Vector flow velocity measuring device and method based on bidirectional scanning spectral domain optical coherence tomography technology

Abstract

The invention discloses a vector flow velocity measuring device and method based on a bidirectional scanning spectral domain optical coherence tomography technology. Comprising a super light-emitting diode light source, an optical fiber coupler, a polarization controller, an interferometer comprising a sample arm and a reference arm, and a collimating lens, the collimating lens, the grating, the focusing lens group and the linear array camera are sequentially connected through a light path; the linear array camera, the computer and the two-dimensional galvanometer are sequentially connected through a line; according to the method, the fixed bias vector velocity is introduced by utilizing the bidirectional scanning technology, the dynamic light scattering optical coherence tomography method and the Doppler optical coherence tomography method are combined, decoupling of each parameter of the vector flow velocity is efficiently and accurately realized, and a quantitative index is provided for vector flow velocity analysis. The vector flow velocity measuring device based on the bidirectional scanning spectral domain optical coherence tomography technology is simple in system setting and low in cost, the time resolution is improved by about 2.5 times, and the measuring time is shorter.

Description

Technical Field

[0001] This invention belongs to the field of vector velocity measurement technology, specifically designing a vector velocity measurement device and method based on bidirectional scanning spectral domain optical coherence tomography technology. Background Technology

[0002] Vector velocity measurements are in high demand in numerous basic research and biomedical applications to characterize complex flow fields and elucidate physiological and pathological mechanisms related to fluid dynamics.

[0003] Currently, optical methods for measuring vector flow velocity include laser Doppler blood flow measurement, laser speckle velocimetry, particle image velocimetry, Doppler optical coherence tomography, and dynamic light scattering optical coherence tomography.

[0004] In laser Doppler flow measurement, flow velocity is estimated based on the Doppler frequency shift effect between the scattered light from moving particles and the reference light. When a laser beam illuminates a scattering particle in flow, the frequency of the scattered light shifts relative to the original frequency, and this shift is proportional to the particle's flow velocity. By detecting this frequency shift signal using techniques such as optical heterodyne, vector flow velocity measurement can be achieved.

[0005] In laser speckle velocimetry, when a coherent laser beam illuminates flowing scattering particles, the reflected or transmitted light interferes in space to form a random speckle pattern. This speckle pattern fluctuates over time as the scattering particle moves. By analyzing the spatiotemporal cross-correlation function between a sequence of speckle images, the vector velocity within the field of view can be reconstructed.

[0006] In particle image velocimetry, tracer particles are implanted into the flow field to be measured, and the plane to be measured is illuminated by a pulsed laser sheet. Two or more frames of particle images are captured continuously by a high-speed camera, and the displacement of the particle image spots within a short time interval is analyzed using a cross-correlation algorithm to calculate the vector velocity of each point in the field of view.

[0007] Because optical measurement techniques such as laser Doppler flow measurement, laser speckle velocimetry, and particle image velocimetry lack depth resolution, they cannot accurately and completely assess the vector flow velocity in deep regions.

[0008] Doppler optical coherence tomography and dynamic light scattering optical coherence tomography can acquire dynamic information of scattered signals within a depth range of 1-3 mm through low coherence interference techniques, thus enabling a complete characterization of vector flow velocity along the depth direction.

[0009] In Doppler optical coherence tomography (OCT), optical coherence tomography is combined with the Doppler principle to measure flow velocity by analyzing the change in the phase of scattered light over time. The movement of scattering particles in the fluid causes a shift in the phase of the scattered light, and this shift is proportional to the particle's flow velocity. By scanning point by point and detecting the phase difference between adjacent measurement points, the flow velocity distribution along the beam direction can be reconstructed. However, this method depends on the Doppler angle and lacks sensitivity to flow velocities in directions orthogonal to the measurement beam. Multi-beam Doppler OCT can be used to determine vector flow velocities, but it requires additional detection equipment, increasing system complexity.

