Polarization-sensitive optical coherence tomography device

Abstract

The purpose of this disclosure is to provide a polarization-sensitive optical coherence tomography apparatus capable of obtaining tomographic images that better reflect the polarization characteristics of a sample. This disclosure is a polarization-sensitive optical coherence tomography apparatus that obtains a signal representing the polarization characteristics of the sample from the interference light between the reflected light of a measurement light illuminating the sample and a reference light used for reference. The apparatus includes two collimators for the reference light arranged opposite each other on the optical path of the reference light, and the optical path length of the reference light is adjusted using these collimators.

Description

Technical Field

[0001] This disclosure relates to a polarization-sensitive optical coherence tomography apparatus. Background Technology

[0002] Optical coherence tomography (OCT) is mainly used in the medical field for tomographic imaging of biological organs such as the eye.

[0003] Patent document 1 describes a polarization OCT device in which polarization controllers are respectively configured on the measuring optical fiber, the reference optical fiber, and the detector optical fiber.

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2015-130974 Summary of the Invention

[0007] The problem that the invention aims to solve

[0008] The purpose of this disclosure is to provide a polarization-sensitive optical coherence tomography apparatus capable of acquiring tomographic images that better reflect the polarization characteristics of a sample.

[0009] Methods for solving problems

[0010] This disclosure (1) is a polarization-sensitive optical coherence tomography apparatus that obtains a signal representing the polarization characteristics of the sample from the interference light of the reflected light of the measurement light irradiating the sample and the reference light used for reference, wherein, The polarization-sensitive optical coherence tomography apparatus includes two collimators for the reference light arranged opposite each other in the optical path of the reference light. The optical path length of the reference light is adjusted using a collimator.

[0011] This disclosure (2) is the polarization-sensitive optical coherence tomography apparatus described in this disclosure (1), wherein a polarization control element for adjusting the polarization state of the measurement light is provided in the optical path of the measurement light irradiating the sample.

[0012] This disclosure (3) is a polarization-sensitive optical coherence tomography apparatus as described in disclosure (1) or (2), wherein the polarization-sensitive optical coherence tomography apparatus includes a coupler (1) that splits light from a light source into a measurement light and a reference light that irradiates the sample, wherein the intensity ratio of the measurement light to the reference light is 60:40 to 95:5.

[0013] This disclosure (4) is a polarization-sensitive optical coherence tomography apparatus in any combination with any one of the present disclosures (1) to (3), wherein the polarization-sensitive optical coherence tomography apparatus comprises: a polarization beam splitter that splits the interference light into a vertical polarization component and a horizontal polarization component; a vertical polarization-sensitive detector that detects the vertical polarization component; and a horizontal polarization-sensitive detector that detects the horizontal polarization component.

[0014] This disclosure (5) is a polarization-sensitive optical coherence tomography apparatus that is any combination with any one of the disclosures (1) to (4), wherein the light from the light source is light having a center wavelength in the range of 950 nm to 1400 nm.

[0015] This disclosure (6) is a polarization-sensitive optical coherence tomography apparatus in any combination with any one of the present disclosures (1) to (5), wherein the polarization-sensitive optical coherence tomography apparatus has a wavelength scanning light source, the wavelength scanning width of the light from the wavelength scanning light source is 100nm to 200nm, and the repetition scanning frequency is 30kHz to 120kHz.

[0016] This disclosure (7) is a polarization-sensitive optical coherence tomography apparatus in any combination with any one of the present disclosures (1) to (6), wherein the polarization-sensitive optical coherence tomography apparatus is configured such that a user can carry a part equipped with an objective lens while performing tomography.

[0017] This disclosure (8) is a polarization-sensitive optical coherence tomography apparatus in any combination with any one of the present disclosures (1) to (7), wherein the polarization-sensitive optical coherence tomography apparatus is configured to obtain the vertical polarization component and the horizontal polarization component of the interference light according to the polarization axis of the sample.

