Signal processing method, information processing device, optical coherence tomography device, and program

Abstract

To provide a technology for acquiring the shape of an interface with a high degree of diffusion. [Solution] This signal processing method is a signal processing method executed by an information processing device having a control unit, in which the control unit inputs an optical coherence tomography signal obtained by optical coherence tomography, identifies a target signal region in the optical coherence tomography signal that corresponds only to a first interface between a first layer group including one or more layers and a second layer group including one or more layers, and a second interface between the second layer group and a third layer group including one or more layers, and outputs information regarding the shape of the second interface obtained based on the target signal region.

Description

Technical Field

[0001] The present disclosure relates to a signal processing method, an information processing apparatus, an optical coherence tomography apparatus, and a program.

Background Art

[0002] Optical Coherence Tomography (OCT) is used in the medical field for tomography of living organs such as eyeballs.

[0003] For example, Patent Document 1 discloses an optical coherence tomography apparatus including an objective lens that condenses light from a light source onto a sample, and through which both sample light, which is reflected light from the sample, and reference light, which is reflected light from a reference surface provided between the objective lens and the sample, pass. Further, Patent Document 2 discloses an optical coherence tomography apparatus using a high-speed wavelength sweeping light source as a light source.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The present disclosure provides a technique for accurately acquiring information regarding the shape of an interface with a high degree of diffuseness.

Means for Solving the Problems

[0006] The signal processing method according to the first aspect is a signal processing method executed by an information processing apparatus having a control unit, wherein the control unit inputs an optical coherence tomography signal obtained by optical coherence tomography, In the optical coherence tomography signal, a target signal region is identified that corresponds only to the second interface among the first interface between a first group of layers containing one or more layers and a second group of layers containing one or more layers, and the second interface between the second group of layers and a third group of layers containing one or more layers. This is a signal processing method that outputs information regarding the shape of the second interface, which is obtained based on the target signal region.

[0007] According to the signal processing method of the first perspective, by identifying the target signal region corresponding only to the second interface in the optical coherence tomography signal, information regarding the shape of the second interface, which has a high degree of diffusion, can be obtained with high accuracy.

[0008] The signal processing method from the second perspective is: The control unit, In the target signal region, the first peak position with the highest signal intensity in the stacking direction in which the first layer group, the second layer group, and the third layer group are stacked is identified. This is a signal processing method from a first perspective, which outputs information regarding the shape of the second interface based on the first peak position.

[0009] According to the signal processing method of the second perspective, by accurately identifying the first peak position of the signal intensity corresponding to the second interface, information regarding the shape of the second interface with a high degree of diffusion can be obtained with high accuracy.

[0010] The signal processing method from the third perspective is: The control unit is a signal processing method from a first or second perspective that corrects the distortion of the target signal region.

[0011] According to the signal processing method of the third perspective, by correcting the distortion of the target signal region, information regarding the shape of the second interface, which has a high degree of diffusion, can be obtained with high accuracy.

[0012] The signal processing method from the fourth perspective is: The control unit, In the optical coherence tomography signal, the reference signal region containing the first interface is identified, In the reference signal region, identify the second peak position with the highest signal intensity in the stacking direction in which the first layer group, the second layer group, and the third layer group are stacked. Based on the second peak position, obtain information regarding the shape of the first interface. A signal processing method from a third perspective, wherein the distortion of the target signal region is corrected by subtracting the shape of the first interface from the shape of the second interface.

[0013] According to the signal processing method from a fourth perspective, by correcting the distortion of the target signal region, information regarding the shape of the second interface with a strong degree of diffusion can be obtained with high precision.

[0014] The signal processing method from a fifth perspective is a signal processing method from any of the first to fourth perspectives, in which the control unit outputs information regarding the thickness of the third layer group.

[0015] According to the signal processing method from a fifth perspective, information regarding the thickness of the third layer group can be obtained. [[ID=2​​​​​​​​​​​​​​​​​​According to the signal processing method of the seventh aspect, in a laminated structure with low transmittance for light having a wavelength of 960 nm or more and 2000 nm or less, information regarding the shape of the second interface with a strong degree of diffusion can be obtained with high precision.

[0020] The signal processing method of the eighth aspect is The laminated structure includes a layer made of at least one of resin, metal oxide, metal, carbon, glass, ceramics, and cement, and is the signal processing method of the seventh aspect.

[0021] According to the signal processing method of the eighth aspect, in a laminated structure including a layer made of at least one of metal oxide, metal, carbon, glass, ceramics, and cement, information regarding the shape of the second interface with a strong degree of diffusion can be obtained with high precision.

[0022] The signal processing method of the ninth aspect is The third layer group includes a layer made of rust, and is the signal processing method of any one of the first aspect to the eighth aspect.

[0023] According to the signal processing method of the ninth aspect, information regarding the shape of the second interface with a strong degree of diffusion including rust can be obtained with high precision.

[0024] The signal processing method of the tenth aspect is The second layer group includes a layer made of paint, and is the signal processing method of any one of the first aspect to the ninth aspect.

[0025] According to the signal processing method of the tenth aspect, information regarding the shape of the second interface with a strong degree of diffusion between the paint and the metal can be obtained with high precision.

[0026] The signal processing method of the eleventh aspect is The first layer group includes a layer of gas or liquid, and is the signal processing method of any one of the first aspect to the tenth aspect.

[0027] According to the signal processing method of the 11th perspective, when the first layer group includes a gas or liquid layer, information regarding the shape of the second interface with a high degree of diffusion can be obtained with high accuracy.

[0028] The information processing device from the 12th perspective is: An information processing device having a control unit, The control unit, By inputting the optical coherence tomography signal obtained by optical coherence tomography, In the optical coherence tomography signal, a target signal region is identified that corresponds only to the second interface among the first interface between a first group of layers containing one or more layers and a second group of layers containing one or more layers, and the second interface between the second group of layers and a third group of layers containing one or more layers. This is an information processing device that outputs information regarding the shape of the second interface, which is acquired based on the target signal region.

[0029] According to the information processing device described in the 12th perspective, by identifying the target signal region corresponding only to the second interface in the optical coherence tomography signal, information regarding the shape of the second interface with a high degree of diffusion can be obtained with high accuracy.

[0030] From the 13th perspective, the optical coherence tomography (OCT) system is Information processing device from the 12th perspective, This optical coherence tomography (OCT) apparatus includes a signal acquisition device that acquires the optical coherence tomography signal of a stacked structure by optical coherence tomography.

