Polarization-sensitive optical coherence tomography device

Abstract

To provide a polarization-sensitive optical interference tomography device for acquiring a tomographic image on which the polarization characteristics of a sample is reflected better.SOLUTION: The polarization-sensitive optical interference tomography device is for acquiring a signal representing polarization characteristics of a sample from reflection light of measurement light applied to the sample and interference light with reference light for reference. The device has two collimators for reference light facing each other on an optical path for the reference light, and adjusts the length of the optical path for the reference light by the collimators for reference light.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to polarization-sensitive optical coherence tomography devices. [Background technology]

[0002] Optical coherence tomography (OCT) is primarily used in the medical field for tomography of biological organs such as the eyeball.

[0003] Patent Document 1 describes a polarization OCT device in which a polarization controller is arranged in each of a measurement light side fiber, a reference light side fiber, and a detector side fiber. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-130974 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present disclosure is to provide a polarization-sensitive optical coherence tomography apparatus capable of acquiring a tomographic image that better reflects the polarization characteristics of a sample. [Means for solving the problem]

[0006] The present disclosure (1) provides a polarization-sensitive optical coherence tomography apparatus that acquires a signal representing the polarization characteristics of a sample from interference light between reflected light of measurement light irradiated onto the sample and reference light for reference, two collimators for reference light disposed opposite to each other on an optical path of the reference light; The polarization-sensitive optical coherence tomography apparatus adjusts the optical path length of the reference light by using the reference light collimator.

[0007] The present disclosure (2) is a polarization-sensitive optical coherence tomography apparatus according to the present disclosure (1), which includes a polarization control element on the optical path of the measurement light irradiated onto the sample, for adjusting the polarization state of the measurement light.

[0008] The present disclosure (3) is a polarization-sensitive optical coherence tomography device according to the present disclosure (1) or (2), which includes a coupler (1) that splits light from a light source into measurement light that is irradiated onto the sample and the reference light, and the intensity ratio between the measurement light and the reference light is 60:40 to 95:5.

[0009] The present disclosure (4) is a polarization-sensitive optical coherence tomography device in any combination with any of the present disclosures (1) to (3), which includes a polarizing beam splitter that splits the interference light into a vertically polarized component and a horizontally polarized component, a vertically polarized component-sensitive detector that detects the vertically polarized component, and a horizontally polarized component-sensitive detector that detects the horizontally polarized component.

[0010] The present disclosure (5) is a polarization-sensitive optical coherence tomography device that uses light having a central wavelength in the range of 950 to 1400 nm as light from a light source, and is any combination with any of the present disclosures (1) to (4).

[0011] The present disclosure (6) is a polarization-sensitive optical coherence tomography device that includes a wavelength swept light source, in which the wavelength sweep width of light from the wavelength swept light source is 100 to 200 nm and the repetitive scanning frequency is 30 to 120 kHz, and that can be arbitrarily combined with any of the present disclosures (1) to (5).

[0012] The present disclosure (7) is a polarization-sensitive optical coherence tomography device that can be combined with any of the present disclosures (1) to (6) and is configured so that a user can perform tomography while carrying the part that includes the objective lens.

[0013] The present disclosure (8) is a polarization-sensitive optical coherence tomography device that can be arbitrarily combined with any of the present disclosures (1) to (7) and is configured to be capable of acquiring the vertically polarized component and the horizontally polarized component of the interference light in accordance with the polarization axis of the sample.

[0014] The present disclosure (9) is a polarization-sensitive optical coherence tomography apparatus that is provided with a variable focus lens with a variable focal length, and is optionally combined with any of the present disclosures (1) to (8).

[0015] The present disclosure (10) provides a polarization-sensitive optical coherence tomography apparatus, comprising: an optical path length adjustment module having a collimator for the reference light on an optical path of the reference light; a coupler (2) that combines the reflected light of the measurement light and the reference light; a measurement light collimator that converts the measurement light into parallel light; a scanning mirror that scans the measurement light irradiated onto the sample, No polarization control element is provided on the optical path between the coupler (1) and the reference light collimator, The two reference light collimators are disposed facing each other so as to be positioned substantially in a straight line, the reference beam collimator has a variable angle and / or variable position; the optical path length adjustment module includes a holding member that holds each of the reference light collimators; The holding member is a polarization-sensitive optical coherence tomography apparatus in any combination with any of the present disclosures (3) to (9), in which the angle and / or position of the reference beam collimator can be adjusted.