[0018] This disclosure (9) is a polarization-sensitive optical coherence tomography apparatus in any combination with any one of the present disclosures (1) to (8), wherein the polarization-sensitive optical coherence tomography apparatus has a variable focal length lens.

[0019] This disclosure (10) is a polarization-sensitive optical coherence tomography apparatus that is in any combination with any of the present disclosures (3) to (9), wherein, The polarization-sensitive optical coherence tomography device includes: An optical path length adjustment module, which has a collimator for the reference light in the optical path of the reference light; Coupler (2) that combines the reflected light of the measurement light with the reference light; A collimator for measuring light, which converts the measuring light into parallel light; and A scanning mirror that scans the measurement light illuminating the sample. There is no polarization control element in the optical path between the coupler (1) and the collimator for the reference light. The two reference light collimators are arranged opposite each other in a manner that is approximately in a straight line. The angle and / or position of the collimator used for the reference light are variable. The optical path length adjustment module includes holding components for holding the collimator used for the reference light. The holding component can adjust the angle and / or position of the collimator for the reference light.

[0020] This disclosure (11) is a polarization-sensitive optical coherence tomography apparatus in any combination with any one of the present disclosures (1) to (10), wherein the polarization-sensitive optical coherence tomography apparatus is for industrial use.

[0021] According to this disclosure, a polarization-sensitive optical coherence tomography apparatus can be provided that can acquire tomographic images that better reflect the polarization characteristics of the sample. Attached Figure Description

[0022] Figure 1 This is a schematic diagram illustrating an example of the OCT device disclosed herein.

[0023] Figure 2 This is a schematic diagram illustrating an example of an optical path length adjustment module.

[0024] Figure 3 This is a schematic diagram illustrating another example of the OCT device of this disclosure.

[0025] Figure 4 This is a diagram showing the OCT image obtained in Example 1.

[0026] Figure 5 This is a diagram showing the OCT image obtained in Example 2. Detailed Implementation

[0027] The following details this disclosure.

[0028] This disclosure relates to a polarization-sensitive optical coherence tomography (polarization-sensitive OCT) apparatus (hereinafter also referred to as the OCT apparatus of this disclosure), which obtains a signal representing the polarization characteristics of the sample from the interference light of the reflected light of the measurement light irradiating the sample and the reference light for reference. The polarization-sensitive OCT apparatus includes two collimators for reference light arranged opposite each other in the optical path of the reference light, and the optical path length of the reference light is adjusted by the collimators for reference light.

[0029] Because the OCT apparatus of this disclosure has two collimators for the reference light arranged opposite each other on the optical path of the reference light, and the optical path length of the reference light is adjusted by these collimators, it is easy to accurately match the optical path lengths of the measurement light and the reference light. Even when the optical path length of the measurement light may vary depending on the size, shape, and photographic environment of the sample, it is easy to match the optical path lengths of the measurement light and the reference light by adjusting the optical path length of the reference light using the collimators according to this variation. As a result, tomographic images that better reflect the polarization characteristics of the sample can be obtained.

[0030] Preferably, the collimators for the reference light are arranged opposite each other in the optical path of the reference light, with the two collimators arranged opposite each other in a substantially straight line. Furthermore, it is preferable that the collimators are arranged such that light emitted from one (upstream) collimator is incident on the other (downstream) collimator. Additionally, the downstream collimator is preferably used in reverse mode (inverse input).

[0031] Regarding the collimator for the reference light, it is preferable that the angle and / or position is variable, more preferably that the angle is variable. Preferably, the two collimators for the reference light can change their angle and / or position independently of each other. Furthermore, it is preferable that no optical fiber is arranged between the collimators (on the opposite side) so that the optical path length can be changed by the operation of the collimators.

[0032] With the configuration described above, the optical path length between the collimators for the reference light can be easily adjusted.

[0033] The OCT device disclosed herein preferably includes an optical path length adjustment module having the aforementioned collimator for the reference light in the optical path of the reference light.