[0031] According to the optical coherence tomography (OCT) system described in the 13th perspective, by identifying the target signal region corresponding only to the second interface in the OCT signal, information regarding the shape of the second interface, which has a high degree of diffusion, can be obtained with high accuracy.

[0032] From the 14th perspective, the optical coherence tomography (OCT) system is The signal acquisition device is an optical coherence tomography (OCT) device from the 13th perspective, which emits light with a wavelength of 960 nm to 2000 nm.

[0033] According to the optical coherence tomography (OCT) system described in the 14th perspective, by using light with a wavelength of 960 nm to 2000 nm, it is possible to obtain highly accurate information about the shape of the second interface with a high degree of diffusion in a laminated structure composed of layers of various materials.

[0034] From the 15th perspective, the optical coherence tomography (OCT) system is The signal acquisition device is an optical coherence tomography apparatus according to the 13th or 14th viewpoint, which emits linearly polarized, circularly polarized, or elliptically polarized light.

[0035] According to the optical coherence tomography (OCT) system described in the 15th perspective, by using linearly polarized, circularly polarized, or elliptically polarized light, it is possible to obtain highly accurate information regarding the shape of the second interface with a high degree of diffusion in a laminated structure composed of layers of various materials.

[0036] From the 16th perspective, the optical coherence tomography (OCT) system is The control unit of the information processing device has By inputting the optical coherence tomography signal obtained by optical coherence tomography, Of the first interface between a first group of layers containing one or more layers and a second group of layers containing one or more layers, and the second interface between the second group of layers and a third group of layers containing one or more layers, the target signal region corresponding only to the second interface is identified. This is a program that performs processing to output information about the shape of the second interface, which is obtained based on the target signal region.

[0037] According to the program of the 16th perspective, by identifying the target signal region corresponding only to the second interface in the optical coherence tomography signal, it is possible to obtain information about the shape of the second interface with a high degree of diffusion based on the optical coherence tomography signal with high accuracy. [Brief explanation of the drawing]

[0038] [Figure 1] This is a schematic diagram of an optical coherence tomography apparatus having an information processing device according to the first embodiment. [Figure 2]This is a block diagram showing the hardware configuration of the information processing device according to the first embodiment. [Figure 3] This is a block diagram showing the functional configuration of the information processing device according to the first embodiment. [Figure 4] This is a schematic cross-sectional view of a laminated structure containing metal material, paint, and rust. [Figure 5] This is a schematic diagram of the optical coherence tomography signal and signal intensity obtained at an interface with a high degree of diffusion. [Figure 6] This is a schematic diagram of the optical coherence tomography signal and signal intensity obtained at an interface with a low degree of diffusion. [Figure 7] This figure shows the optical coherence tomography signal of a stacked structure including the first interface and the second interface. [Figure 8] This figure shows the target signal region corresponding only to the second interface and its first peak position. [Figure 9] This figure shows the results of obtaining information regarding the shape of the second interface, including rust. [Figure 10] This figure shows the results of obtaining information regarding the shape of the second interface, which does not contain rust. [Figure 11] This is a flowchart showing the processing performed by the information processing device according to the first embodiment. [Figure 12] This is a block diagram showing the functional configuration of the information processing device according to the second embodiment. [Figure 13] This figure shows the shape of the first interface obtained with the information processing device according to the second embodiment. [Figure 14] This figure shows the shape of the second interface obtained with the information processing device according to the second embodiment. [Figure 15] This figure shows the result of correcting distortion by subtracting the information regarding the shape of the first interface in Figure 13 from the information regarding the shape of the second interface in Figure 14. [Figure 16] This is a flowchart showing the processing performed by the information processing device according to the second embodiment. [Modes for carrying out the invention]

[0039] The embodiments for implementing this disclosure will be described in detail below with reference to the drawings. However, the embodiments shown below are illustrative of signal processing methods, information processing devices, optical coherence tomography apparatuses, and programs for realizing the technical concept of the embodiments of this disclosure, and are not limited to those described below. Note that the size, positional relationships, etc. of the components shown in each drawing may be exaggerated for clarity of explanation. In each drawing, the same components are denoted by the same reference numerals, and redundant explanations are omitted as appropriate.

[0040] In drawings, the XYZ Cartesian coordinate system may be used to represent direction. The Z direction, along the Z axis, corresponds to the stacking direction of each layer of the stacked structure to be imaged in an optical coherence tomography (OCT) apparatus having an information processing device according to the embodiment. The Z direction also corresponds to the direction along the optical axis of the probe optical system of the OCT apparatus. The galvanometer mirror of the OCT apparatus scans light in the XY direction.

[0041] In this specification, for the sake of simplicity, "optical coherence tomography" will be referred to as OCT (Optical Coherence Tomography), "optical coherence tomography method" will be referred to as the OCT method, and an optical coherence tomography device will be referred to as an OCT device.

[0042] [First Embodiment] <Configuration of an OCT device having an information processing device according to the first embodiment> Figure 1 is a schematic diagram showing the configuration of an OCT device 100 having an information processing device 1 according to the first embodiment.

[0043] As shown in Figure 1, the OCT apparatus 100 includes an information processing device 1 that executes a signal processing method according to the first embodiment, and a signal acquisition device 2 that acquires an optical coherence tomography signal of a stacked structure by the OCT method. The OCT apparatus 100 also includes an operation device 3 that receives operation input to the OCT apparatus 100, and a display device 4 that displays an optical coherence tomography image generated by the information processing device 1. The signal acquisition device 2 includes a frequency scanning light source 101, a coupler 102, a circulator 103, a probe optical system 104, a galvanometer mirror driver 121, a variable optical attenuator 122, and a differential optical detection amplifier 123. The probe optical system 104 includes a collimator 105, a galvanometer mirror 106, an objective lens 107, and a reference member 108.

[0044] The OCT apparatus 100 performs tomographic imaging of the laminated structure 110, which is the sample, based on the interference between the sample light and the reference light. The sample light is the light that is reflected or scattered at the interlayer interfaces in the laminated structure 110 after passing through the objective lens 107 and the reference member 108 and irradiating the laminated structure 110. The reference light is the light that has passed through the objective lens 107 and then reflected by the reference surface 109 of the reference member 108. The reflected light includes specular reflection and diffuse reflection.

