Optical coherence tomography (OCT)-based light splitting frequency doubling method and measuring system

Abstract

The invention discloses an OCT-based light splitting frequency doubling method and a measuring system, and relates to the technical field of optical coherence tomography, and the method comprises the following steps: a light beam emitted by a light source is divided into a first light path and a second light path through an optical fiber coupler, the first light path is transmitted to a collimating lens group through a scanning detection part optical fiber interface, and is transmitted to a second light path through a two-dimensional scanning part; scanning an object to be measured through a focusing lens; a second light path enters the reference arm part, sequentially passes through the polarization regulator and the reference arm collimating mirror group and then is reflected by the reference arm reflecting mirror group; the first light path and the second light path interfere with each other in the optical fiber coupler, and interference light enters the light splitting path detection component after being generated. Interference light is dynamically distributed to multiple detector channels through the light splitting element, efficient multiplexing of a light path is achieved, and different sampling rate and resolution requirements are flexibly met under the control of the main control card through three modes of light splitting, optical switch switching and scanning light splitting.

Description

Technical Field

[0001] The present invention relates to the technical field of optical coherence tomography, and in particular to an OCT-based light splitting and frequency doubling method and measurement system. Background Art

[0002] Optical coherence tomography is a non-contact, high-resolution, and high-sensitivity imaging method. Its basic principle is to use a low-coherence interference light source to perform cross-sectional imaging of the internal microstructure of the sample through interference imaging. In conventional OCT systems, the low-coherence light emitted by the light source is usually divided into two optical paths by an optical fiber beam splitter: one is the sample arm optical path, which is used to illuminate the sample to be tested and collect the reflected signal; the other is the reference arm optical path, which is used to form an interference signal with the sample reflected light. In order to improve image resolution and signal-to-noise ratio, existing OCT systems generally introduce optical components such as collimators, focusing lenses, and scanning mirrors to form a two-dimensional scanning structure to enhance the continuity and stability of image acquisition. With the increasing requirements for imaging depth and accuracy, variant technologies based on the spectral domain and the frequency scanning domain are also gradually developing.

[0003] Traditionally, laser welding has relied on imaging to inspect welds. However, this approach, due to its limited depth measurement capabilities and low resolution, is poor at identifying subtle defects, and cannot accurately capture internal conditions. This leads to poor data accuracy and repeatability, significantly impacting weld quality assessment. Compared to traditional approaches, OCT offers significant advantages: real-time imaging, which rapidly captures dynamic changes in the welding process; depth measurement capabilities, which directly capture the depth of the weld; and high data accuracy and repeatability. Through precise optical measurement and signal processing, it provides a reliable basis for welding quality assessment and process optimization.

[0004] However, during welding, the molten pool forms and solidifies extremely quickly (in milliseconds or even microseconds), and defects (such as pores and lack of fusion) can occur in an instant. High-speed laser welding (speeds > 10 m / min) requires extremely high acquisition speeds: kHz (thousands of times per second) or even MHz. OCT sampling frequency is limited by the sensor sampling frequency, and its application in the laser welding field still presents significant challenges. Summary of the Invention

[0005] In view of the above-mentioned existing problems of spectral domain and swept frequency domain OCT technologies, the present invention is proposed.

[0006] Therefore, the present invention provides an OCT spectroscopic frequency doubling method to solve the inherent sampling rate of sensors in the prior art and achieve a doubling, tripling or even multiple-fold increase in the sampling frequency.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0008] In a first aspect, the present invention provides an OCT-based optical fiber splitting and frequency doubling method, comprising: splitting a light beam emitted by a light source into a first light path and a second light path through an optical fiber coupler;

[0009] The first optical path is transmitted to the collimating lens group through the optical fiber interface of the scanning detection part, passes through the two-dimensional scanning part, and scans the object to be measured through the focusing lens;

[0010] The second light path enters the reference arm component, passes through the polarization adjuster and the reference arm collimator assembly in sequence, and is then reflected by the reference arm reflector assembly;

[0011] The first optical path and the second optical path interfere with each other in the optical fiber coupler, and the generated interference light enters the light splitting detection component;

[0012] Performing optical mode processing on the interference light through a beam splitter;

[0013] The continuous spectrum is divided into multiple paths by a dichroic mirror / polarization beam splitter / beam splitter prism to form a spectral splitting mode;

[0014] The optical paths are alternately distributed through the optical splitter element to form an optical switch mode;

[0015] Dynamically distribute the light path through the galvanometer / MEMS / DMD / LCOS components to form a scanning spectroscopic mode;

[0016] The spectral spectrometry mode, the optical switch switching mode and the scanning spectrometry mode enter the detector channel, the detector channel and the detector channel respectively.

