by reproducing N to 2N multiplex holograms, each containing N different phases of at least one of the 2N types of light waves that form the N patterns of interference fringes. As shown in Figure 3, the image reproduction device 6 comprises a multiplex hologram acquisition unit 61, a parameter selection unit 63, a hologram generation unit 64, and a light wave reconstruction unit 65. The image reproduction device 6 further comprises a storage unit 62, an amplitude / phase calculation unit 68, and an image reproduction unit 69. These elements of the image reproduction device 6 consist of a CPU, flash memory, etc., similar to the recording control unit 5 of the hologram recording device, and are built into the computer 50 together with the recording control unit 5 because they transmit and receive signals with the recording control unit 5.

[0025] The multiple hologram acquisition unit 61 acquires N to 2N multiple holograms I1, I2, ... recorded by the image sensor 2 from the image sensor control unit 52 of the hologram recording device. The multiple hologram acquisition unit 61 writes the acquired multiple holograms I1, I2, ... to the storage unit 62 and notifies the parameter selection unit 63 that the writing is complete. The memory unit 62 stores multiple holograms I1, I2, ... and is composed of a general storage medium such as semiconductor memory.

[0026] The parameter selection unit 63 sequentially selects parameters. The parameter selection unit 63 outputs the selected parameters to the hologram generation unit 64. The parameter selection unit 63 sequentially selects parameters until there are N parameters to select, and outputs them to the hologram generation unit 64.

[0027] The hologram generation unit 64 generates a hologram (computational hologram) containing two light waves having the parameters selected by the parameter selection unit 63 from the multiple holograms I1, I2, ... stored in the memory unit 62. The hologram generation unit 64 outputs the generated hologram to the optical reconstruction unit 65. The hologram generation unit 64 generates holograms (computational holograms) equal to the number of parameters selected by the parameter selection unit 63.

[0028] The light wave reconstruction unit 65 reconstructs one of the two light waves from the hologram (computational hologram) generated by the hologram generation unit 64. The light wave reconstruction unit 65 reconstructs light waves for the number of parameters selected by the parameter selection unit 63. The optical wave reconstruction unit 65 outputs the reconstructed optical wave to the amplitude / phase calculation unit 68.

[0029] The amplitude / phase calculation unit 68 calculates the amplitude and phase at an arbitrary depth for each light wave restored by the light wave restoration unit 65. The amplitude / phase calculation unit 68 outputs the calculated amplitude and phase at any depth to the image playback unit 69. The image playback unit 69 reproduces a three-dimensional image from the amplitude and phase at an arbitrary depth calculated by the amplitude / phase calculation unit 68. The specific operation of the image reproduction device 6 will be explained in detail in the image reproduction method described later.

[0030] (Hologram recording method) The hologram recording method using the hologram recording device of the digital holography apparatus 10 according to this embodiment will be described with reference to Figure 1. As described above, light L from the object OBJ OBJThe light passes through the spatial light phase modulator 1 and enters the image sensor 2 as two light waves, one for each of the R, G, and B wavelength bands. These six light waves form interference fringes on the imaging surface of the image sensor 2, with two light waves of the same wavelength band forming interference fringes, that is, three patterns of interference fringes for each of the R, G, and B colors overlap. The image sensor 2 captures these three patterns of interference fringes together and records them as a multiple hologram I. The multiple hologram I is appropriately represented as multiple hologram I(x,y) (where x and y are planar coordinates). The image sensor 2 continues to take images a predetermined number of times. As a result, a total of 3 to 6 multiple holograms I1, I2, ... are recorded. At this time, the phase shift amounts α and α' of at least one of the optical phase modulation elements 11a, 12a (cell 1a) and optical phase modulation elements 11b, 12b (cell 1b) of the spatial optical phase modulator 1 (first and second spatial optical phase modulators 11, 12) are changed in accordance with the timing of each imaging, thereby changing the phase difference between the two optical waves. Through this operation, the multiple holograms I1, I2, ... become different from each other. The number of multiple holograms required for image reconstruction varies depending on the image reconstruction method, as will be described later. Furthermore, in order to simplify the calculations in image reconstruction, it is preferable that the intensity ratio of the two optical waves forming each interference fringe of the multiple hologram I is 1 or close to it, as described above.

[0031] Here, the phase shift amount α' due to cell 1b is kept constant, and the light wave from cell 1b is set to be a non-aliased spherical wave as described above, while the phase shift amount α due to cell 1a is changed. At that time, α for each time is stored for each parameter (wavelength band), and the phase shift amount α' for light in at least one wavelength band (the Nth parameter) is also stored. Furthermore, for the light of at least the Nth parameter, the phase shift amounts α, α' and the phase difference between the two light waves from cell 1a or cell 1b during each imaging are controlled as a result of calculations using multiple holograms I1, I2, ... to a value that allows for a hologram of only a single parameter's light wave, or a hologram of a single parameter's light wave and a zero-order diffracted light intensity distribution. Details will be explained in the image reconstruction method below. The Nth (third) parameter is set to the red wavelength band. The values ​​of each phase shift amount are stored in the memory unit of the spatial light phase modulator control unit 51 (computer 50).

[0032] (Image reproduction method) The image reproduction method by the image reproduction device 6 of the digital holography apparatus 10 according to an embodiment of the present invention (hereinafter, the image reproduction method according to the first embodiment of the present invention) will be described with reference to Figure 4. First, the multiple hologram acquisition unit 61 receives from the image sensor control unit 52 of the hologram recording apparatus the N multiple holograms I1, I2, ..., I recorded by the image sensor 2. N The first hologram is obtained (multiple hologram acquisition step S1). Next, the parameter selection unit 63 selects the Nth parameter from the N parameters (parameter selection step S21). Then, the hologram generation unit 64 generates multiple holograms I1, I2, ..., I containing two light waves having the selected Nth parameter (calculated holograms). NThe hologram is generated from the generated hologram (hologram generation step S22), and the optical wave reconstruction unit 65 reconstructs one of the two optical waves from the generated hologram (optical wave reconstruction step S23). Steps S21 to S23 are repeated until all parameters have been selected (S24: NO). In the second parameter selection step S21, the (N-1)th parameter is selected, and steps S22 and S23 reconstruct the optical wave having the (N-1)th parameter. Once all parameters have been selected (S24: YES), that is, once optical waves having all parameters have been reconstructed, the amplitude / phase calculation unit 68 calculates the amplitude and phase at an arbitrary depth for each reconstructed optical wave (amplitude / phase calculation step S3), and the image reproduction unit 69 reconstructs a three-dimensional image (image reproduction step). The following describes in detail the method using N multiple holograms, using the case of three wavelength bands R, G, and B (N=3) as an example for each step.

[0033] Here, holograms obtained using a self-interferometer or an interferometer that images phase objects can be expressed by the following equation (1). In equation (1), I(x,y) is an arbitrary hologram recording one pattern of interference fringes. A(x,y) is the amplitude distribution of the light wave on the recording (imaging) plane, φ(x,y) is the phase difference distribution of the two light waves, and M is the intensity ratio of the two light waves (1:M).

number

[0034] On the other hand, the j-th multiplex hologram I, which records N patterns of interference fringes multiplexed together, is recorded by the hologram recording device constituting the self-interferometer according to this embodiment and by the two-beam interferometer that measures phase objects. j (x,y) can be expressed by the following equation (2). A i M i φ is the amplitude-intensity ratio of light in the i-th parameter (wavelength band). i This is the phase difference between the two light waves of the i-th parameter in the first multiple hologram I1(x,y). Also, α ij This is the j-th multi-layer hologram I jThis is the relative phase shift between two light waves of the i-th parameter at (x,y).