[0045] In this embodiment, the laminated structure 110 is a structure comprising a first layer group containing one or more layers, a second layer group containing one or more layers, and a third layer group containing one or more layers. The laminated structure 110 will be described in detail separately with reference to Figure 7. The optical coherence tomography signal is a signal obtained by performing a Fourier transform on the interference signal, which includes interference fringes between the sample light and the reference light. In this embodiment, the OCT apparatus 100 acquires information regarding the three-dimensional shape of the second interface between the first layer group and the second layer group by performing tomography of the laminated structure 110.

[0046] The frequency scanning light source 101 outputs light L0 used for OCT. The frequency scanning light source 101 outputs a trigger signal at the start of each frequency scan. The frequency scanning light source 101 also detects light using a Mach-Zehnder interferometer and outputs a K clock signal for sampling at equal frequency intervals. The light L0 output from the frequency scanning light source 101 is split in the coupler 102 into a first split beam L1 used to generate sample light and reference light, and a second split beam L2 used to remove the DC component of the interference signal, with an intensity ratio of 95:5. The first split beam L1 is input to port SP1 of the circulator 103, output from port SP2, and transmitted to the probe optical system 104 via an optical fiber.

[0047] In the example shown in Figure 1, the probe optical system 104 includes a Fizeau interferometer. However, the interferometer included in the probe optical system 104 is not limited to a Fizeau interferometer, as long as, in principle, both the sample light and the reference light can pass through the objective lens 107. The probe optical system 104 may also include other forms of interferometers, such as a Michelson interferometer or a Milow interferometer.

[0048] In the probe optical system 104 shown in Figure 1, the first segmented light L1 is converted into parallel light by the collimator 105, reflected by the galvanometer mirror 106, and incident on the objective lens 107. The galvanometer mirror 106 is driven by the galvanometer mirror driver 121 and scans the parallel light converted by the collimator 105 in the XY direction. The galvanometer mirror 106 may be a polygon mirror, a MEMS mirror, or the like.

[0049] Parallel light incident on the objective lens 107 passes through the reference member 108 and is focused onto the stacked structure 110, which is the object to be photographed. This light is then reflected from the sample surface and incident on the objective lens 107 as sample light. In addition, a portion of the parallel light incident on the objective lens 107 is reflected from the reference surface 109 of the reference member 108 and incident on the objective lens 107 as reference light.

[0050] The sample light and reference light incident on the objective lens 107 pass through the galvanometer mirror 106 and collimator 105, then are input to port SP2 of the circulator 103 via an optical fiber, output from port SP3, and then input to the differential optical detection amplifier 123. The differential optical detection amplifier 123 detects and amplifies the interference signal based on the interference of the sample light and reference light. The second split light L2, which is divided at the coupler 102, is attenuated by the variable optical attenuator 122 and then input to the differential optical detection amplifier 123.

[0051] The differential optical detection amplifier 123 uses the signal of the second divided light L2 to remove the DC component contained in the interference signal. The interference signal, after the DC component has been removed by the differential optical detection amplifier 123 and amplified, is collected by the DAQ device (A / D converter) of the information processing device 1 and converted into digital data. The collection of the interference signal is started by a trigger signal emitted by the frequency scanning light source 101 and is performed in synchronization with the K clock signal. An anti-aliasing filter is provided between the differential optical detection amplifier 123 and the DAQ device to attenuate unwanted frequency components that exceed the measurable distance.

[0052] The information processing device 1 generates an optical coherence tomography (OCT) signal by performing a Fourier transform on the interference signal converted by the DAQ device. The information processing device 1 also converts the generated OCT signal to 8 bits, i.e., 256 levels, and generates an OCT image composed of multiple pixels, each having 256 levels. The information processing device 1 transmits the generated OCT image of the stacked structure 110 to the display device 4.

[0053] The operating device 3 is an input interface that includes a keyboard with multiple keys for inputting characters, numbers, and various instructions, and a pointing device or mouse for selecting and executing various instructions, selecting processing targets, moving the cursor, etc. The display device 4 is a display that shows various information such as optical coherence tomography images received from the information processing device 1. The OCT device 100 may have a touch panel that integrates the operating device 3 and the display device 4.

[0054] A wavelength-swept laser using a wavelength-swept filter can be used as the frequency scanning light source 101. The wavelength-swept filter can be one that sweeps the wavelength by driving a polygon mirror or a galvanometer mirror. However, the frequency scanning light source 101 can also use an FDML (Fourier Domain Mode Locking) laser, a MEMS (Micro Electro Mechanical Systems) wavelength-swept light source, an SGDBR (Sampled Grating Distributed Bragg Reflector) laser, etc. Furthermore, for the MEMS wavelength-swept light source, a MEMS VCSEL (Vertical Cavity Surface Emitting Laser), an external cavity type MEMS Fabry-Perot laser, etc., can be used.

[0055] The light L0 output from the frequency scanning light source 101 is, for example, near-infrared light. Preferably, the light L0 has a central wavelength of 600 nm to 2000 nm. Among these, light with a central wavelength of 1060 ± 100 nm, 1310 ± 100 nm, 1550 ± 100 nm, or 1750 ± 100 nm is more preferred, considering the stability of the light source and the reliability of the sensor.

[0056] For the frequency scanning light source 101, for example, a high-speed wavelength-swept light source manufactured by Excelitas (center wavelength: 1310 nm, sweep width: 100 nm, A-scan rate: 50 kHz, output: 25 mW, coherence length: 12 mm) can be used.

[0057] The types of OCT that can be used in the OCT device 100 include time-domain OCT (TD-OCT), Fourier-domain OCT (FD-OCT), and polarization-sensitive OCT (PS-OCT). FD-OCT includes spectral-domain OCT (SD-OCT) and swept-source OCT (SS-OCT). Among these, SS-OCT is preferred due to its high sensitivity and deep measurable depth. Furthermore, high-resolution variations of FD-OCT include full-field (FF-OCT) and line-field confocal (LC-OCT).

[0058] <Hardware configuration of information processing device 1> Figure 2 is a block diagram showing the hardware configuration of the information processing device 1. As shown in Figure 2, the information processing device 1 comprises a control unit 11, a ROM (Read Only Memory) 12, and a RAM (Random Access Memory) 13. The information processing device 1 also includes an HDD (Hard Disk Drive) / SSD (Solid State Drive) 14, a DAQ device 15, an external I / F 16, and an operation unit 17. The control unit 11, ROM 12, RAM 13, HDD / SSD 14, DAQ device 15, external I / F 16, and operation unit 17 are each connected to bus B.