[0017] As a preferred solution of the OCT spectroscopic frequency multiplication method described in the present invention, the signal processing host sends phase-difference T and n timing signals to the detector, the detector, and the trigger pin of the detector by controlling the main control card;

[0018] Where n is the number of detectors and T is the detector sampling period.

[0019] As a preferred solution of the OCT spectroscopic frequency doubling method described in the present invention, the staggered exposure of the detector array is controlled by the phase-difference T and n timing signals, so that detectors 1, 2 and 3 form complementary sampling windows in the time domain, thereby doubling the total sampling frequency.

[0020] As a preferred solution of the OCT spectroscopic frequency doubling method described in the present invention, the signal processing host performs timestamp synchronization alignment processing on detectors 1, 2 and 3, regards the data of different detectors as data collected by the same detector at different times, executes the optical parameter difference compensation algorithm, corrects the transmission loss of the split light path, performs interference signal splicing and reconstruction, and generates a complete axial scanning signal.

[0021] In a second aspect, the present invention provides an OCT-based spectroscopic frequency doubling measurement system, comprising a light source, a fiber coupler, a signal processing host, a reference arm component, a scanning detection component, and an object to be measured;

[0022] The detector lens assembly includes a spectroscopic element, detector 1, detector 2 and detector 3;

[0023] The reference arm component includes a polarization adjuster, a collimator lens group and a reflector lens group;

[0024] The scanning detection component includes an optical fiber interface, a collimating lens group, a two-dimensional scanning part, and a focusing lens.

[0025] As a preferred solution of the OCT spectroscopic frequency doubling method described in the present invention, the input end of the detector mirror group is connected to the common end of the fiber coupler through an optical fiber, and the output end of the detector mirror group maintains a conjugate relationship with the optical incident surface of the spectroscopic element.

[0026] As a preferred solution of the OCT-based frequency splitting and doubling method described in the present invention, the input end of the polarization adjuster is connected to the output end of the fiber coupler through a single-mode optical fiber, and the output end of the polarization adjuster is fused to the optical fiber interface of the collimating lens group.

[0027] As a preferred solution of the OCT-based splitting and frequency doubling method described in the present invention, the input end of the optical fiber interface is connected to the output end of the optical fiber coupler through a single-mode optical fiber, and the output end of the optical fiber interface is fused with the optical fiber interface of the collimating lens group.

[0028] In a third aspect, the present invention provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: when the computer program is executed by the processor, any step of the OCT spectroscopic frequency doubling method as described in the first aspect of the present invention is implemented.

[0029] In a fourth aspect, the present invention provides a computer-readable storage medium having a computer program stored thereon, wherein: when the computer program is executed by a processor, any step of the OCT spectroscopic frequency doubling method as described in the first aspect of the present invention is implemented.

[0030] The beneficial effects of the present invention are as follows: the interference light is dynamically distributed to multiple detector channels through the spectroscopic element, thereby realizing efficient multiplexing of the optical path; through the three modes of spectroscopic, optical switch switching and scanning spectroscopic, it is flexibly adapted to different sampling rates and resolution requirements under the control of the main control card; it can select the optimal spectroscopic strategy according to the characteristics of the object to be measured, thereby improving the utilization rate of the interference signal and reducing optical crosstalk; by sending trigger signals with a phase difference of T / n to multiple detectors, the staggered exposure of each channel is accurately controlled, and complementary sampling windows are formed in the time domain; combined with the timestamp synchronization alignment and optical parameter difference compensation algorithm, the timing jitter of multi-channel acquisition and the difference in optical path transmission are eliminated, ensuring that the interference signal after frequency doubling sampling remains consistent in the time-space dimension, and ultimately achieving high-fidelity axial scanning signal reconstruction. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 This is a flow chart of the OCT-based spectroscopic frequency doubling method.