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[0035] According to a compressed sensing algorithm (see Non-Patent Literature 3), it is known that the amplitude distribution of the light wave on the recording surface and the phase difference distribution of two light waves can be extracted from a hologram that records one pattern of interference fringes. Specifically, only A(x,y) and φ(x,y) from the third term on the right-hand side of equation (1) are extracted. This makes it possible to selectively extract light waves of each wavelength band from three multiplexed holograms (I1, I2, I3) that have interference fringes of three wavelength bands recorded on them.

[0036] To reconstruct an image from N multiple holograms, the phase shift amount α in each is required. ij Set the following: Phase shift amount α in the first multiple hologram I1. i1 (α) is set to 0 for each parameter (wavelength band). i1 (=0). And the phase shift amount α of the i-th parameter (i=1,2,...,N-1) excluding the Nth parameter. ij This is the multi-layered hologram I from the 2nd to the (N-1)th image. j In each of the (j=2~N-1) cases, α ij = 2(j-1)π / 2 i-1 And the Nth multi-layer hologram I N In this case, an integer multiple of 2π, preferably α ij Let = ±(Ni)2π. On the other hand, the phase shift amount α of the Nth parameter. Nj This is the multi-layered hologram I from the 2nd to the (N-1)th image. j In this case, the value is arbitrary, and the Nth multi-hologram I N In this case, let it be any value other than an integer multiple of 2π. Since N=3, α 11 =α 21 =α 31 =0, α 12 =2π, α 22 =2π / 2=π, α 13 = 4π or -4π, α23 It is set to =2π or -2π, and also any α 32 , and any α except integer multiples of 2π 33 These are given. These phase shift amounts α ij and the phase difference φ of the Nth parameter N This information is provided from the spatial light phase modulator control unit 51 to the image regeneration device 6. As a result, the red wavelength band is selected as the Nth (third) parameter to be selected for the first time (parameter selection step S21), and A3(x,y) and φ3(x,y) are extracted in the following procedure. As mentioned above, the parameters are selected in the order i=N, N-1, ..., 2, 1 from the first time.

[0037] As mentioned above, the phase shift amount α in the first multiple hologram I1 11 ,α 21 ,α 31 (α) is 0 in each wavelength band to indicate the reference phase shift amount. i1 =0). In the second multiple hologram I2 (j=2), i=1 to N-1, i.e., the phase shift amount α of light in the blue and green wavelength bands. 12 ,α 22 These values ​​are 2π and 2π / 2 with respect to wavelength, respectively, and i=N, i.e., the phase shift amount α of light in the red wavelength band. 32 is an arbitrary value. And α is the amount of phase shift of light in the blue and green wavelength bands in the third multiple hologram I3. 13 ,α 23 α is an integer multiple of 2π, while α is the phase shift amount of light in the red wavelength band. 33 is a value other than an integer multiple of 2π. Each of these multiple holograms I1, I2, and I3 can be expressed as shown in equations (3) to (5) below. 0th (x,y) is the sum of the zero-order diffraction intensity distributions for each parameter.

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[0038] To simplify the calculations, we approximate M1 ≈ M2 ≈ M3 ≈ M. Also, α 32=π / 2, α 33 By setting to an odd multiple of π, equation (6) is obtained from equations (3) and (5). From equation (6), it is determined that a hologram consisting only of the interference fringes of the red light wave, which is the third parameter, is extracted (hologram generation step S22).

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[0039] From the hologram extracted by equation (6), A3(x,y) and φ3(x,y) can be extracted using the compressed sensing algorithm (see Non-Patent Document 3) as described above (optical wave reconstruction step S23).

[0040] For the second time, the parameter to be selected (i=N-1=2) is, for example, the green wavelength band (parameter selection step S21), and A2(x,y) and φ2(x,y) are extracted. Here, for the two multiple holograms I1 and I2 other than multiple hologram I3, terms containing A3(x,y), cosφ3(x,y), and sinφ3(x,y) (=cos[φ3(x,y)-π / 2]) are removed from each, and then subtracted in the same way as the first time, from equation (7) below, a hologram containing only the interference fringes of the green light wave, which is the second parameter, is extracted (hologram generation step S22). Then, A2(x,y) and φ2(x,y) are extracted from the extracted hologram in the same way (light wave reconstruction step S23).

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[0041] Finally (for the third time), by selecting the blue wavelength band and removing terms containing A3(x,y), cosφ3(x,y), sinφ3(x,y) (=cos[φ3(x,y)-π / 2]), A2(x,y), cosφ2(x,y), sinφ2(x,y) (=cos[φ2(x,y)-π / 2]) from a single multiple hologram I1, a hologram containing only the interference fringes of blue light waves is extracted (hologram generation step S22). Then, A1(x,y) and φ1(x,y) are extracted from the extracted hologram (light wave reconstruction step S23).

[0042] For each wavelength band, the amplitude and phase distribution at an arbitrary depth are calculated from the light waves on the imaging surface of the image sensor 2 (amplitude / phase calculation step S3). As a calculation method, known diffraction integral calculation algorithms, image reconstruction algorithms using compressed sensing, and image reconstruction algorithms using machine learning such as deep learning can be applied. From the amplitude and phase distributions of the light waves in each wavelength band obtained for each depth, a two-dimensional or three-dimensional image at that depth can be reconstructed (image reconstruction step S4).

[0043] Note that if N=2, α i1 =0, α 12 Since =π is given, the two multiple holograms I1 and I2 can be expressed by equations (3) and (4), respectively, and the light waves can be reconstructed in the same way as in the case of N=3. In addition, in the light wave reconstruction step S23, in addition to using a compressed sensing algorithm, a known machine learning-based estimation or an unwanted light removal algorithm using iterative calculation processing can be used.

[0044] According to the image reproduction method of this embodiment, an image can be reproduced from N multiple holograms, the same number as the number of parameters N. On the other hand, when recording multiple holograms, it is necessary to set the light wave of each parameter to a predetermined phase shift amount with respect to the wavelength. Therefore, if the number of parameters N increases, it may become difficult to generate light waves depending on the type of information, such as the wavelength band. To address this, by acquiring up to 2N multiple holograms, the phase shift amount can be arbitrarily set, excluding the light waves of some parameters. Below, a modified image reproduction method using the image reproduction device according to an embodiment of the present invention (an image reproduction method according to a modified version of the first embodiment of the present invention) will be described.

[0045] (Variation example: Image reproduction method) In this modified example, the phase shift amount in each wavelength band is set to 0 in the first multiple hologram I1 (α i1 Except for setting =0, the other 2 to 2N multiple holograms I2, I3, ..., I 2N In this case, all values ​​can be set to any value. When N=3, for each of the six multi-holograms I1, I2, I3, I4, I5, I6, the second term α on the right side is set as shown in equations (8) to (13) below. i The coefficients of (x,y) are -3, -2, -1, +1, +2, +3.

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[0046] Equation (8) and (13) yield equation (14), equation (9) and (12) yield equation (15), and equation (10) and (11) yield equation (16). From the three simultaneous equations (14), (15), and (16), we can find A3(x,y) 2 Since sinφ3(x,y) can be extracted (hologram generation step S22), the red light wave can be reconstructed in the same manner as in the above embodiment (light wave reconstruction step S23). Next, by subtracting in the same manner as the first time, A2(x,y) 2The sinφ2(x,y) can be extracted (hologram generation step S22), and the green light wave can be reconstructed (light wave reconstruction step S23). Furthermore, the blue light wave can then be reconstructed in the same manner as in the above embodiment.

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[0047] According to the image reproduction method of this modified example, an image can be reproduced by generating light waves that form interference fringes for 2N multiple holograms (twice the number of parameters N) with an arbitrary phase shift amount. Furthermore, by setting the phase shift amount of some of the light waves to a value corresponding to the wavelength of the light wave, as in the above embodiment, the number of multiple holograms can be reduced to (2N-1) or less.