[0016] The present disclosure (11) is a polarization-sensitive optical coherence tomography apparatus for industrial use, which can be arbitrarily combined with any of the present disclosures (1) to (10). [Effects of the Invention]

[0017] According to the present disclosure, it is possible to provide a polarization-sensitive optical coherence tomography apparatus capable of acquiring a tomographic image that better reflects the polarization characteristics of a sample. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a schematic diagram illustrating an example of an OCT device according to the present disclosure. [Figure 2] FIG. 2 is a schematic diagram illustrating an example of an optical path length adjusting module. [Figure 3] FIG. 10 is a schematic diagram showing another example of the OCT device of the present disclosure. [Figure 4] FIG. 1 is a diagram showing an OCT image obtained in Example 1. [Figure 5] FIG. 10 is a diagram showing an OCT image obtained in Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0019] The present disclosure will be specifically described below.

[0020] The present disclosure relates to a polarization-sensitive optical coherence tomography (polarization-sensitive OCT) device that acquires a signal representing the polarization characteristics of a sample from the interference light between the reflected light of measurement light irradiated onto the sample and a reference light for reference, and that has two reference light collimators arranged opposite each other on the optical path of the reference light, and that adjusts the optical path length of the reference light using the reference light collimators (hereinafter also referred to as the OCT device of the present disclosure).

[0021] The OCT device disclosed herein includes two collimators for reference light arranged opposite each other on the optical path of the reference light. The collimators adjust the optical path length of the reference light, making it easy to accurately match the optical path lengths of the measurement light and the reference light. Even if the optical path length of the measurement light changes depending on the size and shape of the sample or the imaging environment, the optical path lengths of the measurement light and the reference light can be easily matched by adjusting the optical path length of the reference light using the collimators to match these changes. As a result, it becomes possible to acquire a tomographic image that better reflects the polarization characteristics of the sample.

[0022] The collimators for the reference light are arranged opposite each other on the optical path of the reference light, and it is preferable that the two collimators are arranged opposite each other so that they are positioned approximately in a straight line. It is also preferable that the collimators are arranged opposite each other so that light emitted from one (upstream) collimator is incident on the other (downstream) collimator. It is also preferable that the downstream collimator is used in reverse mode (reverse input).

[0023] The reference beam collimator is preferably variable in angle and / or position, more preferably variable in angle. The two reference beam collimators are preferably capable of changing their angles and / or positions independently of each other. Furthermore, it is preferable that no optical fiber is disposed between the collimators (on the opposing sides) so that the optical path length can be changed by operating the collimators. With the above configuration, the optical path length between the reference light collimators can be easily adjusted, and the optical path length of the reference light can be easily adjusted.

[0024] The OCT device of the present disclosure preferably includes an optical path length adjustment module having the above-described collimator for reference light on the optical path of the reference light. The optical path length adjustment module may have a collimator for reference light, but preferably includes, for example, holding members for holding the upstream and downstream collimators, respectively. The holding members are preferably capable of adjusting the angle and / or position of the collimators, more preferably capable of adjusting the angle, and even more preferably capable of adjusting the angle in two axes (X and Y). Each holding member may be fixed to the housing of the OCT device, or may be connected to each other by a connecting member such as a rod, like an optical cage system. The optical path length adjustment module may further include a connection member for connecting an optical fiber to the optical path length adjustment module. An example of such an optical path length adjusting module is shown in FIG. 2, which will be described later, but is not limited to this.

[0025] The measurement light and the reference light are generated from light from a light source. The OCT device of the present disclosure may include a light source. The light source may be a low-coherence light source, and is preferably a wavelength-swept light source (frequency-swept light source) that changes and scans the frequency (wavelength) over time. The wavelength swept light source may be a wavelength swept laser using a wavelength swept filter (driven by a polygon mirror, driven by a galvanometer mirror, etc.), an FDML laser, a MEMS wavelength swept light source (MEMS VCSEL, external cavity MEMS Fabry-Perot laser, etc.), an SGDBR laser, etc.