[0033] Figure 2 Schematic diagram of the frequency-doubling high-speed acquisition OCT system with a split light path.

[0034] Figure 3 This is a flow chart of the logic scheme of the optical splitting path double frequency high-speed acquisition OCT system.

[0035] Figure 4 This is a flow chart of the logic scheme of the optical multi-frequency high-speed acquisition OCT system.

[0036] Figure 5 This is a flow chart of the multi-channel frequency doubling scheme based on optical switches.

[0037] Figure 6 The flowchart of the multi-channel frequency doubling scheme based on the optical splitter element.

[0038] Figure 7 The flowchart of the multi-channel frequency doubling scheme based on scanning spectrometer elements.

[0039] In the figure: 1. Light source, 2. Fiber optic coupler, 31. Detector lens assembly, 32. Spectrometer, 33. Detector 1, 34. Detector 2, 35. Detector 3, 41. Polarization adjuster, 42. Reference arm collimator lens assembly, 43. Reference arm reflector assembly, 51. Fiber optic interface, 52. Collimator lens assembly, 53. Two-dimensional scanning part, 54. Focusing lens, 6. Signal processing host, 7. Control main control card, 8. Object to be measured. DETAILED DESCRIPTION

[0040] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0041] In the following description, many specific details are set forth to facilitate a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0042] Secondly, the term "one embodiment" or "embodiment" herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The phrase "in one embodiment" appearing in various places throughout this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive of other embodiments.

[0043] Reference Figures 1 to 4 , is an embodiment of the present invention, which provides an OCT-based frequency doubling method, comprising the following steps:

[0044] The light beam emitted by the light source 1 is divided into a first light path and a second light path through the optical fiber coupler 2.

[0045] Furthermore, the light beam emitted by light source 1 is split into a first optical path and a second optical path by fiber coupler 2. The first optical path is transmitted through the optical fiber interface 51 of the scanning detection section to the collimator lens assembly 52, where it scans the object 8 under test via the two-dimensional scanning section 53 and focusing lens 54. The second optical path enters the reference arm assembly, passes through the polarization adjuster 41 and the reference arm collimator lens assembly 42, and is reflected by the reference arm reflector assembly 43. The light reflected from the object 8 carried by the first optical path interferes with the light reflected from the reference arm in the second optical path in the fiber coupler 2. The resulting interference light enters the light path splitting detection component for subsequent processing.

[0046] The first light path is transmitted to the collimating lens group 52 through the optical fiber interface 51 of the scanning detection part, guided by the two-dimensional scanning part 53 and the focusing lens 54, and scans the object to be measured 8 through the focusing lens 54.

[0047] Furthermore, the first optical path is transmitted to the collimating lens group 52 through the optical fiber interface 51 of the scanning detection part to form a collimated light beam. The collimated light beam is converged to the surface of the object to be measured 8 through the focusing lens 54 through the two-dimensional scanning part 53 to form a scanning spot. After the scanning spot is reflected on the surface of the object to be measured 8, it carries the object information and returns along the original optical path. The two-dimensional scanning part 53 controls the scanning spot to move along a predetermined trajectory on the surface of the object to be measured 8. The return light beam returns to the detection optical path. The focusing lens 54 ensures that the scanning spot has the best focusing effect on the surface of the object to be measured 8, so that the return light beam carries clear object morphology information. The return light beam interferes with the reference arm light beam in the optical fiber coupler 2 to form an interference signal carrying the object depth information, which is collected by the main control card 6 and transmitted to the signal processing host 7 to reconstruct the three-dimensional structure image of the object to be measured 8.

[0048] The second light path enters the reference arm component, passes through the polarization adjuster 41 and the reference arm collimator lens assembly 42 in sequence, and is then reflected by the reference arm reflector assembly 43 .

[0049] Furthermore, after the second light path enters the reference arm component, the polarization state of the light beam is first precisely controlled by the polarization adjuster 41 to ensure that it matches the polarization of the first light path; the light beam after polarization adjustment enters the reference arm collimator group 42 and is converted into a collimated parallel light beam; the collimated light beam is transmitted to the reference arm reflector group 43 and then reflected by the original path, and the reflected light beam maintains the same polarization characteristics and wavefront characteristics as the incident light beam; the reflected light beam returns along the original light path and passes through the reference arm collimator group 42 again, and is re-coupled into the transmission optical fiber; the return light beam carries stable reference light information and is transmitted to the optical fiber coupler 2, and interferes with the first light path returned from the object to be measured 8.