[0048] According to the first embodiment and its modified image reconstruction method, an image containing light with a number of parameters N can be reconstructed from 2N or fewer, with a minimum of N, multiple holograms. This embodiment and its modified image reconstruction method can be applied to multiple holograms recorded by any interferometer, such as a two-beam interferometer. On the other hand, since each parameter's light wave is reconstructed using a compressed sensing algorithm, the computation time is proportional to the number of parameters N. Therefore, by acquiring 2N multiple holograms, the image can be reconstructed at high speed. The image reconstruction apparatus and image reconstruction method according to the second embodiment of the present invention will be described below.

[0049] [Second Embodiment] (Image reproduction device) The image reproduction device 6A according to the second embodiment of the present invention reproduces an image containing N different types of light, each containing one or more parameters or combinations of parameters for each of the optical information such as wavelength band, polarization direction, and measurement area, from 2N multiplexed holograms, each of which is recorded by multiplexing one interference fringe formed by two light waves with different phases for each parameter, and is divided temporally or spatially. As shown in Figure 5, the image reproduction device 6A comprises a multiplexed hologram acquisition unit 61, a first light wave reconstruction unit 66a, a first hologram generation unit 67a, a second hologram generation unit 67b, and a second light wave reconstruction unit 66b. The image reproduction device 6A further comprises a storage unit 62, an amplitude / phase calculation unit 68, and an image reproduction unit 69. These elements, like those of the image reproduction device 6 according to the first embodiment, consist of a CPU and flash memory built into the computer 50.

[0050] The first light wave reconstruction unit 66a processes the (N-1) light waves, each having the first to (N-1) parameters, into multiple holograms I1, I2, ..., I stored in the memory unit 62. 2N-1 It is generated from. The first optical wave reconstruction unit 66a outputs the reconstructed optical wave to the first hologram generation unit 67a, the second hologram generation unit 67b, and the amplitude / phase calculation unit 68.

[0051] The first hologram generation unit 67a uses the light waves restored by the first hologram generation unit 67a to generate multiple holograms I1, I2, ..., I stored in the memory unit 62. 2N-1 This method generates a hologram (first computational hologram) containing two light waves with the Nth parameter from at least one of the images. The first hologram generation unit 67a outputs the generated hologram to the second optical wave reconstruction unit 66b.

[0052] The second hologram generation unit 67b uses the light waves restored by the first hologram generation unit 67a to generate the multiple hologram I stored in the memory unit 62. 2N From this, a hologram (second computational hologram) containing two light waves with the Nth parameter is generated. The second hologram generation unit 67b outputs the generated hologram to the second optical wave reconstruction unit 66b.

[0053] The second light wave reconstruction unit 66b reconstructs one of the two light waves from the holograms generated by the first hologram generation unit 67a and the second hologram generation unit 67b. The second optical wave reconstruction unit 66b outputs the reconstructed optical wave to the amplitude / phase calculation unit 68. The specific operation of the image reproduction device 6A will be explained in detail in the image reproduction method described later.

[0054] The hologram recording device of the digital holography apparatus 10 equipped with such an image reproduction device 6A records 2N multiple holograms I1, I2, ..., I 2N The following is recorded. Here, for the Nth parameter light wave (for example, a light wave in the blue wavelength band), (2N-1) multiple holograms I1, I2, ..., I 2N-1 In this case, the phase shift amount α Nj Let be an integer multiple of 2π (an even multiple of π), and one of them is a multi-layer hologram I k In α Nk Let = 0. Also, multiple hologram I 2N In this case, the phase shift amount α N2N Let be a value other than an integer multiple of π. On the other hand, the light wave of the other 1st to (N-1) parameters is α Nk Multiple hologram I with =0 k Regarding this, α is used to indicate the reference phase shift amount. ik Set = 0, and for all other cases, each will have an arbitrary phase shift amount α. ij Let's assume that.

[0055] (Image reproduction method) The image reproduction method by the image reproduction device 6A of the digital holography apparatus 10 according to this embodiment (hereinafter, the image reproduction method according to the second embodiment of the present invention) will be described with reference to Figure 6. First, the multiple hologram acquisition unit 61 receives from the image sensor control unit 52 of the hologram recording apparatus the 2N multiple holograms I1, I2, ..., I recorded by the image sensor 2. 2Nto obtain (multiple hologram acquisition step S1A). Next, the first light wave restoration unit 66a restores (N - 1) light waves each having the first to (N - 1) parameters from the (2N - 1) multiple holograms I1, I2, …, I 2N-1 (first light wave restoration step S25). Next, using the restored (N - 1) light waves, the first hologram generation unit 67a generates a hologram (first calculation hologram) formed by two light waves having the Nth parameter from the multiple holograms I1, I2, …, I 2N-1 (first hologram generation step S26), and the second hologram generation unit 67b generates a hologram (second calculation hologram) formed by two light waves having the Nth parameter from the multiple hologram I 2N (second hologram generation step S27). Then, from the two generated holograms, the second light wave restoration unit 66b restores one light wave having the Nth parameter (second light wave restoration step S28). Thereafter, similar to the first embodiment, the amplitude and phase calculation unit 68 calculates the amplitude and phase at an arbitrary depth for each light wave (amplitude and phase calculation step S3), and the image reproduction unit 69 reproduces a three - dimensional image (image reproduction step). Hereinafter, each step will be described in detail.

[0056] As described above, for light waves in the blue wavelength band, the phase shift amounts α 31 (=-4π), α 32 (=-2π), α 33 (=0), α 34 (=2π), α 35 (=4π), α 36 are set in each of the multiple holograms I1, I2, …, I6, and this information is given from the spatial light phase modulator control unit 51 to the image reproduction device 6A. On the other hand, for each light wave in the red wavelength band and the green wavelength band, the phase shift amounts α i1 , α i2 , α i3 (=0), α i4 , α i5 , α i6This information is set and similarly provided to the image reconstruction device 6A. This allows the light waves in the green and red wavelength bands, excluding the blue wavelength band which is the Nth parameter, to be reconstructed from the multiple holograms I1, I2, ..., I5 using known methods (first light wave reconstruction step S25). An example is described below.

[0057] If we represent the hologram of only blue light wave interference fringes as I'3(x,y), then each of the multiple holograms I1, I2, ..., I5 can be expressed as shown in equations (17) to (21) below.

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[0058] Equations (17) to (21) yield equations (22) to (25).

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[0059] From the two simultaneous equations (=N-1) in equations (22) and (23), we find the (N-1)th parameter, i.e., the real part A2(x,y)cosφ2(x,y) of the green light wave, and from the two simultaneous equations (24) and (25), we find the imaginary part A2(x,y)sinφ2(x,y) of the green light wave. From the obtained real part A2(x,y)cosφ2(x,y) and imaginary part A2(x,y)sinφ2(x,y), we obtain A2(x,y) and cosφ2(x,y) for the green light wave. Similarly, we find the first parameter, i.e., the real part A1(x,y)cosφ1(x,y) and imaginary part A1(x,y)sinφ1(x,y) of the red light wave, and obtain A1(x,y) and cosφ1(x,y) for the red light wave.

[0060] Using the restored red and green wavelength bands of light, a multiple hologram I represented by equation (2) below is formed. j From any one of the (x,y)(j=1,2,…,2N-1) images, A for these light waves i (x,y), cosφ iThe term containing (x,y) is removed to generate a hologram I'1(x,y) consisting only of the interference fringes of the blue light wave, represented by equation (26) below (first hologram generation step S26). Similarly, from the multiple hologram I6, using the restored red and green wavelength bands of light waves, a hologram I'2(x,y) consisting only of the interference fringes of the blue light wave, represented by equation (27) below, is generated (second hologram generation step S27). Note that the first hologram generation step S26 and the second hologram generation step S27 may be performed in either order or in parallel.