[0059] The control unit 11 is an arithmetic unit that reads programs from storage devices such as ROM 12 and HDD / SSD 14 onto RAM 13 and executes processing. The control unit 11 executes various processes by executing instruction codes stored in memory using electronic circuits, or by using electronic circuits designed for special purposes, thereby realizing the various functions of the information processing device 1. The electronic circuits are CPUs (Central Processing Units) or MPUs (Micro Processing Units). However, the electronic circuits may also be ASICs (Application Specific Integrated Circuits) or FPGAs (Field-Programmable Gate Arrays). The control unit 11, ROM 12, and RAM 13 constitute a computer that controls the OCT device 100.

[0060] ROM12 is a non-volatile semiconductor memory that can retain programs and other data even when the power is turned off. ROM12 stores information related to various settings, such as programs like the BIOS (Basic Input / Output System) executed at startup, OS (Operating System) settings, and network settings. RAM13 is a volatile semiconductor memory that temporarily holds programs, applications, and data. HDD / SSD14 is a non-volatile memory that stores data such as optical coherence tomography images.

[0061] The DAQ device 15 is an A / D (Analog-to-Digital) converter that collects an amplified optical coherence tomography signal, from which the DC component has been removed by the differential optical detection amplifier 123, and converts it into digital data.

[0062] External I / F16 is an interface that connects the signal acquisition device 2 and display device 4 to the information processing device 1. Through External I / F16, the information processing device 1 connects to devices other than itself. These other devices include the signal acquisition device 2, display device 4, PC (Personal Computer), server, etc.

[0063] <Functional configuration of the information processing device 1> The functional configuration of the information processing device 1 will be described with reference to Figures 3 to 10. Figure 3 is a block diagram showing the functional configuration of the information processing device 1. Figure 4 is a schematic cross-sectional view of a laminated structure containing a metal material 41, paint 42, and rust 43. Figure 5 is a schematic diagram of the optical coherence tomography signal and signal intensity obtained at an interface with a high degree of diffusion. Figure 6 is a schematic diagram of the optical coherence tomography signal and signal intensity obtained at an interface with a low degree of diffusion. Figure 7 is a diagram showing the optical coherence tomography signal of a laminated structure containing a first interface 114 and a second interface 115. Figure 8 is a diagram showing the target signal region Tg corresponding only to the second interface 115 and its first peak position Ps1. Figure 9 is a diagram showing the acquisition results of information regarding the shape of the second interface containing rust. Figure 10 is a diagram showing the acquisition results of information regarding the shape of the second interface without rust.

[0064] As shown in Figure 3, the information processing device 1 includes an input unit 20, a target signal region identification unit 21, a first peak position identification unit 22, a shape acquisition unit 23, and an output unit 24.

[0065] The functions of the input unit 20 and the output unit 24 are realized by an external I / F 16, or by the control unit 11 executing processing specified in a program stored in ROM 12 or the like. The functions of the target signal area identification unit 21, the first peak position identification unit 22, and the shape acquisition unit 23 are realized by the control unit 11 executing processing specified in a program stored in ROM 12 or the like. Some of the above functions of the information processing device 1 may be realized by devices other than the information processing device 1, such as a server, or may be realized by distributed processing between the information processing device 1 and devices other than the information processing device 1.

[0066] Here, for example, vehicles such as automobiles, or structures such as fences or guardrails, may be constructed as laminated structures by applying paint to the surface of a metal material, as shown in Figure 4. When metal oxides such as rust occur at the interface between the paint and the metal material in such laminated structures, the paint may peel off, impairing the appearance of the vehicle or structure, or the metal material may deteriorate, leading to a deterioration in the strength of the vehicle or structure. In the example shown in Figure 4, paint 42 is applied to the surface of a metal material 41, and rust 43 is schematically shown occurring between the metal material 41 and the paint 42. Understanding the occurrence of metal oxides at the interface between the paint and the metal material is effective from the viewpoint of maintaining the appearance and strength of vehicles and structures.

[0067] Since OCT equipment can acquire information about the three-dimensional shape of the interlayer interfaces in a laminated structure, it may be possible to understand the occurrence of metal oxides such as rust at the interface between paint and metal materials by using OCT equipment.

[0068] However, for example, as shown in Figure 5, if the shape of the interface 50 is rough and the degree of diffusion of incident light to the interface 50 is strong, the light L irradiated from the signal acquisition device 2X is multiple-scattered by the interface 50. This multiple scattering causes the optical path length of the returned light R to become non-uniform. When the returned light R with a non-uniform optical path length is detected by the differential optical detection amplifier 123, the width W1 of the signal region corresponding to the interface 50 in the optical coherence tomography signal Sg becomes wider, and the slope near the first peak P1 of the first signal intensity distribution S1 becomes gentler. On the other hand, as shown in Figure 6, if the shape of the interface 60 is smooth and the degree of diffusion of incident light to the interface 60 is weak, the light L irradiated from the signal acquisition device 2X is almost specularly reflected by the interface 50, and the optical path length of the returned light R becomes almost uniform. When a return light R with a uniform optical path length is detected by the differential optical detection amplifier 123, the width W2 of the signal region corresponding to the interface 60 in the optical coherence tomography signal Sg narrows, and the slope near the second peak P2 of the second signal intensity distribution S2 becomes steeper.

[0069] As shown in Figures 5 and 6, the width W1 of the signal region is wider than the width W2 of the signal region, and the slope near the first peak P1 of the first signal intensity distribution S1 is gentler compared to the slope near the second peak P2 of the second signal intensity distribution S2. Because the slope near the first peak P1 of the first signal intensity distribution S1 is gentle, the accuracy of identifying the position of the first peak P1 in the Z direction where paints, metal materials, etc. are layered is reduced, and as a result, the accuracy of acquiring information about the interface shape obtained based on the position of the first peak P1 may be reduced.

[0070] In this embodiment, as shown in Figures 3 and 7, the control unit 11 of the information processing device 1 receives the optical coherence tomography signal Sg obtained by the OCT method via the input unit 20. The control unit 11 identifies a target signal region Tg in the optical coherence tomography signal Sg that corresponds only to the second interface 115 among the first interface 114 between the first layer group 111 containing one or more layers and the second layer group 112 containing one or more layers, and the second interface 115 between the second layer group 112 and the third layer group 113 containing one or more layers, using the target signal region identification unit 21.