[0034] The aforementioned optical path length adjustment module only needs to have a collimator for reference light, but it is preferable to have, for example, a holding member for holding the collimators on the upstream and downstream sides respectively. The aforementioned holding member is preferably capable of adjusting the angle and / or position of the collimator, more preferably capable of adjusting the angle, and even more preferably capable of performing 2-axis (XY) angle adjustment.

[0035] Each holding component can be fixed to the frame of the OCT device, or it can be connected to each other via connecting components such as rods, similar to an optical cage system.

[0036] The optical path length adjustment module may also include a connecting component that connects the optical fiber to the optical path length adjustment module.

[0037] As such an optical path length adjustment module, examples can be shown later. Figure 2 The modules shown are not limited to these.

[0038] The measuring light and reference light are generated from light from a light source. The OCT device disclosed herein may also have a light source.

[0039] The aforementioned light source can be a low-coherence light source, preferably a wavelength scanning light source (frequency scanning light source) that scans the frequency (wavelength) over time.

[0040] As the aforementioned wavelength scanning light source, wavelength scanning lasers, FDML lasers, MEMS wavelength scanning light sources (MEMS VCSEL, external resonator type MEMS Fabry-Perot laser, etc.) that utilize wavelength scanning filters (driven by multifaceted mirrors, driven by galvanometer mirrors, etc.) and SGDBR lasers can be used.

[0041] When using a wavelength scanning light source, the wavelength scanning width of the light is preferably 100 to 200 nm, more preferably 120 nm or more, even more preferably 130 nm or more, and even more preferably 180 nm or less, and even more preferably 150 nm or less.

[0042] Furthermore, the repetition frequency is preferably 30 to 120 kHz, more preferably 40 kHz or higher, even more preferably 100 kHz or lower, further preferably 80 kHz or lower, and even more preferably 60 kHz or lower.

[0043] The above structure can improve the resolution in the depth direction.

[0044] Light from a light source can include visible light and infrared light, with near-infrared (NIR) light being the most preferred. Light with a center wavelength in the range of 800–2000 nm is preferred. The center wavelength range is more preferably 950 nm or higher, and even more preferably 1400 nm or lower.

[0045] From the viewpoint of improving the resolution in the depth direction, light with a center wavelength of 1060±50nm or 1310±50nm is preferred, and light with a center wavelength of 1060±50nm is even more preferred.

[0046] The OCT apparatus disclosed herein preferably includes a coupler (1) that splits light from a light source into a measurement light that illuminates the sample and a reference light for reference.

[0047] 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 even more preferably 92:8 or less.

[0048] By setting the intensity ratio within the above range, the intensity of the measurement light irradiating the sample can be increased, thereby improving the sensitivity of OCT.

[0049] The OCT apparatus disclosed herein may include an objective lens for illuminating the measurement light onto the sample. The objective lens is not limited to any lens capable of focusing the measurement light onto the sample; however, a short focal length lens is preferred from the perspective of improving lateral resolution.

[0050] Furthermore, a variable focal length lens is preferred in terms of being able to freely manipulate the focal point in the depth direction and obtain high-resolution tomographic images.

[0051] The OCT apparatus disclosed herein preferably includes a polarization control element (hereinafter also referred to as polarization control element (1)) in the optical path of the measurement light irradiating the sample. The polarization control element (1) is preferably disposed in the optical path between the coupler (1) and the objective lens.

[0052] Depending on the size, shape, and photographic environment of the sample, the detector (the part with the objective lens) needs to be moved at various angles to take pictures. If the bending of the optical fiber transmitting the measurement light changes accordingly, the polarization state of the measurement light may sometimes change.

[0053] By incorporating a polarization control element (1) together with the collimator for the reference light described above, it is possible to more accurately compensate for changes in the polarization state of the measurement light caused by the bending of the optical fiber.

[0054] The polarization state can be adjusted, for example, by observing the OCT signal. By observing two orthogonal polarization OCT signals, the polarization-induced stripe patterns in the image are reversed in intensity, and the adjustment is made to maximize the contrast between the intensity of each stripe pattern. This allows the polarization state to be set to be optimal for polarization-sensitive OCT.