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[0061] Equations (26) and (27), and the trigonometric formula (cosφ) 2 +(sinφ) 2 =1, therefore A3(x,y) 2 A two-dimensional equation is obtained. Here, α N2N (=α 36 By setting ) = π / 2, equations (26) and (27) can be simplified to equations (28) and (29) below. Substituting these into the trigonometric formulas yields equation (30), which can then be rearranged to obtain equation (31).

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[0062] As shown in equation (31), in order to solve the zero-order diffraction light intensity distribution, A3(x,y) 2 We set up a two-dimensional equation. Using the quadratic formula, we obtain equations (32) to (35) below.

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[0063] Equation (32) has two solutions, so we need to determine which one it is. Here, to simplify the equation, we consider the case where M=1. Substituting M=1 into equation (32), we get equation (36) below. The two A3(x,y) obtained from equation (36) are2 Substituting into equations (28) and (29) and rearranging, we obtain equations (37) and (38) below. Then, using the trigonometric formulas, we should obtain equation (39) below. However, the two A3(x,y) obtained in equation (36) 2 Not both of these satisfy equation (39). Specifically, with M3=1, for 0≦φ3(x,y)<2π, if the value of φ3(x,y) is 0≦φ3(x,y)≦π or 3π / 2≦φ3(x,y)<2π, then equation (39) is satisfied if the plus / minus sign (±) on the right side of equation (32) is negative (-), and if π<φ3(x,y)<3π / 2, then equation (39) is satisfied if the plus / minus sign (±) on the right side of equation (32) is positive (+). Since φ3(x,y) is an unknown variable, discrimination is necessary. One way to discriminate is to use equation (39) to determine which A3(x,y) should be adopted. 2 This is used as a verification formula to determine the value. A3(x,y) such that the left side of equation (39) is close to 1. 2 By employing this method, the zeroth order diffracted light intensity distribution can be determined, and the zeroth order diffracted light intensity distribution is subtracted from I'1(x,y) and I'2(x,y). Then, the A of the light wave of the Nth parameter is determined. N (x,y), φ N Information about (x,y) can be obtained. From the above, A3(x,y) and φ3(x,y) of the blue wavelength band light wave can be extracted (second light wave reconstruction step S28).

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[0064] Through the above processing, light waves in all wavelength bands can be restored, and thereafter, the amplitude / phase calculation step S3 and the image reproduction step S4 are performed in the same manner as in the first embodiment.

[0065] According to the image reconstruction method of this embodiment, similar to the modification of the first embodiment, an image containing light with a number of parameters N can be reconstructed from 2N multiple holograms, and the light waves of each parameter when recording the multiple holograms can be set to an arbitrary phase shift amount. Furthermore, since iterative calculations seen in the compression sensing algorithm for each parameter are unnecessary, the calculation time can be reduced and the image can be reconstructed at high speed. In addition, it can be applied even when the intensity ratio is 1 (1:1) or close to it, so clear interference fringes can be recorded. And, without approximation, A for each pixel N (x,y) 2 Since we are looking for A N (x,y) 2 This can also be solved under the condition that the elements are spatially distributed.

[0066] Multiple multiple holograms used in the image reproduction method by the image reproduction devices 6 and 6A according to the above embodiment can also be recorded in a spatially divided manner. For example, in order to obtain six multiple holograms for reproducing an image containing light in three wavelength bands, the spatial light phase modulator 1 simultaneously provides six different phase modulation patterns. To this end, the spatial light phase modulator 1 is equipped with six sets of cells 1a and 1b with different phase shift amounts α and α' for each multiple hologram. In other words, the spatial light phase modulator 1 is equipped with 12 types of cells with different phase shift amounts arranged in a mosaic pattern. Six patterns of interference fringes are formed with the light waves generated by such a spatial light phase modulator 1. The image sensor 2 then records these interference fringes as one multiple hologram in a single multiple recording. The image reproduction devices 6 and 6A extract one pixel each from each of the six-pixel sets of the image sensor 2 from this multiple hologram to prepare six multiple holograms.

[0067] (Modified example: Digital holography device) The spatial light phase modulator 1 of the hologram recording device of the digital holography apparatus 10, which performs the image reproduction method by the image reproduction devices 6 and 6A according to the above embodiment, can also be a reflective liquid crystal spatial light modulator. Hereinafter, a digital holography apparatus according to a modified embodiment of the present invention will be described with reference to Figure 7.

[0068] A digital holography apparatus 10A according to a first modified embodiment of the present invention includes a spatial light phase modulator 1A (light wave generation means) composed of a first spatial light phase modulator 11A and a second spatial light phase modulator 12A, instead of the spatial light phase modulator 1, and further includes a 4f optical system 41 arranged between the first spatial light phase modulator 11A and the second spatial light phase modulator 12A. Otherwise, the configuration can be the same as that of the digital holography apparatus 10 according to the above embodiment.

[0069] The first spatial light phase modulator 11A and the second spatial light phase modulator 12A are reflective liquid crystal spatial light modulators such as LCOS (Liquid Crystal On Silicon)-SLM. In the digital holography apparatus 10A, the first spatial light phase modulator 11A receives light L incident from the object OBJ. OBJ Light L0, L 90 The light is reflected and transmitted through the 4f optical system 41 to the second spatial optical phase modulator 12A, and the second spatial optical phase modulator 12A receives the light L0,L from the first spatial optical phase modulator 11A. 90The optical phase modulators are arranged to reflect the light and cause it to enter the image sensor 2. The first spatial optical phase modulator 11A and the second spatial optical phase modulator 12A have the same configuration as the first spatial optical phase modulator 11 and the second spatial optical phase modulator 12 of the digital holography apparatus 10 according to the above embodiment, except for the difference between reflective and transmissive types. Therefore, the first spatial optical phase modulator 11A is equipped with the same number of optical phase modulation elements 11a and 11b, and the second spatial optical phase modulator 12A is equipped with the same number of optical phase modulation elements 12a and 12b, arranged at the same pitch, and the polarization directions of the light phase-modulated by the optical phase modulation elements 11a and 11b and the optical phase modulation elements 12a and 12b are orthogonal to each other (see Figure 2). Furthermore, the optical phase modulation elements 11a and 12a, and the optical phase modulation elements 11b and 12b have the same phase shift amount and are arranged at the same position when viewed in the optical axis direction. Here, light incident on a certain point on the incident plane of the 4f optical system 41 exits from a point on the exit plane that is rotated 180° with respect to the optical axis of the 4f optical system 41 as the origin. Taking this into consideration, the optical phase modulation elements 12a and 12b of the second spatial optical phase modulator 12A are arranged to match the arrangement of the optical phase modulation elements 11a and 11b of the first spatial optical phase modulator 11A.

[0070] Here, the optical phase modulation elements 11a and 11b of the first spatial optical phase modulator 11A phase modulate the light L0 with a polarization direction perpendicular to the plane of the paper in Figure 7, and the light L with a polarization direction perpendicular to it. 90 The optical phase modulation elements 12a and 12b of the second spatial optical phase modulator 12A perform phase modulation on the light L from the object OBJ. OBJ When it is incident on the first spatial optical phase modulator 11A and reflected, light L 90 While the first light is not modulated, the second light L0 forms six light waves, two for each wavelength band. And these lights L0, L 90 When the light enters the second spatial optical phase modulator 12A and is reflected, the six light waves L0 are not modulated, and light L 90This forms six light waves, two for each wavelength band. As described above, the optical phase modulation elements 11a and 12a (collectively referred to as cell 1a), and the optical phase modulation elements 11b and 12b (collectively referred to as cell 1b) have equal phase shift amounts, and the 4f optical system 41 is positioned between the first spatial optical phase modulator 11A and the second spatial optical phase modulator 12A, so that the light L0, L0 is reflected sequentially from the first and second spatial optical phase modulators 11A and 12A. 90 In this configuration, the phases are aligned for each cell 1a and 1b. With this configuration, the spatial optical phase modulator 1A, like the spatial optical phase modulator 1 of the above embodiment, can perform phase modulation for each of the two-dimensionally arranged cells without polarization dependence for light of all polarization directions.