[0050] The first optical path and the second optical path interfere with each other in the optical fiber coupler 2, and the generated interference light enters the optical path detection component.

[0051] Furthermore, the reflected light from the object to be measured 8 carried by the first optical path interferes with the reference light reflected by the reference arm reflector group 43 in the second optical path in the optical fiber coupler 2. When the two beams of light meet the coherence condition, stable interference fringes are generated. The interference light intensity distribution contains the depth information of the object to be measured 8. The optical fiber coupler 2 adopts a 2×2 single-mode polarization-maintaining fiber structure to ensure the polarization state matching and phase stability of the two optical paths.

[0052] The interference light is subjected to optical mode processing by the spectroscopic element 32 .

[0053] Furthermore, after receiving the interference light from the fiber coupler 2, the spectroscopic element 32 uses a dichroic mirror / polarization beam splitter / beam splitter prism to split the continuous spectrum into multiple independent light beams according to the wavelength range according to the parameters set by the working mode selector to form a spectral spectroscopic mode, or drives the high-speed optical switch array through a logic control element to alternately direct the interference light to different output ports according to a preset timing to form an optical switch switching mode, or controls the deflection angle of the reflective surface of the galvanometer / MEMS / DMD / LCOS component to dynamically distribute the light beam to different spatial positions to form a scanning spectroscopic mode.

[0054] The continuous spectrum is split into multiple paths by a dichroic mirror / polarization beam splitter / beam splitter prism to form a spectral splitting mode.

[0055] Furthermore, after the interference light output from the fiber coupler 2 enters the detector lens assembly 31, it is first transmitted to the optical input surface of the beam splitter element 32. This optical input surface maintains a conjugate relationship with the output end of the detector lens assembly 31 to ensure the focusing consistency of the light beam in the spatial propagation path. Subsequently, the interference light is separated within the beam splitter element 32 according to its wavelength characteristics. For example, under the action of a dichroic mirror, light of different wavelengths is reflected or transmitted in different directions, or under the action of a polarization beam splitter, the light is split into two orthogonal polarization components according to the polarization state, or under the action of a beam splitter prism, the dispersion effect of the material is utilized to cause light of different wavelengths to be emitted at different angles. The multiple optical path signals thus formed correspond to different spectral intervals of the original interference light and enter the corresponding detector channels in sequence according to a predetermined optical path distribution. One optical path enters the detector channels 1 and 33, another enters the detector channels 2 and 34, and another enters the detector channels 3 and 35. Each optical path signal completes the photoelectric conversion process on its respective detector, thereby achieving spectral separation processing of the interference light.

[0056] The optical paths are alternately distributed by the light splitting element 32 to form an optical switch mode.

[0057] Furthermore, in the propagation path of the interference light before completing the photoelectric conversion, the logic control element dynamically controls the optical path in the time domain. The logic control element controls the on-off state of the optical switch according to the preset timing signal, so that the optical path switches between different channels in a set order. For example, at a certain moment, the optical signal is allowed to enter the detector 1 and 33 channels, and at the next moment it is switched to the detector 2 and 34 channels, and at the next moment it is switched to the detector 3 and 35 channels. The mechanical or electro-optical components inside the optical switch are driven by electrical signals to achieve rapid switching of the optical path direction, ensuring that only one optical path signal is guided to the corresponding detector channel at each moment, and the remaining channels are in an isolated state. By periodically repeating the above switching action, the interference light in different time periods enters different detector channels respectively, thereby realizing the alternating distribution of optical paths between multiple channels in the time dimension, and finally forming an optical switch switching mode.

[0058] The optical path is dynamically allocated through the galvanometer / MEMS / DMD / LCOS components to form a scanning spectroscopic mode.