[0071] Furthermore, in this embodiment, as shown in Figures 3 and 8, the control unit 11 uses the first peak position identification unit 22 to identify the first peak position Ps1 with the highest signal intensity in the Z direction where the first layer group 111, the second layer group 112, and the third layer group 113 are stacked in the target signal region Tg. Based on the first peak position Ps1 identified by the first peak position identification unit 22, the control unit 11 uses the shape acquisition unit 23 to calculate and acquire information regarding the shape of the second interface 115. The control unit 11 uses the output unit 24 to output the information regarding the shape of the second interface 115 acquired by the shape acquisition unit 23 to a device other than the information processing device 1.

[0072] The first interface 114 is an interface located closer to the reference member 108 than the second interface 115. In other words, the first interface 114 is an interface located on the frequency scanning light source 101 side of the second interface 115. In the example shown in Figure 7, of the first layer group 111, the second layer group 112, and the third layer group 113 in the laminated structure 110, the first layer group 111 is located on the reference member 108 side. The second layer group 112 and the third layer group 113 are located further away from the reference member 108 in that order.

[0073] The optical coherence tomography (OCT) signal Sg is a signal with a dynamic range corresponding to more than 8 bits. More than 8 bits corresponds to 12 bits, 16 bits, etc. However, in the examples shown in Figures 7 and 8, for illustrative purposes, the OCT signal Sg is represented as an OCT image composed of multiple pixels, each having an 8-bit grayscale value.

[0074] The input unit 20 controls communication between the information processing device 1 and the signal acquisition device 2, thereby receiving the optical coherence tomography signal Sg obtained by the signal acquisition device 2 as input from the signal acquisition device 2.

[0075] In the identification of the target signal region Tg by the target signal region identification unit 21, for example, the OCT device 100 displays an optical coherence tomography (OCT) image corresponding to the optical coherence tomography signal Sg on the display device 4, as shown in Figure 7. The operator of the OCT device 100 moves a cursor on the display device 4 using an operating device 3, such as a mouse, while viewing the OCT image corresponding to the OCT signal Sg displayed on the display device 4, and selects an image region in the OCT image that includes only the second interface 115 and does not include the first interface 114. Information regarding the selected image region is passed from the operating device 3 to the information processing device 1. The target signal region identification unit 21 identifies the target signal region Tg by receiving information regarding the selected image region from the operating device 3 via the input unit 20. However, the method of identifying the target signal region Tg by the target signal region identification unit 21 is not limited to the method described above. For example, the target signal region identification unit 21 may perform image processing on the optical coherence tomography image corresponding to the optical coherence tomography signal Sg, thereby automatically recognizing the image region corresponding to the target signal region Tg within the optical coherence tomography image and identifying the target signal region Tg. In this case, selection by the operator using the operating device 3 is not required. The reference signal region Rf in Figure 7 will be explained in the second embodiment.

[0076] In Figure 8, the first signal intensity distribution S1 shown next to the target signal region Tg represents the signal intensity distribution along the Z direction in the target signal region Tg. The first peak position Ps1 is the position where the signal intensity of the second interface 115 peaks in the Z direction. The position of the first peak position Ps1 in the Z direction changes depending on the position in the X direction. The first peak position identification unit 22 identifies the first peak position Ps1 for each position in the X direction. The first peak position identification unit 22 also identifies the first peak position Ps1 for each position in the Y direction. The first peak position identification unit 22 passes the identified first peak position Ps1 to the shape acquisition unit 23.

[0077] The shape acquisition unit 23 connects the first peak positions Ps1 received from the first peak position identification unit 22 along the XY direction and converts them into height data corresponding to the shape. Through this, the shape acquisition unit 23 obtains information regarding the three-dimensional shape of the second interface 115 through calculation. Note that the process of connecting the first peak positions Ps1 along the XY direction may also be performed by a unit other than the shape acquisition unit 23, such as the first peak position identification unit 22.

[0078] The output unit 24 controls communication between the information processing device 1 and other devices, thereby outputting information regarding the three-dimensional shape of the second interface 115 to devices other than the information processing device 1.

[0079] Figures 9 and 10 show the three-dimensional shape of the second interface 115. In the example shown in Figure 9, rust is present in the second interface 115, resulting in irregularities corresponding to the rust. On the other hand, in the example shown in Figure 10, the second interface 115 contains almost no rust, so there are almost no irregularities corresponding to the rust.

[0080] In this embodiment, the target signal region Tg identified by the target signal region identification unit 21 is narrower than the region corresponding to the entire optical coherence tomography signal Sg. Therefore, the first peak position identification unit 22 can identify the first peak position Ps1 with higher accuracy compared to the case where the first peak position Ps1 of the first signal intensity distribution S1 is determined from information of the region corresponding to the entire optical coherence tomography signal Sg. In this embodiment, information regarding the shape of the second interface 115 can be acquired with higher accuracy by acquiring information regarding the shape of the second interface 115 based on the target signal region Tg. Furthermore, in this embodiment, by identifying the target signal region Tg, information regarding the shape of the first interface 114 and information regarding the shape of the second interface 115 can be acquired separately.

[0081] In this embodiment, the optical coherence tomography signal Sg is a signal with a dynamic range corresponding to more than 8 bits. Therefore, the first peak position identification unit 22 can identify the first peak position Ps1 with higher accuracy compared to the case where information about the shape of the second interface 115 is acquired based on an 8-bit optical coherence tomography image. As a result, in this embodiment, information about the shape of the second interface 115 can be acquired with higher accuracy. The accuracy of identifying the first peak position Ps1 based on the optical coherence tomography signal Sg depends on the data interval in the FFT (Fast Fourier Transform) calculation, and the larger the FFT size, the higher the identification accuracy.

[0082] In this embodiment, the first layer group 111 includes only an air layer. The second layer group 112 includes a layer made of paint. The third layer group 113 includes a layer made of rust. In this embodiment, even with the first layer group 111, the second layer group 112, and the third layer group 113 as described above, information regarding the shape of the second interface 115 can be obtained with high accuracy. However, the first layer group 111 is not limited to only an air layer, but may include multiple layers of different types of gases. Also, the first layer group 111 may include only a liquid layer, or it may include multiple layers of different types of liquids, or it may include one or more gas layers and one or more liquid layers. The liquid included in the first layer group 111 is a liquid having a refractive index approximately the same as that of the second layer group 112, used to reduce reflection at the first interface 114. Also, the second layer group 112 may include multiple layers of different types of paints.

[0083] In this embodiment, the laminated structure 110, which includes a second layer group 112 and a third layer group 113, has a transmittance of 20% or less for light with a wavelength of 960 nm to 2000 nm. In this embodiment, information regarding the shape of the second interface with a high degree of diffusion can be obtained with high accuracy in a laminated structure with low transmittance for light with a wavelength of 960 nm to 2000 nm.