[0010] In dynamic light scattering optical coherence tomography (OCT), the time autocorrelation function is calculated to reflect the motion characteristics of scattering particles by utilizing the intensity or phase fluctuations of the scattered signal over time. When scattering particles move randomly or flow in the fluid, the signal correlation gradually decays. The phase change rate of the correlation function is proportional to the axial flow velocity, while the decay rate reflects the velocity of diffusion and lateral motion, but usually cannot distinguish direction. To quantify the vector lateral velocity, a variable scan bias velocity can be introduced into the system to extract the vector lateral velocity based on dynamic light scattering OCT. However, this method requires finding the optimal scan point matching the fluid flow through a series of scan bias velocities, resulting in long acquisition times and low computational efficiency. Summary of the Invention

[0011] This invention aims to at least partially solve one of the technical problems in related technologies, and provides a vector flow velocity measurement device and method based on bidirectional scanning spectral domain optical coherence tomography technology. This invention is achieved through the following technical solution:

[0012] This invention discloses a device for measuring vector flow velocity based on bidirectional scanning spectral domain optical coherence tomography (OCT). The device comprises, in sequence, an ultra-light-emitting diode (LED) light source, an optical fiber coupler, a polarization controller, an interferometer including a sample arm and a reference arm, and a collimating lens; in sequence, a collimating lens, a grating, a focusing lens group, and a linear array camera; in sequence, a linear array camera, a computer for emitting signals, acquiring data, and processing data, and a two-dimensional galvanometer; the reference arm includes a collimator A, a focusing lens A, and a plane mirror in sequence; and the sample arm includes a collimator B, a two-dimensional galvanometer, a focusing lens B, and a sample in sequence.

[0013] As a further improvement, the two-dimensional galvanometer described in this invention is connected to a computer and serves as the line input terminal of the sample arm for realizing forward and reverse scanning.

[0014] As a further improvement, the device for measuring vector flow velocity using bidirectional scanning spectral domain optical coherence tomography technology described in this invention includes:

[0015] The light emitted by the superluminescent diode light source is split into two beams by an optical fiber coupler. One beam passes through the collimator of the sample arm, the two-dimensional galvanometer, and the focusing lens B to illuminate the flow sample to be tested; the other beam passes through the polarization controller, the collimator of the reference arm, and the focusing lens A to illuminate the plane mirror.

[0016] The light returning from the sample arm and the reference arm interferes within the optical coupler. The interfering light enters the collimating lens from the fiber optic port, is collimated, and then split by the grating. The focusing lens group focuses the split beam onto the photosensitive surface of the linear array camera.

[0017] The forward and reverse scanning of the sample arm beam is achieved by using a two-dimensional galvanometer. The forward and reverse scanning interference light signals of the sample changing over time are acquired by a computer. The interference light signals are referred to as light signals below.

[0018] Calculate the autocorrelation coefficients of the forward and reverse scanning light signal intensities at different delay times, and calculate the axial flow velocity measured by Doppler optical coherence tomography.

[0019] The quadratic term coefficient of the autocorrelation coefficient with time delay is fitted, and the longitude angle, latitude angle, and absolute velocity are calculated by combining the quadratic term coefficient with the axial velocity measured by Doppler optical coherence tomography, thereby determining the vector velocity.

[0020] As a further improvement, the present invention specifically describes the acquisition of forward and reverse scanning interference light signals of the sample over time by computer: a triangular wave driving signal is emitted by the computer to cause the two-dimensional galvanometer to generate scanning bias speeds of the same magnitude but opposite directions to achieve bidirectional scanning, and the bidirectional scanning light signals of the sample under test over time within the same spatial range are acquired by the computer.

[0021] As a further improvement, the calculation of the autocorrelation coefficient of the forward scanning light signal intensity at different delay times in this invention includes: calculating the autocorrelation coefficient of the forward scanning light signal intensity at different delay times at different depths of the sample under test, setting the bidirectional scanning direction as the X-axis, and at depth z, the normalized autocorrelation function satisfied by the autocorrelation coefficient of the forward scanning light signal intensity at different delay times is:

[0022] ;

[0023] in, The intensity of the forward scanning light signal at depth z in the time delay The autocorrelation coefficient under the following conditions The intensity of the reverse scanning optical signal at depth z in time delay The autocorrelation coefficients under the following conditions, where Let be the refractive index of the medium. The central wave number, The diffusion coefficient is the flow field diffusion coefficient. To delay time, The depth direction of the sample to be tested. For depth The lateral velocity below, For depth The axial velocity below, To introduce lateral scan bias speed, The horizontal beam waist, For the coherent length waist, For depth The longitude angle below.