[0071] The hologram recording device of the digital holography apparatus 10A according to this modified example can record multiple holograms, similar to the digital holography apparatus 10 according to the above embodiment. Furthermore, since the spatial optical phase modulator 1A (first and second spatial optical phase modulators 11A, 12A) is made of LCOS-SLM, it achieves high resolution and fast response, and regardless of whether the multiple holograms are divided and recorded temporally or spatially, a decrease in the resolution of the reproduced image can be suppressed.

[0072] As described above, the digital holography apparatus 10, 10A according to this embodiment and its modified form allows for arbitrary setting of the number of wavelength bands. Furthermore, a color filter array, in which color filters of different colors are arranged in a mosaic pattern, can be provided on the light incident surface side of the image sensor 2, further subdividing the wavelength bands of light transmitted through each color filter. In addition, the spatial optical phase modulators 1, 1A can be any medium that has wavelength dependence and generates different radii of curvature at the wavefront for each cell 1a, 1b. Such spatial optical phase modulators 1, 1A are not limited to liquid crystal spatial optical modulators, and non-birefringent, i.e., non-polarization dependent holographic optical elements or diffractive optical elements may be applied as optical phase modulators.

[0073] The digital holography apparatus 10, 10A according to this embodiment and its modified form can record a multiple hologram for reproducing an image that includes polarization direction as information by applying a liquid crystal spatial light modulator to a spatial light phase modulator, and can also reproduce an image from this multiple hologram. For this purpose, in the spatial light phase modulator 1(1A), the optical phase modulation elements 11a and 12a, and optical phase modulation elements 11b and 12b of the first and second spatial light phase modulators 11(11A) and 12(12A) are set to have different phase modulation amounts. With this configuration, x-polarization L0 and y-polarization L 90 These are formed as two independent light waves, and are recorded as multiplexed holograms by the image sensor 2 as different interference fringe patterns. In this case, the 4f optical system 41 between the first spatial light phase modulator 11A and the second spatial light phase modulator 12A is not required in the digital holography apparatus 10A. Furthermore, the polarization direction is not limited to two directions, and can be subdivided into three or more directions depending on the configuration of the spatial light phase modulator 1 (1A).

[0074] Such multiple holograms include information about the wavelength band, along with the polarization direction, similar to the embodiment described above. For example, if the wavelength band is represented by three parameters, R, G, and B, then, combined with the two polarization direction parameters in the x and y directions, an image containing a total of six parameters of light can be reconstructed. To achieve this, N=6, and 6 to 12 multiple holograms are recorded, divided temporally or spatially, depending on the image reconstruction method.

[0075] The digital holography apparatus 10, 10A according to this embodiment and its modified form can also divide the field of view of an object (subject) OBJ into multiple parameters as information. To this end, the hologram recording apparatus of the digital holography apparatus 10, 10A can be configured to apply a different phase modulation pattern to each divided field of view of the object OBJ and perform multiplex recording with the image sensor 2. Specifically, the hologram recording apparatus is equipped with the same number of spatial light phase modulators 1 (1A) as the number of divided fields of view, and the light L emitted from each field of view OBJThe optical system is provided to introduce different spatial optical phase modulators 1, and the interference fringes formed by the light waves generated by each spatial optical phase modulator 1 are multiplexed and recorded by the image sensor 2. Alternatively, the hologram recording device may be equipped with one spatial optical phase modulator 1 (1A), which is divided according to the division of the field of view, and a different phase modulation pattern may be given to each divided region.

[0076] The digital holography apparatus 10, 10A according to this embodiment and its modified form are equipped with a wavelength-dependent spatial light phase modulator, such as a liquid crystal spatial light modulator, which allows for the reproduction of images containing information for each wavelength band, as described above. Furthermore, by converting wavelength information into time, it is possible to reproduce three-dimensional images for multiple time points (times) from a multiple hologram captured in a single image as a video exceeding the response time (temporal resolution) of the image sensor 2. Hereinafter, a digital holography apparatus according to another modified form of the embodiment of the present invention, as well as a hologram recording method and an image reproduction method using this digital holography apparatus, will be described with reference to Figure 8.

[0077] A digital holography apparatus 10B according to a second modification of an embodiment of the present invention comprises a multi-wavelength light source 3, a wavelength-dispersing element 42, polarizing beam splitters (PBS) 43a, 43b, mirrors 44a, 44b, an optical phase modulation element array 1B, a polarizer 47a, an image sensor 2, and a computer 50. The multi-wavelength light source 3 and the wavelength-dispersing element 42 are optical systems that emit pulsed light with different timings for each wavelength. To convert each wavelength component into time information, the multi-wavelength light source 3 can be an optical comb light source or a wide-wavelength pulse light source. The wavelength-dispersing element 42 is an optical element having a wavelength-dependent refractive index such as a prism, a diffraction grating, or a combination thereof. The polarizer 47a and the optical phase modulation element array 1B are stacked on the imaging surface of the image sensor 2. The optical phase modulation element array 1B, like the first and second spatial optical phase modulators 11 and 12 of the spatial optical phase modulator 1 shown in Figure 2, is composed of a two-dimensional arrangement of optical phase modulation elements having polarization dependence and wavelength dependence, but the phase shift amount of each optical phase modulation element does not need to be variable. Such an optical phase modulation element array 1B is composed of a two-dimensional arrangement of birefringent optical elements made of photonic crystals, liquid crystal materials, metamaterials, or minute waveplates (see Patent Documents 1 and 2), and phase modulates unidirectional polarization, in this case the transverse polarization in Figure 8, according to the wavelength. Furthermore, in this modified example, in order to record multiple multiple holograms by spatially dividing them, the optical phase modulation element array 1B is provided with cells (optical phase modulation elements) arranged to give a phase modulation pattern for the number of multiple holograms to be recorded. The polarizer 47a is positioned on a transmission axis tilted at 45° with respect to the mutually orthogonal p-polarization and s-polarization separated by the polarization beam splitter 43a.

[0078] The pulsed light emitted from the multi-wavelength light source 3 becomes light L with different pulse timings for each wavelength via the wavelength-dispersing element 42. This light L is then separated by the polarization beam splitter 43a into p-polarized light that is transmitted and travels in a straight line and s-polarized light that is reflected. The s-polarized light with a polarization direction perpendicular to the plane of the paper in Figure 8 is the object light L. OBJ The object (subject) OBJ is illuminated. At this time, the object light L OBJThe timing of illuminating the object OBJ differs for each wavelength. On the other hand, the p-polarized light transmitted through the polarizing beam splitter 43a is the reference light L Ref As such, object light L OBJ It travels along a different optical path. And object light L OBJ and reference light L Ref The light is combined by the polarization beam splitter 43b and incident on the optical phase modulation element array 1B. The optical phase modulation element array 1B receives the reference light L, which is polarized in the transverse direction as shown in Figure 8. Ref The polarizer 47a modulates the light L, which has the same polarization direction. OBJ ,L Ref This forms interference fringes for each wavelength, which are then recorded as a multiplex hologram by the image sensor 2.