[0084] In this embodiment, the laminated structure 110 includes a layer made up of at least one of resin, metal oxide, metal, carbon, glass, ceramics, and cement. In this embodiment, even with such a laminated structure 110, information regarding the shape of the second interface 115 can be obtained with high accuracy.

[0085] In this embodiment, it is preferable that the signal acquisition device 2 emits light with a wavelength of 960 nm to 2000 nm. By using light with a wavelength of 960 nm to 2000 nm, it is possible to acquire information regarding the shape of the second interface, which has a high degree of diffusion, with high accuracy in a laminated structure composed of layers of various materials.

[0086] In this embodiment, the signal acquisition device 2 may emit linearly polarized, circularly polarized, or elliptically polarized light. By using linearly polarized, circularly polarized, or elliptically polarized light, information regarding the shape of the second interface with a high degree of diffusion can be acquired with high accuracy in a laminated structure composed of layers of various materials.

[0087] <Processing by Information Processing Device 1> Figure 11 is a flowchart showing the processing performed by the information processing device 1. The information processing device 1 starts the processing shown in Figure 11 when it receives an optical coherence tomography signal Sg via the input unit 20 as a starting condition. The optical coherence tomography signal Sg that the information processing device 1 inputs as a starting condition refers to the optical coherence tomography signal Sg corresponding to the entire optical coherence tomography image shown in Figure 7.

[0088] First, in step S11, the information processing device 1 uses the target signal region identification unit 21 to identify a target signal region Tg in the optical coherence tomography signal Sg that corresponds only to the second interface 115 out of the first interface 114 and the second interface 115. The target signal region identification unit 21 then passes the information regarding the identified target signal region Tg to the first peak position identification unit 22.

[0089] Next, in step S12, the information processing device 1 uses the first peak position identification unit 22 to identify the first peak position Ps1 with the highest signal intensity in the Z direction within the target signal region Tg. The first peak position identification unit 22 identifies the two-dimensional distribution of the first peak position Ps1 across the entire second interface 115 along the X and Y directions. The first peak position identification unit 22 then passes the information regarding the identified two-dimensional distribution of the first peak position Ps1 to the shape acquisition unit 23.

[0090] Next, in step S13, the information processing device 1 uses the shape acquisition unit 23 to connect the first peak positions Ps1 along the XY direction and convert them into height data corresponding to the shape, thereby acquiring information about the three-dimensional shape of the second interface 115. The shape acquisition unit 23 then passes the acquired information about the three-dimensional shape of the second interface 115 to the output unit 24.

[0091] Next, in step S14, the information processing device 1 outputs information regarding the three-dimensional shape of the second interface 115 to a device other than the information processing device 1 via the output unit 24.

[0092] As described above, the information processing device 1 can acquire information regarding the three-dimensional shape of the second interface 115 of the stacked structure 110 and output it to a device other than the information processing device 1.

[0093] [Second Embodiment] Next, an information processing apparatus according to the second embodiment will be described. Note that names and reference numerals identical to those used in the previously described embodiments indicate the same or identical components or configurations, and detailed explanations will be omitted as appropriate.

[0094] <Functional configuration of the information processing device according to the second embodiment> The functional configuration of the information processing device according to the second embodiment will be described with reference to Figures 12 to 15. Figure 12 is a block diagram showing the functional configuration of the information processing device 1a according to the second embodiment. Figure 13 is a diagram showing the shape of the first interface 114 obtained by the information processing device 1a. Figure 14 is a diagram showing the shape of the second interface 115 obtained by the information processing device 1a. Figure 15 is a diagram showing the result of correcting distortion by subtracting the information regarding the shape of the first interface 114 in Figure 13 from the information regarding the shape of the second interface 115 in Figure 14.

[0095] As shown in Figure 12, the information processing device 1a includes a reference signal area identification unit 25, a second peak position identification unit 26, a correction unit 27, a thickness acquisition unit 28, and a storage unit 29.

[0096] The functions of the storage unit 29 can be realized by an HDD / SSD 14 or the like. The functions of the reference signal area identification unit 25, the second peak position identification unit 26, the correction unit 27, and the thickness acquisition unit 28 can be realized by the control unit 11 executing processing defined in a program stored in a ROM 12 or the like. Some of the above functions of the information processing device 1a may be realized by devices other than the information processing device 1a, such as a server, or may be realized by distributed processing between the information processing device 1a and devices other than the information processing device 1a.

[0097] Here, for example, in a typical OCT device, distortion of the optical interference image signal may occur. Distortion of the optical interference image signal refers to spatial distortion of the optical interference image signal due to various factors. These various factors include the tilt of the stacked structure when it is installed, due to the stacked structure being tilted relative to the objective lens. Other various factors include deviations from a predetermined distance in the Z-direction along the optical axis of the objective lens between the objective lens and the stacked structure, or aberrations of the objective lens. When distortion occurs in the optical interference image signal, shape errors occur in the acquired information about the shape of the interface, corresponding to the tilt of the stacked structure and aberrations of the objective lens. This can reduce the accuracy of acquiring information about the shape of the interface.

[0098] In this embodiment, the control unit 11 of the information processing device 1a corrects the distortion of the target signal region Tg using the correction unit 27. For example, the control unit 11 uses the reference signal region identification unit 25 to identify the reference signal region Rf (see Figure 7) in the optical coherence tomography signal Sg that includes the first interface 114. The method for identifying the reference signal region Rf by the reference signal region identification unit 25 is the same as the method for identifying the target signal region Tg by the target signal region identification unit 21. The control unit 11 uses the second peak position identification unit 26 to identify the second peak position Ps2 in the reference signal region Rf where the first layer group 111, the second layer group 112, and the third layer group 113 are stacked, and where the signal intensity is highest. The control unit 11 uses the shape acquisition unit 23 to acquire information about the shape of the first interface 114 based on the second peak position Ps2. The control unit 11 corrects the distortion of the target signal region Tg by subtracting the shape of the first interface 114 from the shape of the second interface 115 using the correction unit 27.

