Object shape measuring device and object shape measuring method

Abstract

To solve the problem in which: in a prior art, a technique using a hologram recording medium, for example, requires preparation such as preliminary experiment for determining the threshold of light intensity obtained by an optical detector and has a drawback in that the phase and amplitude distributions of a target object cannot easily be obtained from acquisition of correction by light intensity, and another technique, such as an SPI, also has a drawback in that encoded light needs to be acquired a number of times in order to reconstruct the target object.SOLUTION: Provided is an object shape measurement device 1 which is based on the application of an SPI that realizes high accuracy and fast imaging by constituting the SPI using a hologram recording medium 6 in which a plurality of phase modulation patterns, with multiple stages of phase shift applied, are recorded as hologram that are generated using a two-dimensional spatial light modulator that modulates the amplitude and / or phase of light by a plurality of pixels in advance, and a spatial filter 8 having an aperture which is about the size of one pixel of the two-dimensional spatial light modulator.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to single pixel imaging that realizes high-precision, high-resolution, and high-speed imaging, and to an object shape measuring device that realizes object shape measurement and imaging using an image processing method. [Background technology]

[0002] A technique using a holographic recording medium has been proposed as an imaging technology for target objects. It is known that a complex amplitude distribution, including the amplitude and phase distributions of the object light, can be recorded by irradiating a recording medium, such as a holographic recording medium, with the interference of an object light and a reference light as interference light. Because the phase distribution reflects information dependent on the refractive index of the object, recording media capable of recording complex amplitude distributions have the advantage of being able to directly record shape information of the object. In this regard, there is a device for detecting the phase distribution of a target object (see Patent Document 1). This device determines whether or not there is a correlation with the target object based on whether the light intensity emitted from the holographic recording medium and detected by a photodetector exceeds a threshold value. However, determining the threshold value requires prior preparation, such as experiments, and it is difficult to obtain detailed information about the phase and amplitude distributions of the target object simply by obtaining correlations based on light intensity.

[0003] Another technology is single-pixel imaging (SPI), hereafter referred to as SPI. This is a method of imaging a target object using a single-pixel photodetector with a single-pixel light receiving section. In this method, an optical system applies pattern information to the target object to encode the target object, and the encoded light is acquired by a single-pixel photodetector, and a reconstruction calculation is performed on a computer to obtain an image of the target object. This method is described in Patent Document 2, and the acquisition of complex amplitude images is described in Non-Patent Document 1. However, SPI has the problem of taking a long time to reconstruct the image because the encoded light must be acquired multiple times. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2009-237085 [Patent Document 2] Patent Publication No. 2021-100186 [Non-patent literature]

[0005] [Non-Patent Document 1] L. Martinez-Leon, P. Clemente, Y. Mori, V. Climent, J. Lancis, and E. Tajahuerce, “Single-pixel digital holography with phase-encoded illumination,” Opt. Express 25(5), 4975-4984 (2017). Summary of the Invention [Problem to be solved by the invention]

[0006] In conventional technologies, for example, methods using holographic recording media have had issues such as the need for prior experimental preparation to determine the threshold value of the light intensity obtained by the photodetector, and the difficulty of obtaining detailed phase and amplitude distributions of the target object from correlations obtained using light intensity.

[0007] Another method is SPI, which acquires an image of the target object by capturing encoded light from the target object using a single-pixel photodetector and performing reconstruction calculations on a computer.However, this method has the drawback of taking a long time to reconstruct the image because the encoded light must be captured multiple times. [Means for solving the problem]

[0008] As a means of solving the above problem, an object shape measurement device that applies SPI to achieve high-precision, high-speed imaging can be created by configuring an SPI using a hologram recording medium on which interference fringes generated in advance using a two-dimensional spatial light modulator that modulates the amplitude and / or phase of light using multiple pixels are recorded as a hologram, and a spatial filter with an aperture approximately the size of one pixel of the two-dimensional spatial light modulator. [Effects of the Invention]

[0009] According to the present invention, by acquiring the optical correlation intensity of one pixel, it is possible to acquire a complex amplitude image of the target object or diffracted from the target object, thereby providing three-dimensional information of the target object and quantitative phase information such as refractive index and thickness. Furthermore, by applying an optical correlator to the above-mentioned holographic recording medium, it is possible to acquire the correlation between the phase modulation pattern and the target object at high speed, thereby enabling the provision of a high-speed reconstructed image of the target object. Furthermore, unlike conventional two-dimensional imaging devices, the spatial resolution depends on the phase modulation pattern, so that by increasing the number of pixels per unit length of the phase modulation pattern used, it is possible to provide a highly accurate reconstructed image.