[0026] When a wavelength swept light source is used, the wavelength sweep width of the light is preferably 100 to 200 nm, more preferably 120 nm or more, even more preferably 130 nm or more, and more preferably 180 nm or less, even more preferably 150 nm or less. The repetitive scanning frequency is preferably 30 to 120 kHz, more preferably 40 kHz or higher, more preferably 100 kHz or lower, even more preferably 80 kHz or lower, and even more preferably 60 kHz or lower. With the above configuration, the resolution in the depth direction (depth direction) can be improved.

[0027] Examples of light from the light source include visible light and infrared light, with near-infrared light (NIR) being preferred. Light from the light source preferably has a central wavelength in the range of 800 to 2000 nm. The central wavelength is more preferably 950 nm or more, and more preferably 1400 nm or less. Among these, light having a central wavelength of 1060±50 nm or 1310±50 nm is preferred, and light having a central wavelength of 1060±50 nm is more preferred, in terms of improving the resolution in the depth direction (depth direction).

[0028] The OCT device of the present disclosure preferably includes a coupler (1) that splits light from a light source into measurement light that irradiates a sample and reference light for reference. The intensity ratio of the measurement light to the reference light generated by the coupler (1) is preferably 60:40 to 95:5, more preferably 70:30 or more, even more preferably 80:20 or more, even more preferably 85:15 or more, and more preferably 92:8 or less. By setting the intensity ratio within the above range, the irradiation intensity of the measurement light onto the sample can be increased, and the sensitivity of the OCT can be improved.

[0029] The OCT device of the present disclosure may include an objective lens for irradiating the sample with measurement light. The objective lens is not limited as long as it is a lens that can focus the measurement light on the sample, but is preferably a short-focus lens in terms of improving lateral resolution. Furthermore, a variable-focus lens with a variable focal length is also preferable, since the focal point in the depth direction can be freely manipulated and high-resolution tomographic images can be obtained.

[0030] The OCT device of the present disclosure preferably includes a polarization control element (hereinafter also referred to as polarization control element (1)) on the optical path of the measurement light irradiated onto the sample, the polarization control element (1) adjusting the polarization state of the measurement light. The polarization control element (1) is preferably provided on the optical path between the coupler (1) and the objective lens. Depending on the size and shape of the sample and the imaging environment, it may be necessary to move the probe (the part with the objective lens) to various angles to capture images. If the bending of the optical fiber that transmits the measurement light changes accordingly, the polarization state of the measurement light may change. By providing the polarization control element (1) together with the above-mentioned collimator for reference light, it is possible to more accurately compensate for changes in the polarization state of the measurement light caused by bending of the optical fiber.

[0031] The polarization state can be adjusted, for example, by observing the OCT signal. By observing the polarized OCT signals in two orthogonal polarization directions and adjusting them so that the shading of the polarized stripes in the image is inverted and the contrast between the shading of each stripe pattern is maximized, the optimal polarization state for polarization-sensitive OCT can be achieved.

[0032] The polarization control element (1) can also be provided on the outside of the housing of the OCT device. This configuration makes it easy to adjust the polarization state to the optimum state for the sample being imaged, especially when imaging while carrying a probe.

[0033] A polarization control element can be provided on the optical path between the coupler (1) and the reference light collimator. However, in the OCT device of the present disclosure, the optical path length can be adjusted by the reference light collimator, so there is no need to provide a polarization control element at the above location.

[0034] The measurement light irradiated onto the sample is reflected by the sample to become reflected light (sample light), which is then combined with the reference light that has passed through the reference light collimator to become interference light. In the OCT device of the present disclosure, the reference light collimator also functions as a reference surface, so there is no need to provide a separate reference surface such as a reference mirror.

[0035] The OCT device of the present disclosure preferably includes a coupler (2) that combines the reflected measurement light and the reference light. In this case, a collimator for the reference light is preferably provided on the optical path of the reference light between the coupler (1) and the coupler (2). The reflected light of the measurement light to be combined may be light that has passed through the coupler (1). The interference light may be split into two by a coupler (2) and then emitted.

[0036] A polarization control element (also referred to as polarization control element (2)) may be provided on the optical path between the reference light collimator and coupler (2) and on the optical path of the measurement light between coupler (1) and coupler (2).