[0024] As a further improvement, the calculation of the autocorrelation coefficient of the reverse scanning optical signal intensity at different delay times in this invention includes: calculating the autocorrelation coefficient of the reverse scanning optical signal intensity at different delay times at different depths of the sample under test, setting the bidirectional scanning direction as the X-axis, and at depth z, the normalized autocorrelation function satisfied by the autocorrelation coefficient of the reverse scanning optical signal intensity at different delay times is:

[0025]

[0026] As a further improvement, the quadratic term coefficient of the fitting autocorrelation coefficient with time delay described in this invention is used to calculate the longitude angle, latitude angle, and absolute velocity by combining the quadratic term coefficient with the axial velocity measured by Doppler optical coherence tomography, thereby determining the vector velocity.

[0027] As a further improvement, the sample to be tested in this invention is a particle dispersion system that can generate dynamic light scattering signals, wherein the particles are polystyrene microspheres or materials with appropriate light scattering properties.

[0028] As a further improvement, the material with appropriate light scattering properties described in this invention is any one of latex microparticles, silica microspheres, metal nanoparticles, biological cells, extracellular vesicles, liposomes, and biological tissue phantoms.

[0029] Based on the above technical solution, the beneficial effects of the present invention compared with the prior art are as follows:

[0030] 1. Compared with existing technologies, this invention utilizes bidirectional scanning technology to introduce a fixed bias vector velocity, and combines dynamic light scattering optical coherence tomography and Doppler optical coherence tomography to efficiently and accurately decouple the parameters of vector velocity, providing quantitative indicators for vector velocity analysis.

[0031] 2. Compared with existing vector velocity measurement methods using multi-beam Doppler optical coherence tomography, the vector velocity measurement device system based on bidirectional scanning spectral domain optical coherence tomography technology provided by this invention has a simple setup and low cost: it can directly perform vector velocity measurement with only a spectral domain optical coherence tomography system with a bidirectional scanning galvanometer, without the need for additional complex devices.

[0032] 3. Compared with the existing vector velocity measurement method of multi-beam Doppler optical coherence tomography, the measurement provided by this invention can directly solve for the vector velocity without relying on the Doppler angle, and the velocity measurement range is increased by about 15 times.

[0033] 4. Compared with existing vector velocity measurement methods based on dynamic light scattering optical coherence tomography using variable scanning bias velocity, the measurement method provided by this invention has high computational efficiency: The vector velocity measurement method based on bidirectional scanning spectral domain optical coherence tomography proposed in this invention has a simple data acquisition and processing process, requiring no multiple changes in the scanning bias velocity. Only one bidirectional scanning optical signal acquisition along the X and Y directions is needed to directly solve for the various parameters of the vector velocity. The temporal resolution of this invention is improved by approximately 2.5 times, and the measurement time is shorter. Attached Figure Description

[0034] Figure 1 is a system diagram of a vector flow velocity measurement device based on bidirectional scanning spectral domain optical coherence tomography technology according to an embodiment of the present invention;

[0035] Figure 2 This is a schematic diagram of a vector velocity analysis process according to an embodiment of the present invention;

[0036] Figure 3 is a schematic diagram of bidirectional scanning of the present invention and a schematic diagram of the spatial geometric relationship of various parameters used to characterize the vector flow field, including lateral velocity, axial velocity, absolute velocity, longitude angle, and latitude angle.