[0079] The modified digital holography apparatus 10B obtains a predetermined number of multiple holograms by extracting one pixel at a time from a set of a predetermined number of pixels of the image sensor 2, as described above, from a single multiple hologram recorded in one imaging by the image sensor 2. From these multiple holograms, the light waves for each wavelength are reconstructed by the image reconstruction method according to the first or second embodiment described above. Since the reconstructed image for each wavelength contains three-dimensional information of the object OBJ at different times, a three-dimensional moving image can be obtained in a single exposure (measurement). By applying the modified image reconstruction apparatus, the spatial density of the optical phase modulation element array 1B can be increased, and a high-quality image can be reconstructed. Furthermore, by applying the image reconstruction apparatus, more wavelength (time) information can be recorded at the same spatial density compared to when the optical phase modulation element array 1B is designed with a conventional image reconstruction apparatus, thus extending the time of moving image recording. Note that in Figure 8, the object OBJ is shown as transmitting light, but it may also be reflective. Furthermore, the wavelength-dispersing element 42 may be placed on the optical path between the polarizing beam splitter 43a and the object OBJ, and on the optical path between the polarizing beam splitters 43a and 43b, respectively. In addition, the digital holography apparatus 10B according to this modified example may also include the first spatial optical phase modulator 11 of the spatial optical phase modulator 1 instead of the optical phase modulation element array 1B.

[0080] A hologram recording method and image reproduction method using a digital holography apparatus 10, 10A according to embodiments and modifications thereof of the present invention (hereinafter referred to as the hologram recording method and image reproduction method according to the present invention) can also be performed by applying a known optical microscope to the hologram recording apparatus. As an example, an embodiment in which a fluorescence microscope is applied will be described with reference to Figure 9. The digital holography apparatus 10C shown in Figure 9 comprises an excitation light source 3A, a dichroic mirror 45, magnification optical systems (lenses) 41a, 41b, an eyepiece lens 41c, an excitation light shielding element 46, a mirror 44, polarizers 47a, 47b, birefringent materials 48a, 48b, 48c, a spatial light phase modulator 11A, an image sensor 2, and a computer 50. With this configuration, a multiple hologram can be recorded in which an image of a fluorescent sample can be reproduced as an object OBJ, and an image can be reproduced from the multiple hologram.

[0081] The excitation light source 3A irradiates light (excitation light) that simultaneously excites multiple phosphors with different emission colors. The spatial light phase modulator 11A is the first spatial light phase modulator 11A of the spatial light phase modulator 1A shown in Figure 7, and it phase-modulates unidirectional polarization, in this case the 0° direction or 90° direction described later, according to the wavelength. The dichroic mirror 45 reflects the excitation light irradiated from the excitation light source 3A and transmits the fluorescence emitted from the fluorescent sample OBJ. The excitation light shielding element 46 shields the excitation light and transmits the fluorescence. The dichroic mirror 45 and the excitation light shielding element 46 are optical elements provided to separate the excitation light and fluorescence, and both do not transmit the excitation light and transmit the fluorescence. For this reason, it is preferable that the dichroic mirror 45 and the excitation light shielding element 46 are set to transmit wavelengths across the entire fluorescence wavelength spectrum to avoid attenuation of fluorescence. Specifically, for example, a long-pass filter that transmits light with wavelengths of 510 nm or more can be set for fluorescence that emits light in the 510-700 nm wavelength range. As a result, the shape of the fluorescence wavelength spectrum is not disturbed by the dichroic mirror 45 or the excitation light shielding element 46, and the fluorescence can be imaged brightly. The polarizers 47a and 47b are positioned with their transmission axes at 45° and 135°, respectively.

[0082] The excitation light emitted from the excitation light source 3A is reflected by the dichroic mirror 45 and passes through the magnifying optical system 41a from the eyepiece lens 41c side, thus illuminating the fluorescent sample OBJ with a reduced beam diameter. The fluorescent sample OBJ emits fluorescence of multiple different wavelength spectra. This fluorescence sequentially passes through the eyepiece lens 41c, the magnifying optical system 41a, the dichroic mirror 45, and the excitation light shielding element 46, and is reflected by the mirror 44. In addition, some of the excitation light, along with the fluorescence, passes through the eyepiece lens 41c from the fluorescent sample OBJ side, but is separated from the fluorescence by the dichroic mirror 45 and the excitation light shielding element 46. The fluorescence reflected by the mirror 44 is transmitted by the polarizer 47a as linearly polarized light at a 45° angle. The fluorescence, polarized at 45°, has its phase difference adjusted by the birefringent material 48a to increase the visibility of the resulting interference fringes. The phase difference between the 0° and 90° polarized components is then adjusted, and the light passes through lens 41b before being incident on a reflective spatial light phase modulator 11A. The spatial light phase modulator 11A then applies a phase modulation amount corresponding to the wavelength to either the 0° or 90° polarized component. The light emitted from the spatial light phase modulator 11A is then subjected to the birefringent material 48b, which applies different wavefront modulations to the 0° and 90° polarized components. Specifically, a phase distribution of spherical waves with different radii of curvature is applied depending on the polarization direction. As a result, light waves polarized at 0° and 90° with different radii of curvature are generated. Next, the birefringent material 48c adjusts the difference in optical path lengths between the polarization in the 0° direction and the polarization in the 90° direction, as well as the difference in the radius of curvature of the two light waves, in order to increase the visibility of the interference fringes obtained in the final product. Then, the polarizer 47b in the direction of the transmission axis 45° aligns the polarization directions of the two light waves, and interference fringes for each wavelength are generated. The image sensor 2 records these interference fringes as multiple holograms. At this time, as described in the above embodiment, the spatial optical phase modulator 11A applies a different phase modulation amount to at least one light wave in one wavelength band, and the image sensor 2 records multiple multiple holograms while changing the phase modulation amount.

[0083] By applying the hologram recording method and image reproduction method according to the present invention to a fluorescence microscope, multiple holograms necessary for image reproduction can be obtained with less light and fewer measurements, enabling high-speed measurements with weak light. Therefore, damage to the subject can be reduced, especially when the subject is a living organism. Furthermore, when an image sensor equipped with an optical phase modulation element array and a polarizer is applied, the spatial density of the optical phase modulation element array can be increased, resulting in higher-quality images. When recording multiple multiple holograms by spatially dividing the area, an optical phase modulation element array 1B stacked on the imaging surface of the image sensor 2 together with a polarizer 47b can be applied instead of the spatial optical phase modulator 11A (see Figure 8). Since the spatial density of the optical phase modulation element array 1B can be increased, high-quality images can be reproduced.

[0084] As another example, a manner in which a quantitative phase microscope is applied will be described with reference to Figure 10. The digital holography apparatus 10D shown in Figure 10 comprises an incoherent light source 3B such as an LED, a collimator (lens) 41d, a spatial light phase modulator 11, polarizers 47a, 47b, and 47c, a birefringent material 48d, a glass cell 49 for housing a sample (object OBJ), an image sensor 2, and a computer 50. The glass cell 49 and the spatial light phase modulator 11 are arranged side by side on a plane perpendicular to the optical axis. Furthermore, polarizer 47a is positioned directly below the glass cell 49, and polarizer 47b is positioned directly below the spatial light phase modulator 11. The birefringent material 48d is positioned below the side by side polarizers 47a and 47b. Below the birefringent material 48d, the glass cell 49 is positioned, polarizer 47c is positioned directly below polarizer 47a, and the image sensor 2 is positioned further below that. The spatial optical phase modulator 11 is the first spatial optical phase modulator 11 of the spatial optical phase modulator 1 shown in Figure 2, and it phase modulates unidirectional polarization, in this case polarization in the direction of the transmission axis of polarizer 47b (transverse polarization in Figure 10), according to the wavelength. The transmission axes of polarizers 47a and 47b are orthogonal to each other, and the transmission axis of polarizer 47c is tilted at 45° relative to polarizers 47a and 47b. Note that the spatial optical phase modulator 11 and polarizer 47b may be swapped. The birefringent material 48d is made of calcite (CaCO3), etc., and its optical axis is oriented so as to refract linearly polarized light transmitted through polarizer 47b. The glass cell 49 is rotatable in three axial directions.