[0055] The polarization control element (1) can also be set on the outside of the OCT device frame. With this configuration, it is easy to adjust to the optimal polarization state that is suitable for the sample to be photographed, especially when carrying the detector for imaging.

[0056] A polarization control element may also be provided in the optical path between the coupler (1) and the collimator for the reference light. However, in the OCT device disclosed herein, since the optical path length can be adjusted by the collimator for the reference light, it is not necessary to provide a polarization control element in the above-mentioned location.

[0057] The measurement light that illuminates the sample is reflected by the sample and becomes the reflected light (sample light), which is then combined with the reference light that has passed through the reference light using a collimator to become interference light.

[0058] Furthermore, in the OCT device disclosed herein, the collimator for the reference beam also functions as a reference surface. Therefore, there is no need to set up a separate reference mirror or other reference surface.

[0059] The OCT apparatus disclosed herein preferably includes a coupler (2) that combines the reflected light of the measurement light with the reference light. In this case, it is preferable that the reference light is collimated and placed in the optical path of the reference light between the coupler (1) and the coupler (2).

[0060] The reflected light of the measured light being combined can be light that has passed through the coupler (1).

[0061] The aforementioned interference light can also be split into two by the coupler (2) and emitted.

[0062] Alternatively, a polarization control element (also called polarization control element (2)) may be set in the optical path between the collimator and the coupler (2) of the reference light, and in the optical path of the measurement light between the coupler (1) and the coupler (2).

[0063] The OCT device disclosed herein obtains a signal representing the polarization characteristics of the sample from the aforementioned interference light. Preferably, the OCT device of this disclosure includes a detector for detecting the interference signal based on the aforementioned interference light. The detector is preferably a differential light detector, and may also have a signal amplification function. Alternatively, an amplifier may be provided separately.

[0064] The OCT device disclosed herein preferably includes: a polarization beam splitter that splits the interference light into a vertical polarization component and a horizontal polarization component; a vertical polarization-sensitive detector that detects the vertical polarization component; and a horizontal polarization-sensitive detector that detects the horizontal polarization component.

[0065] By adopting such a structure, information on polarization components from both the vertical and horizontal sides can be obtained, and tomographic images that better reflect the polarization characteristics of the sample can be obtained.

[0066] The polarization beam splitter is preferably placed in the optical path between the coupler (2) and the vertically polarized sensitive detector or the horizontally polarized sensitive detector.

[0067] In addition, the polarization beam splitter is preferably placed on the respective optical paths of the interference light split into two by the coupler (2).

[0068] A polarization control element (also called a polarization control element (3)) can also be placed in the optical path between the coupler (2) and the polarization beam splitter.

[0069] There are no particular limitations on the interferometers that can be used in the OCT apparatus disclosed herein, and examples include the Michelson interferometer and the Mach-Zehnder interferometer.

[0070] Types of OCTs that can be used in the OCT apparatus disclosed herein include time-domain OCT (TD-OCT) and Fourier-domain OCT (FD-OCT). Among FD-OCTs, examples include spectral-domain OCT (SD-OCT) and swept-source OCT (SS-OCT). Of these, SS-OCT is preferred due to its high sensitivity and deep measurability.

[0071] The OCT apparatus disclosed herein preferably further includes a collimator for converting the measurement light into parallel light. The collimator for the measurement light is preferably disposed in the optical path between the light source and the objective lens, more preferably disposed in the optical path between the coupler (1) and the objective lens, and even more preferably disposed in the optical path between the polarization control element (1) and the objective lens.

[0072] From the viewpoint of improving lateral resolution, it is preferable to use a collimating lens with a large diameter as the collimator for measuring light. The diameter of the collimator for measuring light is preferably 2 mm or more, more preferably 4 mm or more, and from the viewpoint of detector portability, it is preferably 12 mm or less.

[0073] The OCT apparatus disclosed herein preferably further includes a scanning mirror for scanning the measurement light illuminating the sample. The scanning mirror is preferably disposed in the optical path between the light source and the objective lens, more preferably disposed in the optical path between the coupler (1) and the objective lens, and even more preferably disposed in the optical path between the collimator for the measurement light and the objective lens.