[0010] For these reasons, there is a high possibility that this technology will be applicable to object shape measurement devices that achieve high-precision, high-speed imaging not only with visible light, but also with wavelengths outside the visible range, such as X-rays and ultraviolet light, which have high energy levels and are difficult to increase the output to achieve high image quality, as well as terahertz light and short-wavelength infrared light, for which it is difficult to put two-dimensional image sensors to practical use.As a result, in the future it will be possible to provide object shape measurement devices that can evaluate cells, bacteria, and semiconductor microstructures. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram showing an example of an overall system configuration including an object shape measuring apparatus according to an embodiment; [Figure 2] FIG. 2 is a software configuration diagram of the object shape measuring apparatus according to the embodiment. [Figure 3]1A and 1B are diagrams illustrating the principle of a measurement method that is a main technology of an object shape measurement apparatus according to an embodiment. [Figure 4] 10A to 10C are diagrams showing a method for creating a hologram recording medium used in the object shape measuring apparatus according to the embodiment. [Figure 5] 10A to 10C are diagrams showing a method of forming an object beam used in the object shape measuring apparatus according to the embodiment. [Figure 6] 3A and 3B are diagrams showing an example of object light used in the object shape measuring apparatus according to the embodiment. [Figure 7] 1A and 1B are diagrams showing an example of a Hadamard pattern used in an object shape measurement apparatus according to an embodiment. [Figure 8] Flowchart for creating a hologram recording medium used in an object shape measuring apparatus according to an embodiment [Figure 9] 4 is a flowchart of a measurement method of the object shape measurement apparatus according to the embodiment. [Figure 10] 3 shows a specific recording optical system of the object shape measuring apparatus according to the embodiment. [Figure 11] 1 shows a specific reproduction optical system of an object shape measuring apparatus according to an embodiment. [Figure 12] FIG. 1 is a diagram showing the physical positions of specific optical system components of an object shape measurement apparatus according to an embodiment; [Figure 13] 10 shows the amplitude distribution and phase distribution of a target object to be reconstructed to demonstrate the effectiveness of the object shape measurement apparatus according to the embodiment. [Figure 14] 10 shows amplitude distribution and phase distribution of a reconstructed image for demonstrating the effectiveness of the object shape measurement apparatus according to the embodiment. [Figure 15] FIG. 10 is a diagram showing a case where reconstruction processing is performed by hardware. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The same components are designated by the same reference numerals throughout the drawings, and duplicated explanations will be omitted. In the following embodiments, an object shape measurement device according to the present invention will be described as an example.

[0013] FIG. 1 is a diagram showing an example of the overall configuration including an object shape measurement apparatus 1 according to an embodiment of the present invention. In the object shape measurement apparatus 1 shown in FIG. 1, the target object 4 is shown as being light-transmitting, but this is not limited thereto and a reflective type may also be used. This object shape measurement apparatus 1 is composed of two functional elements: an optical system 2 and a system control and processing function 10. Each function is described in detail below. In the optical system 2, light irradiated from a light source 3 emitting a single-wavelength green laser, for example, is incident on the target object 4. While a green laser is used in the above description, this is not limiting and a single-wavelength red or blue laser may also be used. The light then passes through a first lens 5, a hologram recording medium 6, and a second lens 7, then passes through a spatial filter 8. The transmitted light is converted into an electrical signal by a photodetector 9 and input to a CPU 11. A detailed description of the functions, including the operation of the optical system 2, will be given later.

[0014] The system control and processing function 10 controls the operation of each of the above functions and performs calculations. It is composed of a CPU 11, ROM 12, RAM 13, external memory 14, and system bus 17. Other components include a drive unit 15 for driving the hologram recording medium 6 and a display unit 16 for displaying detailed images of the target object 4. The CPU 11 turns the power on and off for the light source 3 in the optical system 2, performs detailed control of the drive unit 15, sets various settings, controls the program for image processing calculations of the target object (described below), and sets various commands. The ROM 12 stores system software, processing calculation programs, and their initial values. The RAM 13 is a memory space for executing various software programs run by the CPU 11, or for storing data and settings temporarily recorded during calculations. The external memory 14 is memory for storing data that cannot be stored in the ROM 12 or RAM 13, as well as previous data. It can also be used to store software updates and new settings. Image data of the target object 4 processed and calculated by the CPU 11 (described below) is displayed on the display unit 16. These data are transmitted and received via a system bus 17. Although not shown in Fig. 1, the data may be transmitted and received externally via a network. FIG. 2 is a diagram showing the software configuration of the object shape measuring device 1 of this embodiment, which is made up of a CPU 11, a ROM 12, a RAM 13, an external memory 14, and a system bus 17.