[0037] The OCT device of the present disclosure acquires a signal representing the polarization characteristics of the sample from the interference light. The OCT device of the present disclosure preferably includes a detector that detects the interference signal based on the interference light. The detector is preferably a differential photodetector and may have a function to amplify the signal. Alternatively, a separate amplifier may be provided.

[0038] The OCT device of the present disclosure preferably includes a polarizing beam splitter that splits the interference light into a vertically polarized component and a horizontally polarized component, a vertical polarization-sensitive detector that detects the vertically polarized component, and a horizontal polarization-sensitive detector that detects the horizontally polarized component. This configuration allows us to obtain information from both vertically and horizontally polarized components, enabling us to obtain tomographic images that better reflect the polarization characteristics of the sample.

[0039] A polarizing beam splitter is preferably provided in the optical path between the coupler (2) and the vertical polarization-sensitive detector or the horizontal polarization-sensitive detector. Moreover, it is preferable that the polarizing beam splitter is provided on each optical path of the interference light split into two by the coupler (2).

[0040] A polarization control element (also referred to as polarization control element (3)) may be provided on the optical path between the coupler (2) and the polarizing beam splitter.

[0041] The interferometer that can be used in the OCT device of the present disclosure is not particularly limited, and examples thereof include a Michelson interferometer and a Mach-Zehnder interferometer.

[0042] Types of OCT that can be used in the OCT device of the present disclosure include time domain OCT (TD-OCT), Fourier domain OCT (FD-OCT), etc. Examples of FD-OCT include spectral domain OCT (SD-OCT) and swept source OCT (SS-OCT). Of these, SS-OCT is preferred due to its high sensitivity and large measurable depth.

[0043] The OCT device of the present disclosure preferably further includes a measurement light collimator that converts the measurement light into parallel light. The measurement light collimator is preferably provided on the optical path between the light source and the objective lens, more preferably on the optical path between the coupler (1) and the objective lens, and even more preferably on the optical path between the polarization control element (1) and the objective lens. As the measurement light collimator, it is preferable to use a collimating lens with a large diameter in order to improve the lateral resolution. The diameter of the measurement light collimator is, for example, preferably 2 mm or more, more preferably 4 mm or more, and from the viewpoint of portability of the probe, preferably 12 mm or less.

[0044] The OCT device of the present disclosure preferably further includes a scanning mirror that scans the measurement light irradiated onto the sample. The scanning mirror is preferably provided on the optical path between the light source and the objective lens, more preferably on the optical path between the coupler (1) and the objective lens, and even more preferably on the optical path between the measurement light collimator and the objective lens.

[0045] Examples of the scanning mirror include a galvanometer mirror, a polygon mirror, an MEMS mirror, etc. Among these, a galvanometer mirror is preferred, a uniaxial or biaxial galvanometer mirror is more preferred, and a biaxial galvanometer mirror is even more preferred.

[0046] The OCT device of the present disclosure preferably further includes a driving device for driving the scanning mirror.

[0047] The OCT device of the present disclosure preferably further includes a data acquisition (DAQ) device that collects interference signals from the measurement light and the reference light. The DAQ device preferably includes an A / D converter. The DAQ device preferably converts the collected interference signals into digital data.

[0048] The OCT device of the present disclosure preferably further includes a calculation device that generates an optical coherence tomographic image based on an interference signal between the measurement light and the reference light. The calculation device generates the optical coherence tomographic image by converting the interference signal into an image according to characteristics such as intensity.

[0049] The OCT device of the present disclosure preferably further includes a display device for displaying the obtained optical coherence tomographic image. The display device may be a stationary or portable type, but a portable type is preferable because it allows the image to be confirmed at the imaging site. The connection to the computing device may be wired or wireless. The display device may be one or more.

[0050] In the OCT device of the present disclosure, devices or components through which light enters or exits may be connected by optical fibers. A single-mode fiber (SMF) is preferably used as the optical fiber. The optical fiber entering the polarizing beam splitter (the optical fiber forming the optical path between the coupler (2) and the polarizing beam splitter) may be a polarization-maintaining fiber (PFM).