[0085] Light L, emitted from the incoherent light source 3B and becoming parallel light after passing through the collimator 41d, partially passes through the glass cell 49 and enters the object OBJ, while another portion enters the spatial light phase modulator 1. Light L (object light) emitted from the object OBJ. OBJ The light passes through polarizer 47a and emits linearly polarized light in the direction perpendicular to the plane of the paper as shown in Figure 10. The linearly polarized light L OBJ The light travels in a straight line through the birefringent material 48d and is incident on the polarizer 47c on the image sensor 2. Meanwhile, the light (reference light) L that has passed through the spatial light phase modulator 11 and the polarizer 47b Ref is, Light L OBJThe light becomes linearly polarized in a direction perpendicular to the direction of the optical phase modulator 11, and is generated into a number of light waves equal to the number of multiple holograms recorded for each wavelength band, resulting in spherical waves with different radii of curvature. The linearly polarized light L Ref The light L is refracted and transmitted through the birefringent material 48d and incident on the polarizer 47c on the image sensor 2. Then, the light L has the same polarization direction as the polarizer 47c. OBJ ,L Ref These create interference fringes for each wavelength band and are recorded as a multiplex hologram by the image sensor 2.

[0086] By applying the hologram recording method and image reconstruction method according to the present invention to a quantitative phase microscope, multiple holograms necessary for image reconstruction can be obtained with less light and fewer measurements, enabling measurements at low light and high speed. Therefore, damage to the subject can be reduced, especially when the subject is a living organism. Furthermore, since three-dimensional imaging is possible from quantitative phase information even with transparent samples, staining of the sample can be eliminated. In addition, by recording multiple holograms while rotating in three axes using a glass cell 49, three-dimensional tomographic images of transparent samples can be obtained without staining.

[0087] The above describes various embodiments for implementing the image reproduction apparatus, hologram recording apparatus, and digital holography apparatus according to the present invention. However, the present invention is not limited to these embodiments, and various modifications are possible within the scope of the claims. [Examples]

[0088] To confirm the effects of the present invention, a simulation of hologram recording and image reproduction using a digital holography apparatus according to a modified embodiment of the present invention shown in Figure 7 was performed using Microsoft Visual Studio 2017. As objects (subjects), three spherical light emitters with a diameter of 64 μm, colored red (R), green (G), and blue (B), were set as the objects (subjects), as shown in Figure 11. The red light emitter had a central wavelength of 618 nm, the green light emitter had a central wavelength of 545 nm, and the blue light emitter had a central wavelength of 461 nm. Each had a rectangular wavelength spectrum, with a wavelength width of ±5 nm from the central wavelength (total of 10 nm). In the calculation, the wavelength spacing was 0.1 nm, and therefore each light emitter was calculated as a hologram of 101 wavelengths in a single wavelength band.

[0089] The image sensor consisted of a 512×512 pixel array with a pixel size of 4μm. The first and second spatial light modulators each consisted of a 512×512 pixel array with a pixel size of 4μm, and the cells for generating the two light waves were set using a pseudo-random function. The splitting ratio (intensity ratio) of the two light waves was set to 1:1. Furthermore, a non-aliased spherical wave phase distribution was given to the generation region of one of the two light waves, and a relative phase shift amount to the other generation region was given to the value described later.

[0090] The distance between the object and the first spatial light modulator was adjusted so that the diffracted light from the object spread to the first and second spatial light modulators, and the distance between the second spatial light modulator and the image sensor was adjusted so that the interference light of the two light waves spread to the image sensor. Multiple holograms of interference fringes in three wavelength bands were imaged six times while varying the amount of phase shift. The amount of phase shift in each multiple hologram was set to the following values ​​for wavelengths of 618 nm, 545 nm, and 461 nm, respectively. 1: [-(434 / 360)×2π,-3π,-4π] 2: [-(217 / 360)×2π,-3π / 2,-2π] 3: [0,0,0] 4: [(217 / 360)×π / 2,3π / 8,π / 2] 5:〔(217 / 360)×2π,3π / 2,2π〕 6:〔(434 / 360)×2π,3π,4π〕

[0091] Figure 12 shows six multiplex holograms when the distance between the object and the first spatial light modulator is 50 mm, the distance between the second spatial light modulator and the image sensor is 20 mm, and the focal length of the spherical waves generated by the first and second spatial light modulators is set to 50 mm. Furthermore, using the image reconstruction method according to the second embodiment of the present invention (see Figure 6), the image is first reconstructed by reconstructing the light waves for each wavelength band of green and blue, and then the image is reconstructed by reconstructing the light waves for the red wavelength band, and the resulting color-combined image is shown in Figure 13. The reconstructed image was obtained by rotating the image 180° around the origin at the center of the image using the birefringent lens pattern displayed by the spatial light modulator.

[0092] Furthermore, Figure 14 shows six multiplex holograms when the distance between the object and the first spatial light modulator is 25 mm, the distance between the second spatial light modulator and the image sensor is 5 mm, and the focal length of the spherical waves generated by the first and second spatial light modulators is 340 mm. Figure 15 shows the image obtained by reconstructing images for each wavelength band from these six multiplex holograms using the same image reconstruction method as described above, and then color-compositing them. Since the images and wavelength information of the three objects shown in Figure 11 were successfully reconstructed under both conditions, the validity of the principle of the image reconstruction method using the image reconstruction device according to the present invention was confirmed. It was also confirmed that shortening the focal length of the spherical waves generated by the spatial light modulator improves the resolution of the digital holography device. [Examples]

[0093] To confirm the effects of the present invention, hologram recording and image reproduction were performed using a digital holography apparatus equipped with a fluorescence microscope as shown in Figure 9. Two types of fluorescent samples, europium complex and terbium complex, with emission center wavelengths of 618 nm and 545 nm, respectively, were prepared as subjects (objects). These fluorescent samples had a diameter of approximately 10 μm. Four multiplexed fluorescence holograms, as shown in Figure 16, were recorded while applying phase modulation amounts of (-210π / 127,-2π), (-105π / 254,-π / 2), (0,0), and (210π / 127,2π) for each center wavelength.

[0094] From the four recorded multiple holograms, the image was first reconstructed by reconstructing the green (center wavelength 545 nm) light wave using the image reconstruction method according to the second embodiment of the present invention (see Figure 6), and then the image was reconstructed by reconstructing the red (center wavelength 618 nm) light wave. The images of each wavelength on the imaging surface are shown in Figure 17A. The color-combined image is shown in Figure 18A. Furthermore, the light waves at a depth of 75 μm relative to the imaging surface were calculated from the reconstructed light waves of each color using diffraction integration, and the reconstructed images of each wavelength are shown in Figure 17B, and the color-combined image is shown in Figure 18B. Similarly, the images of each wavelength at a depth of 106 μm relative to the imaging surface were reconstructed and shown in Figure 17C, and the color-combined image is shown in Figure 18C. Thus, it was confirmed that the image reproduction method using the image reproduction device according to the present invention allows for the reduction of the number of measurements for two types of phosphors to four (twice the number of parameters) in color multiplex incoherent digital holography using a computational coherent multiplexing method, enabling identification by fluorescence color, and furthermore, enabling measurement of a sample with a diameter of approximately 10 μm over a depth of 100 μm. [Explanation of Symbols]