[0059] Furthermore, before entering the detector channel, the interference light is first guided to the reflective surface of the galvanometer, MEMS, DMD or LCOS component, which performs angle deflection or spatial light modulation according to a preset control signal. The galvanometer is driven by a motor to achieve mechanical angle adjustment, the MEMS uses a micro-electromechanical system to achieve fast and controllable mirror deflection, the DMD uses a digital micromirror device to perform pixel-by-pixel spatial modulation of the light beam, and the LCOS combines liquid crystal technology and complementary metal oxide semiconductor technology to achieve phase-type or reflective light control. The above components periodically change the propagation direction of the light beam according to the instructions of the control signal, so that the interference light is directed to detectors 1, 33 channels, detectors 2, 34 channels or detectors 3, 35 channels according to the set path. This process realizes the dynamic allocation of the optical path in the spatial dimension and is combined with time synchronization control so that the interference light in different time periods is directed to different detector channels, thereby constructing a scanning spectroscopic pattern in both spatial and temporal dimensions.

[0060] The spectral spectrometry mode, optical switch switching mode and scanning spectrometry mode enter detector 1, 33 channels, detector 2, 34 channels and detector 3, 35 channels respectively.

[0061] Furthermore, in the spectral spectrometry mode, the multi-path interference light signals corresponding to different wavelength ranges after being processed by the spectrometer 32 are guided to the corresponding detector channels according to their propagation directions, wherein the light in a specific wavelength range enters the detector channels 1 and 33, the light in another wavelength range enters the detector channels 2 and 34, and the light in the remaining wavelength ranges enters the detector channels 3 and 35. In the optical switch switching mode, the logic control element controls the state switching of the optical switch according to a preset timing, so that the interference light enters the detector channels 1 and 33, the detector channels 2 and 34, and the detector channels 3 and 35 in different time periods, thereby realizing alternating channel allocation in the time domain. In the scanning spectrometry mode, the galvanometer, MEMS, DMD or LCOS component dynamically adjusts the light beam propagation path according to the control signal, directing the interference light to different detector channels in terms of spatial angle, so that the light signal in each time period enters only a designated detector channel. The above three spectrometry modes correspond to entering the detector channels 1 and 33, the detector channels 2 and 34, and the detector channels 3 and 35, respectively, and completing the photoelectric conversion process in their respective channels, thereby realizing multi-channel parallel collection of the interference light signal.

[0062] Sending phase-difference T, n timing signals to the trigger pins of detectors 1, 33, detectors 2, 34 and detectors 3, 35 through the signal processing host 6;

[0063] Where n is the number of detectors and T is the detector sampling period.

[0064] Furthermore, the signal processing host 6 generates a timing control signal with a phase difference according to the number of detectors n and the detector sampling period T, where n is 3, corresponding to detectors 1, 33, detectors 2, 34 and detectors 3, 35;

[0065] Specifically, with T as the basic sampling period on the time axis, the triggering moments of the three detectors are evenly staggered, so that detectors 1 and 33 are triggered at time point kT, detectors 2 and 34 are triggered at time point kT+T / 3, and detectors 3 and 35 are triggered at time point kT+2T / 3, where k is an integer representing the current sampling period number; the signal processing host 6 applies the above-mentioned timing signals to the enable / trigger pins of detectors 1 and 33, detectors 2 and 34, and detectors 3 and 35 respectively through electrical connection, so as to control each detector to start exposure and collect interference light signals at its corresponding time, thereby realizing staggered sampling of multiple detectors in the time domain, so that the sampling windows of each detector complement each other, thereby forming a frequency doubling effect with an equivalent sampling frequency three times the original sampling rate.

[0066] The staggered exposure of the detector array is controlled by the phase-difference T and n timing signals, so that detectors 1, 33, detectors 2, 34 and detectors 3, 35 form complementary sampling windows in the time domain, thereby doubling the total sampling frequency.

[0067] Furthermore, the signal processing host 6 generates three sets of trigger signals with phase differences according to the set number of detectors n of 3 and the detector sampling period T, which correspond to detectors 1, 33, detectors 2, 34 and detectors 3, 35 respectively. Each set of trigger signals applies a control pulse to the enable / trigger pin of its corresponding detector, so that detectors 1, 33 start to be exposed at time point, detectors 2, 34 start to be exposed at time point, and detectors 3, 35 start to be exposed at time point. Since there is a uniformly distributed phase difference at the start time of exposure of each detector, it is manifested on the time axis as their respective sampling windows are arranged in sequence and do not overlap with each other. The staggered exposure method makes the number of interference light signals collected by the three detectors per unit time equivalent to three times that of a single detector running at the original sampling period T, thereby achieving a three-fold increase in the total sampling frequency and constructing a continuous and complete sampling sequence in the time domain.