[0074] Examples of scanning mirrors include galvanometer mirrors, polygon mirrors, and MEMS mirrors. Among these, galvanometer mirrors are preferred, single-axis or dual-axis galvanometer mirrors are more preferred, and dual-axis galvanometer mirrors are even more preferred.

[0075] The OCT device disclosed herein preferably further includes a driving device for driving the aforementioned scanning mirror.

[0076] The OCT apparatus disclosed herein preferably further includes a data acquisition (DAQ) device that collects interference signals based on measurement light and reference light. The DAQ device preferably includes an A / D converter. The DAQ device preferably converts the collected interference signals into digital data.

[0077] The OCT apparatus disclosed herein preferably further includes a computing unit that generates an optical coherence tomography image based on the interference signal of the measurement light and the reference light. The computing unit visualizes the interference signal according to characteristics such as intensity, thereby generating the optical coherence tomography image.

[0078] The OCT device disclosed herein preferably further includes a display device for displaying the obtained optical coherence tomography (OCT) image. The display device can be fixed or portable, but a portable device is preferred because it allows for image review at the shooting location. Furthermore, the connection to the computing device can be wired or wireless. There can be one or multiple display devices.

[0079] In the OCT device disclosed herein, the device or component for light incident or emission can be connected by an optical fiber. As the optical fiber mentioned above, single-mode fiber (SMF) is preferred. The optical fiber incident on the polarization beam splitter (the optical fiber forming the optical path between the coupler (2) and the polarization beam splitter) may also be polarization-maintaining fiber (PFM).

[0080] exist Figure 1 An example of the OCT device of this disclosure is shown, but the OCT device of this disclosure is not limited thereto.

[0081] exist Figure 1 In the OCT device 100, a wavelength scanning light source 101 outputs light used in the OCT. The wavelength scanning light source 101 outputs a trigger signal each time a frequency scan begins. In addition, a K-clock signal is output for sampling at equal frequency intervals by detecting the light using a Mach-Zehnder interferometer.

[0082] The light output from the wavelength scanning light source 101 is split into measurement light for irradiating the sample and reference light for reference in the coupler 103 via the optical fiber 102 at an intensity ratio of 90:10.

[0083] The measurement light is transmitted to the detector 106 through an optical fiber 104 several meters long. A polarization control element 105 is provided in the optical fiber 104 to compensate for changes in the polarization state of the measurement light.

[0084] In detector 106, the measurement light is converted into parallel light by collimator 107, then reflected by galvanometer mirror 108 and incident on objective lens 109. Galvanometer mirror 108 is driven by galvanometer mirror driver (not shown) to scan the parallel light in the XY direction perpendicular to the optical axis. The parallel light incident on objective lens 109 converges on the sample 110, which is the object of photography, and is reflected on the sample surface as reflected light (sample light) and returns to coupler 103 through the same optical path, exits onto optical fiber 111, and is incident on coupler 118 through polarization control element 112.

[0085] On the other hand, the reference light emitted from the coupler 103 passes through the optical fiber 113 and becomes parallel light through the collimator 115 provided by the upstream optical path length adjustment module 114. The parallel light is then guided to the optical fiber 116 through the reverse mode collimator 115 provided by the downstream optical path length adjustment module 114.

[0086] The upstream and downstream optical path length adjustment modules 114 each have a collimator 115, and are configured with two collimators 115 facing each other. Figure 2 A schematic diagram of the optical path length adjustment module 114 is shown. The optical path length adjustment module 114 includes: an angle adjustment holder 114a that holds the collimator 115 in a manner capable of two-axis (XY) angle adjustment; a fixing member 114b for fixing the angle adjustment holder 114a to a frame; and an optical fiber connector 114c for connecting optical fibers 113 or 116. By moving the angle adjustment holder 114a, the angle of the collimator 115 is adjusted, thereby adjusting the optical path length of the reference light.