[0051] An example of the OCT device of the present disclosure is shown in FIG. 1, but the OCT device of the present disclosure is not limited to this. In the OCT device 100 shown in Fig. 1, a wavelength swept light source 101 outputs light used for OCT. The wavelength swept light source 101 outputs a trigger signal at the start of each frequency scan. The light is detected by a Mach-Zehnder interferometer, and a K clock signal is output for sampling at equal frequency intervals. Light output from a wavelength swept light source 101 passes through an optical fiber 102 and is split by a coupler 103 into measurement light to be irradiated onto a sample and reference light for reference at an intensity ratio of 90:10. The measurement light is transmitted to a probe 106 through an optical fiber 104 having a length of several meters. The optical fiber 104 is provided with a polarization control element 105 that compensates for changes in the polarization state of the measurement light. In the probe 106, the measurement light is converted into parallel light by a collimator 107, and then reflected by a galvanometer mirror 108 to enter an objective lens 109. The galvanometer mirror 108 is driven by a galvanometer mirror driver (not shown) to scan the parallel light in the X and Y directions perpendicular to the optical axis. The parallel light incident on the objective lens 109 is focused on a sample 110 to be imaged, reflected on the sample surface, and returns to the coupler 103 via the same optical path as the reflected light (sample light), emitted to an optical fiber 111, passes through a polarization control element 112, and enters the coupler 118. On the other hand, the reference light emitted from the coupler 103 passes through the optical fiber 113 and the collimator 115 provided in the upstream optical path length adjustment module 114 to become parallel light. The parallel light passes through the reverse mode collimator 115 provided in the downstream optical path length adjustment module 114 and is guided to the optical fiber 116. The upstream and downstream optical path length adjustment modules 114 each include a collimator 115, and the two collimators 115 are arranged to face each other. A schematic diagram of the optical path length adjustment module 114 is shown in FIG. 2. The optical path length adjustment module 114 includes an angle adjustment holder 114a that holds the collimator 115 so that the angle can be adjusted in two axes (X and Y), a fixing member 114b that fixes the angle adjustment holder 114a to the housing, and a fiber connector 114c that connects the optical fiber 113 or 116. The optical path length of the reference light can be adjusted by adjusting the angle of the collimator 115 by moving the angle adjustment holder 114a. In Figure 2, the angle adjustment holder 114a is fixed to the housing by the fixing member 114b, but the optical cage system may also be constructed by connecting the upstream and downstream angle adjustment holders 114a with multiple steel rods without using the fixing member 114b. The reference light emitted from the downstream optical path length adjusting module 114 passes through an optical fiber 116, passes through a polarization control element 117, and enters a coupler 118, where it is combined with the sample light to become interference light. The interference light is split into two by coupler 118, one of which passes through optical fiber 119, passes through polarization control element 120, and enters polarization beam splitter 121, and the other passes through optical fiber 124, passes through polarization control element 125, and enters polarization beam splitter 126. The interference light incident on the polarizing beam splitters 121 and 126 is split into a horizontally polarized component and a vertically polarized component, and the horizontally polarized component passes through optical fibers 122 and 127 and enters a horizontal polarization-sensitive detector 129, while the vertically polarized component passes through optical fibers 123 and 128 and enters a vertical polarization-sensitive detector 130. The horizontal polarization-sensitive detector 129 and the vertical polarization-sensitive detector 130 detect interference signals based on the horizontally polarized component and the vertically polarized component of the interference light, respectively. The detected interference signal is collected by a DAQ device (A / D converter) (not shown) provided in a control unit (not shown) and converted into digital data. The collection of the interference signal is started by a trigger signal emitted by the wavelength swept light source 101 and is performed in synchronization with the K clock signal. The arithmetic unit included in the control unit generates an optical coherence tomographic image of the sample 110 based on the interference signal converted by the DAQ unit, and displays it on a mobile display (not shown).

[0052] The OCT device of the present disclosure is preferably configured so that the user can carry the part containing the objective lens while performing tomographic imaging. By making the part containing the objective lens portable in this way, imaging can be performed from various positions and angles depending on the size and shape of the sample. In addition, it is possible to acquire vertically polarized and horizontally polarized components of interference light in accordance with the polarization axis of the sample. If the part containing the objective lens is made portable, the optical path length of the measurement light is likely to change during imaging. However, the OCT device disclosed herein can adjust the optical path length of the reference light using a reference light collimator, thereby enabling the acquisition of tomographic images that better reflect the polarization characteristics of the sample.