[0068] Specifically, the expression is,

[0069] W = R × hU;

[0070] Where W is the total sampling frequency, R is the single detector rate, and hU is the h-fold frequency increase.

[0071] The signal processing host 6 performs timestamp synchronization alignment processing on detectors 1, 33, detectors 2, 34 and detectors 3, 35, eliminates the timing deviation between channels, executes the optical parameter difference compensation algorithm, corrects the transmission loss of the split light path, performs interference signal splicing and reconstruction, and generates a complete axial scanning signal.

[0072] Furthermore, after detectors 1, 33, detectors 2, 34, and detectors 3, 35 complete the photoelectric conversion and output digital signals respectively, the output data of each channel carries the timestamp information generated by the respective triggering moments. Due to the inherent timing offset introduced by staggered exposure between the detectors, as well as the additional timing deviation caused by the hardware response delay difference, the signal processing host 6 aligns and corrects the timestamps of each channel according to the preset phase difference T / n relationship, so that the data of all channels maintain relative position consistency on the unified time axis; subsequently, in view of the transmission loss caused by factors such as the difference in optical path length and the inconsistent transmittance of optical components in different optical paths, the signal processing host 6 adopts an optical parameter difference compensation algorithm to normalize the amplitude of the interference signals output by detectors 1, 33, detectors 2, 34, and detectors 3, 35;

[0073] Specifically, it includes adjusting the gain coefficient according to the spectral response curve or polarization characteristics corresponding to each channel; after completing the timing alignment and amplitude correction, the signal processing host 6 further performs the interference signal splicing and reconstruction operation, connecting the multiple signal segments from detectors 1, 33, detectors 2, 34 and detectors 3, 35 in sequence according to their complementary order in the time domain to form a continuous and complete interference pattern. The reconstructed interference signal is used for axial scanning calculation to generate an axial scanning signal covering the complete measurement range.

[0074] This embodiment also provides an OCT-based spectroscopic frequency doubling measurement system, comprising: a light source 1, a fiber coupler 2, a main control card 6, a signal processing host 7, a reference arm component, a scanning detection component, and an object to be measured 8;

[0075] The detector lens assembly 31 includes a light splitting element 32, detectors 1, 33, detectors 2, 34 and detectors 3, 35;

[0076] The reference arm assembly includes a polarization adjuster 41, a collimator lens group 52 and a reflector group;

[0077] The scanning detection component includes an optical fiber interface 51 , a collimating lens group 52 , a two-dimensional scanning part 53 , and a focusing lens 54 .

[0078] The input end of the detector lens assembly 31 is connected to the common end of the fiber coupler 2 through an optical fiber, and the output end of the detector lens assembly 31 maintains a conjugate relationship with the optical incident surface of the beam splitter element 32 .

[0079] Furthermore, the input end of the detector lens assembly 31 is physically connected to a common port of the fiber coupler 2 using a single-mode optical fiber, so that the interference light output from the fiber coupler 2 can be transmitted to the inside of the detector lens assembly 31 via the optical fiber. The optical structure of the output end of the detector lens assembly 31 is designed to maintain a conjugate relationship with the optical incident surface of the beam splitter 32.

[0080] Specifically, it means that the exit surface of the last group of optical lenses of the detector lens group 31 and the incident surface of the spectrometer element 32 satisfy the Fourier transform pair relationship in the optical system, or satisfy the imaging conjugate surface condition, to ensure that the light beam output from the detector lens group 31 is in the correct spatial position and focusing state when entering the spectrometer element 32. The conjugate relationship is achieved through precision mechanical assembly, including adjusting the axial distance and angle between the detector lens group 31 and the spectrometer element 32, so that the light path maintains wavefront consistency during propagation, thereby ensuring the accuracy of subsequent spectroscopic processing.

[0081] The input end of the polarization adjuster 41 is connected to the output end of the fiber coupler 2 through a single-mode optical fiber, and the output end of the polarization adjuster 41 is fused to the optical fiber interface 51 of the collimating lens assembly 52 .