[0087] In addition, Figure 2 In the case of the optical cage, the angle adjustment retainer 114a is fixed to the frame by the fixing component 114b. However, the fixing component 114b may not be used. Instead, multiple steel rods are used to connect the angle adjustment retainers 114a on the upstream and downstream sides to form an optical cage system.

[0088] The reference light emitted from the downstream optical path length adjustment module 114 passes through the optical fiber 116 and the polarization control element 117 and is incident on the coupler 118, where it combines with the sample light to become interference light.

[0089] The interference light is split into two by coupler 118. One side passes through optical fiber 119 and polarization control element 120 and is incident on polarization beam splitter 121. The other side passes through optical fiber 124 and polarization control element 125 and is incident on polarization beam splitter 126.

[0090] The interference light incident on polarization beam splitters 121 and 126 is split into a horizontal polarization component and a vertical polarization component. The horizontal polarization component is incident on a horizontal polarization sensitive detector 129 through optical fibers 122 and 127, and the vertical polarization component is incident on a vertical polarization sensitive detector 130 through optical fibers 123 and 128.

[0091] The horizontal polarization-sensitive detector 129 and the vertical polarization-sensitive detector 130 detect interference signals based on the horizontal polarization component and the vertical polarization component of the interference light, respectively.

[0092] The detected interference signal is collected by the DAQ device (A / D converter) (not shown) in the control unit (not shown) and converted into digital data. The collection of the interference signal is initiated by a trigger signal emitted by the wavelength scanning light source 101 and is synchronized with the K clock signal.

[0093] The computing device in the control unit generates an optical coherence tomography image of the sample 110 based on the interference signal converted by the DAQ device, and displays it on a movable display (not shown).

[0094] The OCT device disclosed herein is preferably configured such that the user can carry the objective lens while performing tomographic imaging. By making the objective lens portable, images can be taken from various positions and angles depending on the size and shape of the sample. Furthermore, the vertical and horizontal polarization components of the interference light can be obtained along the polarization axis of the sample.

[0095] When the part with the objective lens is made portable, the optical path length of the measuring light is prone to change during imaging. However, the OCT device disclosed herein can obtain tomographic images that better reflect the polarization characteristics of the sample because the optical path length of the reference light can be adjusted by using a collimator for the reference light.

[0096] The aforementioned part with an objective lens is, for example, a detector of an OCT device, and preferably, in addition to the objective lens, it also has a collimator for measuring light, a scanning mirror, etc.

[0097] The OCT device disclosed herein is preferably configured such that the user can hold the part with the objective lens to perform tomography, and more preferably configured such that the user can hold the part with the objective lens with one hand to perform tomography.

[0098] In addition to the objective lens, the OCT device disclosed herein may also include a part that the user can carry during tomography. Such a part may include, for example, a display device.

[0099] In the OCT apparatus disclosed herein, it is preferable that the portion equipped with the objective lens is connected to the portion without the objective lens via an optical fiber, and the measurement light and its reflected light (sample light) are transmitted through the optical fiber. In this manner, even when the subject is located far from the portion without the objective lens, the portion equipped with the objective lens can be positioned near the subject for tomographic imaging by adjusting the length of the optical fiber. Furthermore, since a wired optical fiber is used, high-resolution OCT measurements can be performed even for subjects located far from the portion without the objective lens.

[0100] The length of the aforementioned optical fiber is not particularly limited and can be determined based on the location of the photographed subject. For example, it can be 0.5m or more, preferably 1m or more. Alternatively, it can be less than 5m, preferably less than 3m.

[0101] By setting it within the aforementioned range, it is easy to perform tomography while simultaneously operating the equipment (polarization control element, etc.) configured in the main body (frame) of the OCT device and carrying the part equipped with the objective lens.

[0102] The aforementioned non-carried parts include, for example, the main body (frame) of the OCT device, which preferably includes a light source, polarization control elements, a collimator for reference light, a detector, a DAQ device, and a computing device.