[0053] The part including the objective lens is, for example, a probe of an OCT device, and preferably includes a measuring light collimator, a scanning mirror, and the like in addition to the objective lens.

[0054] The OCT device of the present disclosure is preferably configured so that a user can hold the part with the objective lens in one hand and perform tomography, and more preferably so that a user can hold the part with the objective lens in one hand and perform tomography.

[0055] The OCT device of the present disclosure may also include a part that can be carried by the user during tomography, in addition to the part that includes the objective lens. Such a part may include, for example, a display device.

[0056] In the OCT device disclosed herein, it is preferable that the portion equipped with the portable objective lens and the non-portable portion are connected via an optical fiber, and the measurement light and its reflected light (sample light) are transmitted through the optical fiber. In this embodiment, even if the imaging target is located far from the non-portable portion, by adjusting the length of the optical fiber, the portion equipped with the objective lens can be positioned near the imaging target to perform tomographic imaging. Furthermore, because it is a wired type using an optical fiber, high-resolution OCT measurement can be performed even on imaging targets located far from the non-portable portion.

[0057] The length of the optical fiber is not particularly limited and can be determined depending on the location of the subject to be photographed, but may be, for example, 0.5 m or more, preferably 1 m or more, or 5 m or less, preferably 3 m or less. By keeping the value within the above range, it becomes easy to carry the part with the objective lens and perform tomography while operating the equipment (polarization control element, etc.) arranged in the OCT device main body (housing).

[0058] The non-portable part is, for example, the OCT device main body (housing), which preferably includes a light source, a polarization control element, a collimator for reference light, a detector, a DAQ device, a computing device, and the like.

[0059] If there is a portable part other than the part having the objective lens, the connection between that part and the part having the objective lens or the non-portable part is not necessarily limited to a connection by optical fiber, but may also be a connection by, for example, an electric wire.

[0060] The OCT device of the present disclosure is preferably configured to acquire vertically and horizontally polarized components of interference light aligned with the polarization axis of the sample, thereby enabling acquisition of a tomographic image that better reflects the polarization characteristics of the sample. The above configuration can be realized, for example, by making the part (probe) equipped with the objective lens portable.

[0061] Another example of the OCT device of the present disclosure (an example in which the part including the objective lens is made portable) is shown in FIG. 3, but the OCT device of the present disclosure is not limited to this. 3, a user 201 carries a probe 202 of the OCT device in one hand. The probe 202 is connected to a housing 204 of the OCT device via an optical fiber 203. The housing 204 houses a light source, a polarization control element, a collimator for reference light, a galvanometer mirror driver, a detector, a DAQ device, a computing device, etc. In addition, a polarization control element 205 for measurement light is installed outside the housing 204, and can be operated by the user 201 during tomography.

[0062] The OCT device of the present disclosure can be suitably used for polarization-sensitive optical coherence tomography in general, regardless of the field, and particularly in fields where a wide variety of samples are imaged and the optical path length of the measurement light is likely to change depending on the sample and the imaging environment, such as the physical and chemical fields and industrial fields. The OCT device of the present disclosure is preferably for physicochemical or industrial use, and more preferably for industrial use.

[0063] Although the embodiments have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the claims. [Example]

[0064] The present disclosure will now be described in more detail with reference to examples, but the present disclosure is not limited to these examples.

[0065] Example 1 Using a polarization-sensitive OCT device with the configuration shown in Figure 1, OCT images were taken of the side of the lid of a glue stick (Kieiro Pit N, PT-NC) manufactured by Tombow Pencil Co., Ltd. An Excelitas high-speed wavelength swept light source (center wavelength: 1060 nm, sweep width: 140 nm, repetitive scanning frequency: 50 kHz) was used as the OCT light source, and two sets of Thorlabs F280APC-1064 reference collimators were connected to a collimator adapter (Thorlabs AD1109) and held on a kinematic mount (Thorlabs KC05-T / M) and arranged opposite each other. Using the OCT imaging described above, sample images based on light waves oscillating in the horizontal direction (P-polarized waves) and sample images based on light waves oscillating in the vertical direction (S-polarized waves) were obtained. A Gaussian filter was applied to all sample images to remove noise. Background information (BG images) was removed from each of the sample images of P-polarized waves and S-polarized waves, and P-polarized wave images and S-polarized wave images were obtained. All pixels of the obtained P-polarized wave image and S-polarized wave image were processed using the following formula to generate a phase contrast image.