[0099] Assuming that the thickness of the second layer group 112 is nearly uniform, the shape of the first interface 114 between the first layer group 111 and the second layer group 112 is considered to be approximately equal to the distortion of the target signal region Tg. The correction unit 27 obtains information about the shape of the second interface 115 after correcting the distortion of the target signal region Tg by subtracting the shape of the first interface 114 from the shape of the second interface 115. By correcting the distortion of the target signal region Tg, information about the shape of the second interface 115 can be obtained with high accuracy in this embodiment. The thickness of the second layer group 112 corresponds to the length of the second layer group 112 in the Z direction.

[0100] Figure 13 shows an example of the shape of the first interface 114 acquired by an OCT device having an information processing device 1a. Figure 14 shows an example of the shape of the second interface 115 acquired by an OCT device having an information processing device 1a. In the examples shown in Figures 13 and 14, the laminated structure 110 is installed at an angle with respect to the objective lens, and the tilt error of the laminated structure 110 is included in the shapes of the first interface 114 and the second interface 115. The correction unit 27 reduces the tilt error from the second interface 115 by subtracting the shape of the first interface 114 from the shape of the second interface 115. As a result, as shown in Figure 15, highly accurate information regarding the shape of the second interface 115 with reduced tilt error is obtained.

[0101] In this embodiment, as shown in Figure 12, the control unit 11 obtains information regarding the thickness of the third layer group 113 by calculation using the thickness acquisition unit 28. For example, the control unit 11 obtains information regarding the thickness of the third layer group 113 based on predetermined correspondence information 290 between the shape of the second interface 115 and the thickness of the third layer group 113.

[0102] Correspondence information 290 is information that associates the shape of the second interface 115 with the thickness of the third layer group 113, as shown in Table 1 below.

[0103] [Table 1]

[0104] Correspondence relationship information 290 can be obtained, for example, by measuring the shape and thickness of the rust in correspondence using an OCT device 100 or a measuring device other than an OCT device 100. Correspondence relationship information 290 is stored in the storage unit 29. Note that if the shape and thickness of the rust are measured in advance without the first layer group 111 when acquiring the correspondence relationship information 290, the information regarding the shape of the second interface 115 via the first layer group 111 will be affected by the thickness and refractive index of the first layer group 111. Therefore, if the shape and thickness of the rust are measured in advance without the first layer group 111, it is necessary to correct the measurement results of the rust shape based on the thickness and refractive index of the first layer group 111.

[0105] The thickness acquisition unit 28 acquires information regarding the thickness of the third layer group 113 by referring to the correspondence relationship information 290 based on the information regarding the shape of the second interface 115 received from the correction unit 27, and outputs it to a device other than the information processing device 1a via the output unit 24.

[0106] In this embodiment, by acquiring information regarding the thickness of the third layer group 113, it is possible to quantitatively evaluate, for example, the amount of rust generated and its change over time. The method for acquiring the thickness of the third layer group 113 by the thickness acquisition unit 28 is not limited to using the correspondence relationship information 290. For example, the shape of the second interface 115 may be used directly as the thickness of the third layer group 113, or the shape of the second interface 115 may be multiplied by a predetermined coefficient to obtain the thickness of the third layer group 113.

[0107] <Processing by information processing device 1a> Figure 16 is a flowchart showing the processing performed by the information processing device 1a. The information processing device 1a starts the processing shown in Figure 16 when it receives an optical coherence tomography signal Sg via the input unit 20. Note that the processing from steps S21 to S23 in Figure 16 is the same as the processing from steps S11 to S13 shown in Figure 11, so the explanation is omitted here.

[0108] In step S24, the information processing device 1a uses the reference signal region identification unit 25 to identify the reference signal region Rf in the optical coherence tomography signal Sg that includes the first interface 114. The reference signal region identification unit 25 then passes the information regarding the identified reference signal region Rf to the second peak position identification unit 26.

[0109] Next, in step S25, the information processing device 1a uses the second peak position identification unit 26 to identify the second peak position Ps2 with the highest signal intensity in the Z direction within the reference signal region Rf. The second peak position identification unit 26 identifies the two-dimensional distribution of the second peak position Ps2 across the entire first interface 114 along the X and Y directions. The second peak position identification unit 26 then passes the information regarding the identified two-dimensional distribution of the second peak position Ps2 to the shape acquisition unit 23.

[0110] Next, in step S26, the information processing device 1a acquires information about the three-dimensional shape of the second interface 115 by connecting the first peak positions Ps1 along the XY direction using the shape acquisition unit 23 and converting them into height data corresponding to the shape. The shape acquisition unit 23 also acquires information about the three-dimensional shape of the first interface 114 by connecting the second peak positions Ps2 along the XY direction and converting them into height data corresponding to the shape. The shape acquisition unit 23 then passes the acquired information about the three-dimensional shapes of the second interface 115 and the first interface 114 to the correction unit 27.

[0111] Next, in step S27, the information processing device 1a obtains information regarding the shape of the second interface 115 after correcting the distortion of the target signal region Tg by subtracting the shape of the first interface 114 from the shape of the second interface 115 using the correction unit 27. The correction unit 27 then passes the information regarding the corrected shape of the second interface 115 to the thickness acquisition unit 28 and the output unit 24.

[0112] Next, in step S28, the information processing device 1a, using the thickness acquisition unit 28, acquires information regarding the thickness of the third layer group 113 by referring to the correspondence relationship information 290 based on the information regarding the shape of the second interface 115. The thickness acquisition unit 28 then passes the information regarding the thickness of the third layer group 113 to the output unit 24.

[0113] Next, in step S29, the information processing device 1a outputs information regarding the three-dimensional shape of the second interface 115 and information regarding the thickness of the third layer group 113 to a device other than the information processing device 1 via the output unit 24.

[0114] As described above, the information processing device 1a can acquire information regarding the three-dimensional shape of the second interface 115 of the laminated structure 110, as well as information regarding the thickness of the third layer group 113, and output this information to a device other than the information processing device 1a.

[0115] Although preferred embodiments have been described in detail above, the embodiments of this disclosure are not limited to those described above, and various modifications and substitutions can be made to the embodiments of this disclosure without departing from the scope of the claims.

[0116] The ordinal numbers, quantities, and other figures used in the description of the embodiments of this disclosure are all illustrative to specifically illustrate the technology of this disclosure, and this disclosure is not limited to the illustrative figures. Furthermore, the connection relationships between the components are illustrative to specifically illustrate the technology of this disclosure, and are not limited to the connection relationships that realize the functions of this disclosure.