[0103] In cases where there is a carried portion in addition to the portion with the objective lens, the connection between this portion and the portion with the objective lens or the portion without the carried portion is not necessarily limited to an optical fiber-based connection; for example, it can also be a wire-based connection.

[0104] The OCT apparatus disclosed herein is preferably configured to acquire the vertical and horizontal polarization components of the interference light along the polarization axis of the sample. This allows for the acquisition of tomographic images that better reflect the polarization characteristics of the sample.

[0105] The above structure can be achieved, for example, by making the part with the objective lens (detector) portable.

[0106] Figure 3 Another example of the OCT device of this disclosure is shown (an example in which the part with the objective lens is portable), but the OCT device of this disclosure is not limited thereto.

[0107] exist Figure 3 In the middle, the user 201 carries the detector 202 of the OCT device with one hand. The detector 202 is connected to the frame 204 of the OCT device via optical fiber 203.

[0108] The housing 204 houses a light source, a polarization control element, a collimator for the reference light, a galvanometer mirror driver, a detector, a DAQ device, and a computing unit. Additionally, a polarization control element 205 for measuring light is located outside the housing 204, which can be operated by the user 201 during tomography.

[0109] The OCT apparatus disclosed herein is applicable to all polarization-sensitive optical coherence tomography regardless of the field. In particular, it can be used on a wide variety of samples, and is suitable for applications where the optical path length of the measurement light can vary depending on the sample and the imaging environment, such as in physical chemistry and industrial fields.

[0110] The OCT device disclosed herein is preferably an OCT device for physicochemical or industrial use, and more preferably for industrial use.

[0111] The embodiments have been described above; however, it should be understood that various changes in form or details may be made without departing from the spirit and scope of the claims.

[0112] Example

[0113] The present disclosure will now be described in more detail by way of examples, but the present disclosure is not limited to these examples.

[0114] Example 1

[0115] Use with Figure 1 The polarization-sensitive OCT device shown was used to perform OCT photography on the side of the cap of a solid stick (KIEIRO PIT N, PT-NC) manufactured by Tombow Pencil Co.

[0116] As the OCT light source, a high-speed wavelength scanning light source (center wavelength: 1060nm, scanning width: 140nm, repetition frequency: 50kHz) manufactured by Excelitas was used as the reference collimator. Two sets of structures were configured opposite each other as follows: the F280APC-1064 manufactured by Thorlabs was connected to the collimator adapter (AD1109 manufactured by Thorlabs) and held in the kinematic support (KC05-T / M manufactured by Thorlabs).

[0117] Through the aforementioned OCT imaging, sample images based on light waves vibrating in the horizontal direction (P-polarized waves) and sample images based on light waves vibrating in the vertical direction (S-polarized waves) were obtained. Gaussian filtering was applied to all sampled images to remove noise. Background information (BG images) was removed from the respective P-polarized and S-polarized wave sample images to obtain the P-polarized wave image and the S-polarized wave image.

[0118] A phase difference image is generated by processing all pixels of the obtained P-polarized wave image and S-polarized wave image based on the following formula.

[0119]

[0120] (In the formula, I) p (x, z) and I s (x, z) represent the interference signals of the P-polarized and S-polarized waves after background information has been removed, respectively.

[0121] The obtained P-polarized wave image, S-polarized wave image, and phase difference image are respectively in Figure 4 of (a) Figure 4 (b) and Figure 4 As shown in (c).

[0122] The image shows interference fringes unique to the sample, which well reflect the polarization characteristics of the sample.

[0123] Example 2

[0124] Using the same polarization-sensitive OCT apparatus as in Example 1, OCT imaging was performed on a fine-patterned NBS 1963A resolution test target (Thorlabs R2L2S1P1). The resulting OCT images are shown below. Figure 5 .

[0125] It can clearly identify details down to the micrometer level, achieving high lateral resolution.