[0015] The CPU 11 is a microprocessor unit that controls the entire object shape measuring apparatus 1 in accordance with a predetermined program. The system bus 17 is a data communication path for transmitting and receiving data between the CPU 11 and each part within the object shape measuring apparatus 1.

[0016] ROM (Read Only Memory) 12 is a memory that stores basic operating programs such as an operating system and other application programs. For example, a rewritable ROM such as an EEPROM (Electrically Erasable Programmable ROM) or flash ROM is used, and by updating the programs stored in ROM 12, it is possible to upgrade or expand the functionality of the basic operating programs and other application programs.

[0017] RAM (Random Access Memory) 13 serves as a work area when the basic operation program and other application programs are executed. Specifically, for example, a basic operation program 12a stored in ROM 12 is loaded into RAM 13, and the CPU 11 executes the loaded basic operation program to form a basic operation execution unit 13a. For ease of explanation, the process in which the CPU 11 loads the basic operation program 12a stored in ROM 12 into RAM 13 and executes it to control each unit will be described below as if the basic operation execution unit 13a controls each unit. Note that similar descriptions will be used for other application programs.

[0018] Image processing execution unit 13b performs various software processes on the electrical signals converted from the light intensity by photodetector 9 to correct brightness and color, etc., which are expressed as the level of the electrical signal, as well as edge processing, image quality improvement processing, noise removal processing, etc., to make the electrically converted image clearer. Details of reconstruction calculation execution unit 13c will be described later. Setting value execution unit 13d for various components controls various setting values ​​and sets initial values ​​for light source 3, drive device 15 that drives hologram recording medium 6, photodetector 9, and display unit 16. Image display execution unit 13e performs processing to display a detailed image of target object 4 on display unit 16 based on data calculated by reconstruction calculation execution unit 13c, which will be described later. Temporary storage area 13f is an area for temporarily storing data, etc., during each of the above-mentioned processes.

[0019] 2, the operation of the object shape measuring apparatus 1 of this embodiment is controlled by an image processing execution unit 13b, a reconstruction calculation execution unit 13c, a setting value execution unit 13d for various components, and an image display execution unit 13e, which are executed by the CPU 11 after the image processing program 14b, a reconstruction calculation program 14c, a setting program 14d for various components, and an image display execution unit 13e, which are stored mainly in an external memory 14, are expanded in RAM 13. The various information / data storage area 14a is an area for storing initial values ​​of various functions, etc. The image processing execution unit 13b, the reconstruction calculation execution unit 13c, the setting value execution unit 13d for various components, and the image display execution unit 13e may be partially or entirely performed by hardware blocks that are implemented by hardware.

[0020] The ROM 12 and RAM 13 may be integrated with the CPU 11. The ROM 12 may not be an independent configuration as shown in Figure 2, but may use a partial storage area within the external memory 14. The RAM 13 is also provided with a temporary storage area for temporarily storing data as needed when various application programs are executed.

[0021] The external memory 14 may temporarily store information detected by the photodetector 9. It may also store various operation setting values ​​of the object shape measuring device 1, position information and various other information of the object shape measuring device 1, some or all of the data of images and information captured by the object shape measuring device 1, and other programs.

[0022] A portion of the external memory 14 may replace all or part of the functions of the ROM 12. Furthermore, the external memory 14 needs to retain the stored information even when power is not supplied to the object shape measuring device 1. Therefore, devices such as flash ROM, SSD (Solid State Drive), and HDD (Hard Disc Drive) are used.

[0023] Next, the basic technology of the present invention will be explained using mathematical expressions.