[0095] 10, 10A, 10B, 10C, 10D Digital Holography System 1.1A Spatial optical phase modulator (optical wave generation means) 2 Image sensors 11,11A First spatial optical phase modulator (first spatial optical phase modulation section) 11a, 11b Optical phase modulation element 12,12A Second spatial optical phase modulator (second spatial optical phase modulation section) 12a, 12b Optical phase modulation element 2 Image sensors 3 Multi-wavelength light source 3A Excitation light source 3B Incoherent Light Source 41 4f optical system 41a, 41b lenses 42 wavelength dispersive elements 43a, 43b Polarizing Beam Splitter 45 Dichroic Mirror 46 Excitation light shielding element 47a,47b,47c polarizer 48a, 48b, 48c, 48d Birefringent materials 50 Computer (PC) 5. Recording Control Unit 51 Spatial Optical Phase Modulator Control Unit 52 Image sensor control unit 6,6A Image reproduction device 61 Multiple Hologram Acquisition Unit 62 Storage section 63 Parameter Selection Section 64 Hologram generation unit 65. Lightwave Restoration Unit 66a First Optical Wave Restoration Unit 66b Second Optical Wave Restoration Unit 67a First Hologram Generation Unit 67b Second Hologram Generation Unit 68 Amplitude / phase calculation section 69 Image Playback Unit S1, S1A Multiple Hologram Acquisition Step S21 Parameter selection step S22 Hologram generation step S23 Lightwave Restoration Step S25 First Lightwave Restoration Step S26 First Hologram Generation Step S27 Second Hologram Generation Step S28 Second Lightwave Restoration Step S3 Amplitude and Phase Calculation Step S4 Image Playback Step

Claims

1. An image reproduction device that reproduces an image containing N different types of light, each containing N different types of light waves, each containing N different types of light waves, each containing one interference fringe formed by two light waves with different phases for each of the N parameters, and recorded in a temporally or spatially divided manner, wherein at least one of the 2N types of light waves that formed the N patterns of interference fringes has a phase that is different from the others. A parameter selection unit that selects one parameter at a time N times from the aforementioned N parameters, When the parameter selection unit selects parameters, the hologram generation unit removes interference fringes of (N-1) patterns other than those formed by the two light waves having the selected parameters from at least one of the multiple holograms, and generates a computational hologram including the two light waves. The system includes a light wave reconstruction unit that reconstructs one of the two light waves from the computational hologram generated by the hologram generation unit, The image reproduction apparatus is characterized in that, after the optical wave reconstruction unit has reconstructed one or more optical waves, the optical wave reconstruction unit uses at least one of the optical waves reconstructed by the optical wave reconstruction unit and the computational hologram used to reconstruct the optical waves in order to generate a computational hologram that includes two optical waves having different parameters from the reconstructed optical waves.

2. An image reproduction device that reproduces an image containing N different types of light, each containing one or more parameters or combinations of parameters for one or more optical information such as wavelength band, polarization direction, and measurement areas divided into multiple sections of the field of view, from 2N multiplexed holograms recorded by multiplexing and dividing them temporally or spatially, with each parameter containing one interference fringe formed by two light waves with different phases, for a total of N patterns, wherein the interference fringes are recorded one by one for each parameter, and the holograms are recorded by multiplexing and dividing them temporally or spatially. A first light wave reconstruction unit reconstructs (N-1) types of light waves, one of two light waves that formed interference fringes other than the Nth interference fringe, from (2N-1) multiple holograms, excluding the second N multiple hologram, which has a different phase for at least one of the 2N types of light waves that formed the N patterns of interference fringes, and each of the (N-1) types of light waves that have a different phase for at least one of the 2N types of light waves, among the 2N multiple holograms mentioned above. A first hologram generation unit generates a first calculated hologram by using the light waves restored by the first light wave reconstruction unit to remove interference fringes of (N-1) patterns other than the interference fringes of N from at least one of the multiple holograms other than the second N multiple hologram, A second hologram generation unit generates a second computational hologram by using the light waves reconstructed by the first light wave reconstruction unit to remove interference fringes of (N-1) patterns other than the interference fringes of N from the second N multiple hologram, An image reproduction apparatus comprising: a second optical wave reconstruction unit that reconstructs one of the two optical waves that formed the interference fringes N from the first computational hologram and the second computational hologram by a phase shift method.

3. A hologram recording apparatus comprising: a light wave generation means that generates N light waves with different wavelength parameters, each pulsed with different timings and phases, and an image sensor that receives the light waves generated by the light wave generation means and multiple-records interference fringes formed by two light waves with the same parameters but different phases as multiple holograms in two or more different parameter patterns, wherein the two or more interference fringes are spatially divided and recorded to record a single multiple hologram, The light wave generating means generates one of the two light waves from the light wave of the object, The hologram recording device is characterized in that the light waves have a different phase for at least one of the light waves that form the two or more interference fringes recorded in each of the predetermined number of multiple holograms, which are obtained by extracting one pixel from each set of a predetermined number of pixels of the image sensor from the single multiple hologram.

4. A hologram recording apparatus comprising: an optical wave generation means that generates N types of optical waves with different phases for each of the following parameters from the optical wave of an object: wavelength band, polarization direction, and measurement area divided into multiple sections; an image sensor that receives the optical waves generated by the optical wave generation means and multiple-records interference fringes formed by two optical waves with the same parameters but different phases as multiple holograms, wherein the two or more patterns of interference fringes are recorded in a temporally or spatially divided manner, thereby recording multiple multiple holograms; The light wave generation means comprises a first spatial optical phase modulation unit and a second spatial optical phase modulation unit, which are arranged in a two-dimensional array of optical phase modulation elements, wherein the optical phase modulation elements of the first spatial optical phase modulation unit and the second spatial optical phase modulation unit modulate the phase of light with respect to light with different polarization directions. The hologram recording device is characterized in that the light waves have a different phase with respect to at least one of the light waves that form the two or more interference fringes recorded in each of the multiple holograms.

5. The hologram recording apparatus according to claim 4, characterized in that the first spatial optical phase modulation unit and the second spatial optical phase modulation unit have the same amount of phase modulation by the optical phase modulation elements arranged at the same position in the optical axis direction.

6. A hologram recording apparatus comprising: a light wave generation means that generates two or more light waves with different phases for each of the N parameters of the wavelength band; and an image sensor that receives the light waves generated by the light wave generation means and multiple-records interference fringes formed by two light waves with the same parameters but different phases as multiple holograms in two or more different parameter patterns, wherein the two or more interference fringes are recorded in a temporally or spatially divided manner, thereby recording multiple multiple holograms, The light wave generation means comprises a spatial light phase modulation unit formed by a two-dimensional arrangement of light phase modulation elements, and a birefringent material arranged such that the light wave emitted from the spatial light phase modulation unit and the light wave from the object are incident on different regions of the incident surface, wherein one of the light wave emitted from the spatial light phase modulation unit and the light wave from the object travels straight through the birefringent material, and the other is refracted and incident on the image sensor. The hologram recording device is characterized in that the light waves have a different phase with respect to at least one of the light waves that form the two or more interference fringes recorded in each of the multiple holograms.

7. An image reproduction apparatus according to claim 1 or claim 2, and A digital holography apparatus comprising: a light wave generation means that generates N different light waves for each of the following parameters from the light wave of an object, with different phases for each parameter, and each of the parameters or combinations thereof for one or more optical information such as wavelength band, polarization direction, and measurement area divided into multiple sections of the field of view; and an image sensor that receives the light waves generated by the light wave generation means and multiple-records interference fringes formed by two light waves with the same parameters but different phases as multiple holograms in two or more different parameter patterns, wherein the two or more interference fringes are recorded in a temporally or spatially divided manner, thereby recording multiple multiple holograms, A digital holography apparatus in which, for each of the multiple multiple holograms, the light waves have a phase difference with respect to at least one of the light waves that form the two or more interference fringes recorded in each multiple hologram.

Images