[0082] Furthermore, the input end of the polarization adjuster 41 is physically connected to an output port of the fiber coupler 2 using a single-mode optical fiber, so that the optical signal output from the fiber coupler 2 can enter the interior of the polarization adjuster 41, ensuring that the light maintains single-mode characteristics during transmission and avoiding the influence of mode dispersion on the interference performance; the polarization adjuster 41 manually or automatically adjusts the polarization state of the input light to match the polarization requirements of the subsequent optical path, and the output end of the polarization adjuster 41 is fused with the fiber interface 51 at the front end of the collimator group 52 through the fiber interface 51. The fusion process uses a fiber fusion splicer to discharge heat the end faces of the two optical fibers, so that they can achieve low-loss, high-strength permanent connection in a passive state. The polarization-controlled optical signal output by the polarization adjuster 41 can be stably transmitted to the collimator group 52, providing a basis for subsequent collimation processing.

[0083] The input end of the optical fiber interface 51 is connected to the output end of the optical fiber coupler 2 through a single-mode optical fiber, and the output end of the optical fiber interface 51 is fused with the optical fiber interface 51 of the collimating lens assembly 52 .

[0084] Furthermore, the input end of the optical fiber interface 51 is physically connected to an output port of the optical fiber coupler 2 using a single-mode optical fiber, allowing the optical signal output from the optical fiber coupler 2 to enter the optical fiber interface 51. This connection ensures that the light maintains single-mode propagation characteristics during transmission, avoiding interference signal degradation caused by multi-mode transmission. The output end of the optical fiber interface 51 is fixedly connected to the optical fiber interface 51 configured at the front end of the collimating lens assembly 52 through a fiber fusion splicing process.

[0085] Specifically, after the end faces of the two optical fibers are cut and aligned, they are heated by high-voltage discharge in a fusion splicer to soften the end materials and fuse them together, forming a permanent connection with low loss and high mechanical strength. Through the above-mentioned connection structure, the optical signal from the optical fiber coupler 2 can be stably transmitted to the interior of the collimating lens group 52 through the optical fiber interface 51 and the fusion point in sequence, providing an input basis for subsequent collimation optical processing.

[0086] This embodiment also provides a computer device, which is suitable for the case based on the OCT spectroscopic frequency doubling method, including: a memory and a processor; the memory is used to store computer-executable instructions, and the processor is used to execute the computer-executable instructions to implement the OCT spectroscopic frequency doubling method proposed in the above embodiment.

[0087] The computer device may be a terminal, comprising a processor, a memory, a communication interface, a display screen and an input device connected via a system bus. The processor of the computer device is used to provide computing and control capabilities. The memory of the computer device comprises a non-volatile storage medium and an internal memory. The non-volatile storage medium stores an operating system and a computer program. The internal memory provides an environment for the operation of the operating system and the computer program in the non-volatile storage medium. The communication interface of the computer device is used to communicate with an external terminal in a wired or wireless manner, and the wireless manner may be achieved through WIFI, an operator network, NFC (near field communication) or other technologies. The display screen of the computer device may be a liquid crystal display or an electronic ink display screen, and the input device of the computer device may be a touch layer covering the display screen, or a button, trackball or touchpad provided on the housing of the computer device, or an external keyboard, touchpad or mouse.

[0088] This embodiment also provides a storage medium having a computer program stored thereon, which, when executed by a processor, implements the OCT spectroscopic frequency doubling method proposed in the above embodiment; the storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disk or optical disk.

[0089] In summary, the present invention dynamically distributes interference light to multiple detector channels through a spectroscopic element, thereby realizing efficient multiplexing of the optical path. Through the three modes of spectroscopic, optical switch switching and scanning spectroscopic, it can flexibly adapt to different sampling rates and resolution requirements under the control of the main control card, and can select the optimal spectroscopic strategy according to the characteristics of the object to be measured, thereby improving the utilization rate of the interference signal and reducing optical crosstalk. By sending trigger signals with a phase difference of T / n to multiple detectors, the staggered exposure of each channel is accurately controlled to form complementary sampling windows in the time domain. Combined with the timestamp synchronization alignment and optical parameter difference compensation algorithm, the timing jitter of multi-channel acquisition and the difference in optical path transmission are eliminated, ensuring that the interference signal after frequency doubling sampling remains consistent in the time-space dimension, and ultimately achieving high-fidelity axial scanning signal reconstruction.