[0024] The optical system 2, including its operation, will be explained using Figure 3. The optical system 2 is composed of a light source 3 emitting a single wavelength, a target object 4, a first lens 5, a hologram recording medium 6 on which the intensity of the interference between the phase modulation pattern and the reference light (a hologram) is recorded, a second lens 7, a spatial filter 8, and a photodetector 9. This configuration is essentially the same as that of optical correlation single-pixel imaging (SPI). Hereinafter, the optical system 2 will be referred to as optical correlation SPI. As shown in Figure 3, the target object 4, hologram recording medium 6, spatial filter 8, and photodetector 9 are positioned at the focal lengths f of the first lens 5 and second lens 7, respectively, forming a 4f optical system. The flow of the optical system 2 (optical correlation SPI) in the object shape measurement device 1 of Figure 1 will be explained using Figure 3. The single-wavelength light emitted from the light source 3, which irradiates light of a single wavelength such as a laser, is phase-modulated by passing through the target object 4 depending on the refractive index distribution of the target object 4. By passing this phase-modulated single-wavelength light through hologram recording medium 6 on which a hologram is recorded, diffracted light is emitted from hologram recording medium 6 as a correlation between object 4 and the phase modulation pattern. Finally, this diffracted light passes through spatial filter 8 with pinholes at appropriate positions, and the intensity of the diffracted light is acquired by photodetector 9. The acquired light intensity is used to perform reconstruction calculations in system control and processing function 10, making it possible to acquire a complex amplitude image of object 4.

[0025] Here, three processes, namely, the hologram recording process, correlation process, and reconstruction process, which are actually performed in the optical system 2 (optical correlation SPI), will be described.

[0026] The recording process is a process of recording the intensity of interference between the phase modulation pattern and the reference light as a hologram on the above-mentioned hologram recording medium 6. The principle of recording a hologram on the hologram recording medium 6 will be explained using Figure 4. The hologram recording process involves a second light source 20 that emits a single wavelength such as a laser similar to the light source 3 in Figure 3, the reference light emitted therefrom, a spatial light modulator 22 that can modulate phase and amplitude, object light of the same wavelength as the second light source 20 that is emitted from a third light source 21 that also emits a single wavelength such as a laser similar to the light source 3, a third lens 23, and a recording medium 24 on which a hologram is not recorded. As is clear from Figure 4, the spatial light modulator 22 and the recording medium 24 on which a hologram is not recorded are located at the focal length f of the third lens 23. Next, the hologram recording process in Figure 4 will be explained. First, the spatial light modulator 22 receives the phase modulation pattern p n The reference phase pattern a is a reference light for setting the reference phase of the phase modulation pattern. The phase modulation pattern has a phase shift e jφ where e is Napier's constant and j is the imaginary unit. An example of a phase modulation pattern and an example of a reference phase pattern are shown in Figure 5.

[0027] Light of a single wavelength emitted from the third light source 21 is passed through the spatial light modulator 22 on which this phase-shifted phase modulation pattern and reference phase pattern are displayed, and phase-modulated. A specific example is shown in Figure 5. The spatial light modulator 22 displays a phase modulation pattern (Figure 5(a)) and a reference phase pattern (Figure 5(b)), which is reference light for setting a reference phase for the phase modulation pattern. Light of a single wavelength emitted from the light source is passed through the spatial light modulator on which this phase-shifted phase modulation pattern and reference phase pattern are displayed, and phase-modulated (Figure 5(c)). The phase-modulated light is called object light u, and is described by the following equation:

[0028]

number

[0029] Next, the reference beam r and the object beam are made to interfere with each other and are focused to a single point by a lens, and then recorded as a hologram on the recording medium. The reference beam is emitted from a second light source 20, preferably a point light source. The recorded hologram I is described by the following equation:

[0030]

number

[0031] Next, the correlation process will be explained. The correlation process follows the flowchart shown in FIG. 9. The following explanation will be given with reference to FIG. 9. Light of a single wavelength is emitted from the light source 3 (S201). As mentioned above, this light is phase-modulated depending on the refractive index distribution of the target object 4 (S202). This phase-modulated light is designated as o, and the region of the target object 4 to be imaged is designated as o. t , and the other areas o When written as above, o is written as follows:

[0032]

number

[0033]

number

[0034]

number

[0035] Finally, the reconstruction process is shown. In the reconstruction process, the system control and processing function 10 performs reconstruction calculations based on the light intensity obtained by the photodetector 9. The phase modulation pattern is phase shifted multiple times to obtain the corresponding light intensity, and here four phase shifts (φ=0, π / 2, π, 3π / 2) are performed. The light intensity obtained for each phase shift is called I n,0 , I n,π / 2 , I n,π , I n,3π / 2 When the reconstructed image is recon is described by the following equation:

[0036]

number

[0037] The results of an investigation conducted to clarify the effects of the above-described embodiment are presented below. The optical systems shown in Figures 10, 11, and 12 are shown as examples of embodiments, and the method will be described using these figures. Figure 10 shows the optical system used during recording. During recording, light emitted from a light source (laser) 3 passes through a shutter 41, a half-wave plate 36, two mirrors M, a polarizing beam splitter (PBS) 35, and a beam expander (BE) 34, is narrowed by an aperture 37, is reflected by the half-wave plate 36, and mirror M32, passes through 32, and is reflected by a non-polarizing beam splitter (NPBS) 38 before entering a spatial light modulator (SLM) 22. Here, the spatial light modulator 22 simultaneously displays a pattern that will become the object beam and a pattern that will become the reference beam. Therefore, while Figure 4 shows that the reference light and object light are emitted from two light sources (second light source 20 and third light source 21) with equal wavelengths, and the object light pattern is created by spatial light modulator 22, Figure 10 shows that a single light source 3 enters spatial light modulator 22, and point light sources that become the object light pattern and reference light are emitted from spatial light modulator 22. The light then passes through non-polarizing beam splitter (NPBS) 38 and the various optical components shown in Figure 10 (omitted below) before being irradiated onto the holographic recording medium and recording a hologram. Figure 11 shows the optical system used during playback. During playback, light emitted from light source (laser) 3 passes through shutter 41, half-wave plate 36, two mirrors M, polarizing beam splitter (PBS) 35, and beam expander (BE) 34, is narrowed by aperture 37, reflected by half-wave plate 36 and mirror M32, passes through 32, and is reflected by non-polarizing beam splitter (NPBS) 38 before entering spatial light modulator (SLM) 22. Here, the spatial light modulator 22 displays a pattern of the target object, and the light is irradiated from the spatial light modulator 22 as the target object, passes through a non-polarizing beam splitter (NPBS) 38, and then passes through the various optical components shown in FIG. 11 (not described below) before being irradiated onto the hologram recording medium. The irradiated target object light and diffracted light from the hologram recording medium on which a hologram has been recorded pass through or are reflected by the various optical components shown in FIG. 11 (not described below), pass through a pinhole 39, and enter a photomultiplier tube (PMT) 40. The light shown by the dotted line is the first-order diffracted light returning from the hologram disc.The pinhole 39 is shown to distinguish it from the zeroth-order diffracted light (solid line) entering the photomultiplier tube 40. This pinhole 39 is the spatial filter 8 shown in Figure 3, and the photomultiplier tube 40 is the photodetector 9 shown in Figure 3. A feature of the present invention is that the object light pattern to be recorded on the holographic recording medium is created and displayed using the spatial light modulator 22, and the pinhole-type spatial filter 8 is placed in front of the photodetector 9. This makes it possible to accurately acquire phase and amplitude information of the target object. Figure 12 shows the relationship between the arrangement of each optical component, the focal length f, and the Fourier plane. In this figure, the symbols used to explain each optical component have been omitted to clarify the positional relationship. The focal length f of each lens 31 in Figures 10 and 11 is as shown in Figure 12, and each component is positioned at the focal length position shown in Figure 12. The relationship between the position of each component and the Fourier plane is also shown in Figure 12.

[0038] Next, Figures 13 and 14 show the results of a simple simulation of the amplitude and phase distributions of the object to be reconstructed, and the amplitude and phase distributions of the reconstructed image. In the simulation, the reference light was used as a point light source and expressed as a Gaussian distribution, and taking into consideration the full width at half maximum of this Gaussian distribution and the size of the pinhole opening of the spatial filter that only passes first-order light, we referenced the reconstructed image when the full width at half maximum was 1 pixel and the pinhole size was 1 x 1 pixel. Evaluation was also performed using RMSE. A smaller RMSE value indicates higher accuracy of reconstruction. We confirmed that the RMSE for the amplitude distribution was 0.07613, and the RMSE for the phase distribution was 0.00979, demonstrating high accuracy of reconstruction.

[0039] In the above, various experimental results, study results, sample shapes, etc. are quantified to explain the effects of the present invention, but the above quantification is merely an example, and various shapes can be used depending on the size and shape of the object in question.