[0117] The signal processing method, information processing device, optical coherence tomography apparatus, and program disclosed herein can be suitably used for optical coherence tomography in general, regardless of the field. They are particularly suitable for use in the industrial field. Furthermore, since the signal processing method, information processing device, optical coherence tomography apparatus, and program disclosed herein can acquire the shape of interfaces with a high degree of diffusion based on optical coherence tomography signals, it is possible to accurately grasp the occurrence of metal oxides such as rust at the interface between paint and metal materials, and to contribute to activities that maintain the aesthetic appearance and strength of vehicles and structures. [Explanation of symbols]

[0118] 1, 1a Information Processing Device 2 Signal acquisition device 3 Operating device 4 Display device 11 Control Unit 12 ROM 13 RAM 14 HDD / SSD 15 DAQ device 16 External I / F 20 Input section 21 Target signal area identification unit 22. First Peak Location Identification Unit 23 Shape acquisition section 24 Output section 25 Reference signal area identification section 26. Second Peak Location Identification Unit 27 Correction section 28 Thickness acquisition section 29 Storage Unit 290 Correspondence Information 41 Metal materials 42 Paint 43 Rust 50, 60 interface 100 OCT equipment 101 Frequency scanning light source 102 Coupler 103 Circulator 104 Probe Optics 105 Collimator 106 Galvano Mirror 107 Objective lens 108 Reference Member 109 Reference plane 110 Laminated Structure 111 The first strata 112 Second Strata 113 The third group 114 1st interface 115 2nd interface 121 Galvano Mirror Driver 122 Variable Optical Attenuator 123 Differential Optical Detector Amplifier B Bus L0 light L1 1st split light L2 2nd split light P1 (First Peak) P2 (Second Peak) Ps1 First Peak Position R reflected light Rf reference signal area S1 1st signal strength distribution S2 2nd signal strength distribution Sg optical coherence tomography signal SP1, SP2, SP3 ports Tg Target signal region W1, W2 width

Claims

1. A signal processing method performed by an information processing device having a control unit, The control unit, By inputting the optical coherence tomography signal obtained by optical coherence tomography, In the optical coherence tomography signal, a target signal region is identified that corresponds only to the second interface among the first interface between a first group of layers containing one or more layers and a second group of layers containing one or more layers, and the second interface between the second group of layers and a third group of layers containing one or more layers. In the target signal region, the first peak position with the highest signal intensity in the stacking direction in which the first layer group, the second layer group, and the third layer group are stacked is identified. Based on the first peak position, information regarding the shape of the second interface is output. The laminated structure comprising the second layer group and the third layer group has a transmittance of 20% or less for light with a wavelength of 960 nm to 2000 nm. The third group of layers includes a layer consisting of rust, The signal processing method includes a second group of layers, each layer being made of paint.

2. The signal processing method according to claim 1, wherein the control unit corrects the distortion of the target signal region.

3. A signal processing method performed by an information processing device having a control unit, The control unit, By inputting the optical coherence tomography signal obtained by optical coherence tomography, In the optical coherence tomography signal, a target signal region is identified that corresponds only to the second interface among the first interface between a first group of layers containing one or more layers and a second group of layers containing one or more layers, and the second interface between the second group of layers and a third group of layers containing one or more layers. The system outputs information regarding the shape of the second interface, which is obtained based on the target signal region. In the optical coherence tomography signal, a reference signal region including the first interface is identified, In the reference signal region, the second peak position with the highest signal intensity in the stacking direction in which the first layer group, the second layer group, and the third layer group are stacked is identified. Based on the second peak position, information regarding the shape of the first interface is obtained. A signal processing method for correcting distortion in the target signal region by subtracting the shape of the first interface from the shape of the second interface.

4. The signal processing method according to claim 1, wherein the control unit outputs information regarding the thickness of the third layer group.

5. The signal processing method according to claim 4, wherein the control unit acquires information regarding the thickness of the third layer group based on predetermined correspondence information between the shape of the second interface and the thickness of the third layer group.

6. The signal processing method according to claim 3, wherein the laminated structure including the second layer group and the third layer group has a transmittance of 20% or less for light with a wavelength of 960 nm to 2000 nm.

7. The signal processing method according to claim 6, wherein the laminated structure includes a layer made of at least one of resin, metal oxide, metal, carbon, glass, ceramics, and cement.

8. The signal processing method according to claim 3, wherein the third group of layers includes a layer made of rust.

9. The signal processing method according to claim 3, wherein the second group of layers includes layers made of paint.

10. The signal processing method according to claim 1, wherein the first group of layers includes a layer of gas or liquid.

11. An information processing device having a control unit, The control unit, By inputting the optical coherence tomography signal obtained by optical coherence tomography, In the optical coherence tomography signal, a target signal region is identified that corresponds only to the second interface among the first interface between a first group of layers containing one or more layers and a second group of layers containing one or more layers, and the second interface between the second group of layers and a third group of layers containing one or more layers. The system outputs information regarding the shape of the second interface, which is obtained based on the target signal region. In the optical coherence tomography signal, a reference signal region including the first interface is identified, In the reference signal region, the second peak position with the highest signal intensity in the stacking direction in which the first layer group, the second layer group, and the third layer group are stacked is identified. Based on the second peak position, information regarding the shape of the first interface is obtained. An information processing device that corrects the distortion of the target signal region by subtracting the shape of the first interface from the shape of the second interface.

12. The information processing apparatus according to claim 11, An optical coherence tomography (OCT) apparatus comprising: a signal acquisition device for acquiring the optical coherence tomography signal of a stacked structure by optical coherence tomography.

13. The optical coherence tomography apparatus according to claim 12, wherein the signal acquisition device emits light having a wavelength of 960 nm or more and 2000 nm or less.

14. The optical coherence tomography apparatus according to claim 12 or 13, wherein the signal acquisition device emits linearly polarized, circularly polarized, or elliptically polarized light.

15. The control unit of the information processing device has By inputting the optical coherence tomography signal obtained by optical coherence tomography, Of the first interface between a first group of layers containing one or more layers and a second group of layers containing one or more layers, and the second interface between the second group of layers and a third group of layers containing one or more layers, the target signal region corresponding only to the second interface is identified. The system outputs information regarding the shape of the second interface, which is obtained based on the target signal region. In the optical coherence tomography signal, a reference signal region including the first interface is identified, In the reference signal region, the second peak position with the highest signal intensity in the stacking direction in which the first layer group, the second layer group, and the third layer group are stacked is identified. Based on the second peak position, information regarding the shape of the first interface is obtained. A program that performs a process to correct the distortion of the target signal region by subtracting the shape of the first interface from the shape of the second interface.

Images