[0126] Label Explanation

[0127] 100: OCT device; 101: Wavelength scanning light source; 102, 104, 111, 113, 116, 119, 122, 123, 124, 127, 128: Fiber optic cables; 103, 118: Couplers; 105, 112, 117, 120, 125: Polarization control elements; 106: Detector; 107: Collimator; 108: Galvanometer reflector; 109: Objective lens; 110: Sample; 114: Optical path length adjustment module; 114a: Angle adjustment retainer; 114b: Fixed component; 114c: Fiber optic connector; 115: Collimator; 121, 126: Polarization beam splitters; 129: Horizontal polarization-sensitive detector; 130: Vertical polarization-sensitive detector; 201: User; 202: Detector; 203: Optical fiber; 204: Frame; 205: Polarization control element.

Claims

1. A polarization-sensitive optical coherence tomography apparatus, which obtains a signal representing the polarization characteristics of the sample from the interference light of reflected light from a measurement light irradiating a sample and a reference light used for reference, wherein, The polarization-sensitive optical coherence tomography apparatus includes two collimators for the reference light arranged opposite each other in the optical path of the reference light. The optical path length of the reference light is adjusted using a collimator.

2. The polarization-sensitive optical coherence tomography apparatus according to claim 1, wherein, The optical path of the measuring light irradiating the sample includes a polarization control element for adjusting the polarization state of the measuring light.

3. The polarization-sensitive optical coherence tomography apparatus according to claim 1 or 2, wherein, The polarization-sensitive optical coherence tomography apparatus includes a coupler (1) that splits light from a light source into a measurement light and a reference light that illuminate the sample, wherein the intensity ratio of the measurement light to the reference light is 60:40 to 95:

5.

4. The polarization-sensitive optical coherence tomography apparatus according to any one of claims 1 to 3, wherein, The polarization-sensitive optical coherence tomography apparatus includes: a polarization beam splitter that splits the interference light into a vertical polarization component and a horizontal polarization component; a vertical polarization-sensitive detector that detects the vertical polarization component; and a horizontal polarization-sensitive detector that detects the horizontal polarization component.

5. The polarization-sensitive optical coherence tomography apparatus according to any one of claims 1 to 4, wherein, As light from a light source, light with a center wavelength in the range of 950nm to 1400nm is used.

6. The polarization-sensitive optical coherence tomography apparatus according to any one of claims 1 to 5, wherein, The polarization-sensitive optical coherence tomography device has a wavelength scanning light source, the wavelength scanning width of the light from the wavelength scanning light source is 100nm to 200nm, and the repetition scanning frequency is 30kHz to 120kHz.

7. The polarization-sensitive optical coherence tomography apparatus according to any one of claims 1 to 6, wherein, The polarization-sensitive optical coherence tomography device is configured such that the user can carry the part equipped with the objective lens while performing tomography.

8. The polarization-sensitive optical coherence tomography apparatus according to any one of claims 1 to 7, wherein, The polarization-sensitive optical coherence tomography apparatus is configured to obtain the vertical and horizontal polarization components of the interference light according to the polarization axis of the sample.

9. The polarization-sensitive optical coherence tomography apparatus according to any one of claims 1 to 8, wherein, The polarization-sensitive optical coherence tomography device has a variable focal length lens.

10. The polarization-sensitive optical coherence tomography apparatus according to any one of claims 3 to 9, wherein, The polarization-sensitive optical coherence tomography device includes: An optical path length adjustment module, which has a collimator for the reference light in the optical path of the reference light; Coupler (2) that combines the reflected light of the measurement light with the reference light; A collimator for measuring light, which converts the measuring light into parallel light; and A scanning mirror that scans the measurement light illuminating the sample. There is no polarization control element in the optical path between the coupler (1) and the collimator for the reference light. The two reference light collimators are arranged opposite each other in a manner that is approximately in a straight line. The angle and / or position of the collimator used for the reference light are variable. The optical path length adjustment module includes holding components for holding the collimator used for the reference light. The holding component can adjust the angle and / or position of the collimator for the reference light.

11. The polarization-sensitive optical coherence tomography apparatus according to any one of claims 1 to 10, wherein, The polarization-sensitive optical coherence tomography device is for industrial use.

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