[0090] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A method based on OCT spectroscopic frequency doubling, characterized by: include, The light beam emitted by the light source (1) is divided into a first light path and a second light path through an optical fiber coupler (2). The first light path is transmitted to the collimating lens group (52) through the optical fiber interface (51) of the scanning detection part, passes through the two-dimensional scanning part (53), and scans the object to be measured (8) through the focusing lens (54); The second light path enters the reference arm component, passes through the polarization adjuster (41) and the reference arm collimator lens group (42) in sequence, and is then reflected by the reference arm reflector group (43); The first light path and the second light path interfere with each other in the optical fiber coupler (2), generating interference light which then enters the light splitting detection component; Performing optical mode processing on the interference light through a light splitting element (32); The continuous spectrum is divided into multiple paths by a dichroic mirror / polarization beam splitter / beam splitter prism to form a spectral splitting mode; The optical paths are alternately distributed by a light splitting element (32) to form an optical switch mode; Dynamically distribute the light path through the galvanometer / MEMS / DMD / LCOS components to form a scanning spectroscopic mode; The spectral spectrometry mode, the optical switch switching mode and the scanning spectrometry mode enter the detector 1 (33) channel, the detector 2 (34) channel and the detector 3 (35) channel respectively.

2. The OCT-based frequency doubling method according to claim 1, characterized in that: The signal processing host (6) sends phase difference T, n timing signals to the trigger pins of detector 1 (33), detector 2 (34) and detector 3 (35) by controlling the main control card (7); Where n is the number of detectors and T is the detector sampling period.

3. The OCT-based frequency doubling method according to claim 2, characterized in that: The staggered exposure of the detector array is controlled by the phase-difference T and n timing signals, so that detector 1 (33), detector 2 (34) and detector 3 (35) form complementary sampling windows in the time domain, thereby doubling the total sampling frequency.

4. The OCT-based frequency doubling method according to claim 3, characterized in that: The signal processing host (6) performs time stamp synchronization alignment processing on detector 1 (33), detector 2 (34) and detector 3 (35) by controlling the main control card (7), regards the data of different detectors as data collected by the same detector at different times, executes the optical parameter difference compensation algorithm, corrects the transmission loss of the split light path, performs interference signal splicing and reconstruction, and generates a complete axial scanning signal.

5. An OCT-based spectroscopic frequency doubling measurement system, based on the OCT-based spectroscopic frequency doubling method according to any one of claims 1 to 4, characterized in that: It includes a light source (1), an optical fiber coupler (2), a signal processing host (6), a reference arm component, a scanning detection component and an object to be measured (7); The detector lens assembly (31) includes a light splitting element (32), a detector 1 (33), a detector 2 (34) and a detector 3 (35); The reference arm component includes a polarization adjuster (41), a collimating lens group (52) and a reflecting mirror group; The scanning detection component comprises an optical fiber interface (51), a collimating lens group (52), a two-dimensional scanning part (53), and a focusing lens (54).

6. The OCT-based frequency doubling method according to claim 5, characterized in that: The input end of the detector mirror group (31) is connected to the common end of the optical fiber coupler (2) through an optical fiber, and the output end of the detector mirror group (31) maintains a conjugate relationship with the optical incident surface of the light splitting element (32).

7. The OCT-based frequency doubling method according to claim 6, characterized in that: The input end of the polarization adjuster (41) is connected to the output end of the optical fiber coupler (2) via a single-mode optical fiber, and the output end of the polarization adjuster (41) is fused with the optical fiber interface (51) of the collimating lens group (52).

8. The OCT-based frequency doubling method according to claim 7, characterized in that: The input end of the optical fiber interface (51) is connected to the output end of the optical fiber coupler (2) via a single-mode optical fiber, and the output end of the optical fiber interface (51) is fused with the optical fiber interface (51) of the collimating lens group (52).

9. A computer device comprising a memory and a processor, wherein the memory stores a computer program, wherein: When the processor executes the computer program, the steps of the OCT-based frequency doubling method according to any one of claims 1 to 7 are implemented.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the OCT-based frequency doubling method according to any one of claims 1 to 4 are implemented.

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