number

[0066] Example 2 OCT imaging of a fine pattern NBS 1963A resolution test target (R2L2S1P1 manufactured by Thorlabs) was performed using the same polarization-sensitive OCT device as in Example 1. The obtained OCT image is shown in FIG. It was possible to clearly distinguish down to a few microns, and high lateral resolution was achieved. [Explanation of symbols]

[0067] 100:OCT device 101: Wavelength swept light source 102, 104, 111, 113, 116, 119, 122, 123, 124, 127, 128: Optical fiber 103, 118: Coupler 105, 112, 117, 120, 125: Polarization control elements 106: Probe 107: Collimator 108: Galvanometer mirror 109: Objective lens 110: Sample 114: Optical path length adjustment module 114a: Angle adjustment holder 114b: Fixing member 114c: Fiber connector 115: Collimator 121, 126: Polarizing beam splitter 129: Horizontal polarization sensitive detector 130: Vertical polarization sensitive detector 201: User 202: Probe 203: Optical fiber 204: Cabinet 205: Polarization control element

Claims

1. A polarization-sensitive optical coherence tomography apparatus that acquires a signal representing a polarization characteristic of a sample from interference light between reflected light of measurement light irradiated onto the sample and reference light for reference, two collimators for reference light disposed opposite to each other on an optical path of the reference light; a coupler (1) that splits light from a light source into measurement light that irradiates the sample and the reference light; adjusting the optical path length of the reference light by the reference light collimator; the reference light collimator has a variable angle; A polarization-sensitive optical coherence tomography apparatus, wherein the intensity ratio of the measurement light to the reference light is 60:40 to 95:

5.

2. 2. The polarization-sensitive optical coherence tomography apparatus according to claim 1, further comprising a polarization control element for adjusting the polarization state of the measurement light, which is disposed on an optical path of the measurement light irradiated onto the sample.

3. 3. The polarization-sensitive optical coherence tomography device according to claim 1, further comprising a polarizing beam splitter that splits the interference light into a vertically polarized component and a horizontally polarized component, a vertical polarization-sensitive detector that detects the vertically polarized component, and a horizontal polarization-sensitive detector that detects the horizontally polarized component.

4. 3. The polarization-sensitive optical coherence tomography apparatus according to claim 1, wherein light having a central wavelength in the range of 950 to 1400 nm is used as light from the light source.

5. 3. The polarization-sensitive optical coherence tomography apparatus according to claim 1, further comprising a wavelength swept light source, wherein the wavelength sweep width of light from the wavelength swept light source is 100 to 200 nm, and the repetitive scanning frequency is 30 to 120 kHz.

6. 3. The polarization-sensitive optical coherence tomography apparatus according to claim 1, wherein the apparatus is configured so that a user can carry the part including the objective lens while performing tomography.

7. 3. The polarization-sensitive optical coherence tomography apparatus according to claim 1, wherein the apparatus is configured to be capable of acquiring vertically polarized components and horizontally polarized components of the interference light in accordance with the polarization axis of the sample.

8. 3. The polarization-sensitive optical coherence tomography apparatus according to claim 1, further comprising a variable-focus lens whose focal length is variable.

9. The polarization-sensitive optical coherence tomography apparatus includes an optical path length adjustment module having a collimator for the reference light on an optical path of the reference light; a coupler (2) that combines the reflected light of the measurement light and the reference light; a measurement light collimator that converts the measurement light into parallel light; a scanning mirror that scans the measurement light irradiated onto the sample, No polarization control element is provided on the optical path between the coupler (1) and the reference light collimator, The two reference light collimators are disposed opposite to each other so as to be positioned substantially in a straight line, the reference light collimator is further variable in position; the optical path length adjustment module includes a holding member that holds each of the reference light collimators; 3. The polarization-sensitive optical coherence tomography apparatus according to claim 1, wherein the holding member is capable of adjusting the angle and / or position of the reference beam collimator.

10. 3. The polarization-sensitive optical coherence tomography apparatus according to claim 1, which is for industrial use.

Images