[0040] In the above description, the process of actually acquiring light intensity and performing reconstruction calculations based on that data is described in FIG. 2 as being performed by software within the system control and processing function 10 in FIG. 1. However, for example, part or all of the recalculation processing unit, as shown in FIG. 15, may be configured with hardware. In FIG. 15, various processes are performed on the electrical signals converted from light intensity by the photodetector 9. Specifically, image processing 42 corrects the brightness and color expressed as the electrical signal level, performs edge processing to make the converted image clearer, performs image quality improvement processing, and performs noise reduction processing to convert the data into appropriate values. Reconstruction calculation 43 is then performed, followed by image display processing 44 to display an image of the target object 4. While the above description describes a case where 1,024 holograms are recorded on a holographic recording medium, there are cases where more holograms are recorded on the recording medium for higher accuracy and speed. Therefore, the reconstruction calculation unit may be configured with hardware to significantly improve processing speed. [Explanation of symbols]

[0041] 1: Object shape measuring device, 2: Optical system, 3: Light source (laser), 4: Target object, 5: First lens, 6: Hologram recording medium, 7: Second lens, 8: Spatial filter, 9: Photodetector, 10: System control and processing function, 11: CPU, 12: ROM, 13: RAM, 14: External memory, 15: Drive unit, 16: Display unit, 17: System bus, 20: Second light source, 21: Third light source, 22: Spatial light modulator (SLM), 23: Third lens, 24: recording medium without hologram recorded, 31: lens L, 32: mirror M, 33: objective lens, 34: beam expander (BE), 35: polarizing beam splitter (PBS), 36: half-wave plate (HWP), 37: aperture, 38: non-polarizing beam splitter (NPBS), 39: pinhole, 40: photomultiplier tube (PMT), 41: shutter, 42: image processing, 43: reconstruction calculation, 44: image display processing

Claims

1. a first optical element that converges parallel light of a single wavelength that is emitted from a light source and incident on a target object and that is transmitted through or reflected by the target object; a recording medium that is arranged at a focal position of the first optical element, and diffracts and outputs light converged by the first optical element using a hologram in which interference fringes of a plurality of modulation patterns in which the modulation states of the unit modulation elements are different from each other are arranged, the interference fringes being interference fringes of a reference light and object light modulated by a two-dimensional spatial light modulation unit in which unit modulation elements are arranged two-dimensionally; a second optical element that converges the light emitted from the recording medium; a third optical element that is disposed at a focal length of the second optical element, has an aperture having a size equal to the size of the unit modulation element of the two-dimensional spatial light modulation unit, and transmits primary light of the light converged by the second optical element through the aperture; a light detection unit that detects the intensity of light transmitted through the third optical element; An object shape measuring device comprising:

2. The modulation patterns include a first phase modulation pattern having a first phase difference from a reference phase pattern, and a second phase modulation pattern having a second phase difference from the first phase modulation pattern that is different from the phase difference from the reference phase pattern; In the hologram, the interference fringes are arranged at first positions where the interference fringes of the first phase modulation pattern are arranged, and at second positions where the interference fringes of the second phase modulation pattern are arranged. The object shape measuring device according to claim 1 .

3. A reconstruction unit that calculates a complex value including a correlation between a signal pattern and the target object based on the intensity of the light detected by the light detection unit, and reconstructs a complex amplitude image of the target object based on the calculated complex value; a display control unit that displays a three-dimensional object by performing light propagation calculation on the reconstructed complex amplitude image; The object shape measuring apparatus according to claim 1 , further comprising:

4. A method of converging a single-wavelength parallel light beam emitted from a light source and incident on a target object, the light beam being transmitted through or reflected by the target object, by a first optical element; A recording medium is arranged at a focal position of the first optical element, and the light converged by the first optical element is diffracted and emitted by a recording medium that is a hologram on which interference fringes of a plurality of modulation patterns, which are interference fringes of a reference light and an object light modulated by a two-dimensional spatial light modulation unit in which unit modulation elements are arranged two-dimensionally, and in which modulation states of the unit modulation elements are different from each other, are arranged. converging the light emitted from the recording medium by a second optical element; a third optical element that is arranged at a focal length of the second optical element, has an aperture having a size equal to the size of the unit modulation element of the two-dimensional spatial light modulation unit, and transmits primary light of the light converged by the second optical element through the third optical element having the aperture; detecting the intensity of the light transmitted through the third optical element by a light detection unit; An object shape measurement method comprising:

Images