[0037] Figure 4 is a B-mode optical coherence tomography image of forward and reverse scanning according to an embodiment of the present invention;

[0038] Figure 5 is a schematic diagram of the autocorrelation coefficients of forward and reverse scanning as a function of delay time according to an embodiment of the present invention;

[0039] Figure 6 is a schematic diagram showing the variation of the quadratic term coefficients of forward and reverse scanning with depth according to an embodiment of the present invention;

[0040] Figure 7 is a schematic diagram showing the variation of various parameters of the vector flow velocity with depth according to an embodiment of the present invention;

[0041] Figure 1In the middle: 1. Superluminescent diode light source, 2. Fiber optic coupler, 3. Polarization controller, 4. Collimator A, 5. Focusing lens A, 6. Plane mirror, 7. Collimator B, 8. Two-position galvanometer, 9. Focusing lens B, 10. Sample, 11. Collimating lens, 12. Grating, 13. Focusing lens group, 14. Linear scan camera, 15. Computer. Detailed Implementation

[0042] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0043] Figure 1 is a system diagram of a vector flow velocity measurement device based on bidirectional scanning spectral domain optical coherence tomography (OCT) technology according to the present invention. The vector flow velocity measurement device based on bidirectional scanning spectral domain OCT technology includes: a superluminescent diode light source 1, an optical fiber coupler 2, a polarization controller 3, an interferometer including a sample arm and a reference arm, and a collimating lens 11, all connected in sequence by optical fibers; a collimating lens 11, a grating 12, a focusing lens group 13, and a linear array camera 14, all connected in sequence by optical paths; a linear array camera 14, a computer 15 for emitting signals, acquiring data, and processing data, and a two-dimensional galvanometer 8, all connected in sequence by optical paths; the reference arm includes a collimator A4, a focusing lens A5, and a plane mirror 6, all connected in sequence by optical paths; the sample arm includes a collimator B7, a two-dimensional galvanometer 8, a focusing lens B9, and a sample 10, all connected in sequence by optical paths.

[0044] Computer 15 sends a triangular wave drive signal to cause the two-dimensional galvanometer 8 to generate scanning bias speeds of the same magnitude but opposite directions to achieve bidirectional scanning. Computer 15 also collects the bidirectional scanning light signal of the sample 10 under test as it changes over time within the same scanning range.

[0045] Sample 10 is placed at the defocus position of its front focusing lens B9 to ensure that the particle probability distribution and scattered light fluctuation characteristics within the scattering volume both satisfy Gaussian statistical laws.

[0046] The effective bidirectional scanning range of the two-dimensional galvanometer 8 must be consistent with the imaging area of ​​the sample 10.

[0047] Figure 2 is a flowchart of a method for measuring vector flow velocity based on bidirectional scanning spectral domain optical coherence tomography (OCT) of the present invention; the present invention also discloses a method for measuring vector flow velocity based on bidirectional scanning spectral domain OCT, the specific steps of which include:

[0048] Light emitted from a superluminescent diode light source 1 is split into two beams by an optical fiber coupler 2. One beam passes through a collimator in the sample arm, a two-dimensional galvanometer 8, and a focusing lens B9 to illuminate the flow sample 10 under test. The other beam passes through a polarization controller 3, a collimator in the reference arm, and a focusing lens A5 to illuminate a plane mirror 6. The light returning from the sample arm and the reference arm interferes within the optical fiber coupler. The interference light enters the collimating lens 11 from the fiber optic port, is collimated, and then split by a grating 12. The focusing lens group 13 focuses the split beam onto the photosensitive surface of a linear array camera 14. The two-dimensional galvanometer 8 enables forward and reverse scanning of the sample arm beam. A computer 15 collects the forward and reverse scanning interference light signals of the sample 10 over time. The interference light signals are referred to as optical signals below.

[0049] The autocorrelation coefficients of the forward and reverse scanning light signal intensities at different delay times are calculated, and the axial flow velocity measured by Doppler optical coherence tomography is calculated. The autocorrelation coefficients of the bidirectional scanning light signal intensities at different delay times are also calculated, including: calculating the autocorrelation function of the forward scanning light signal intensity of the sample 10 under test at different time delays, and the autocorrelation function of the reverse scanning light signal intensity at different time delays. The bidirectional scanning light signal intensity of this invention is the light signal intensity of each depth pixel in the XZ plane that changes over time, acquired by computer 15; this signal is called the B-mode signal. This invention assumes that scattering particles within the same depth spatial range satisfy the stationarity assumption and maintain a consistent motion state; therefore, only the time dimension is considered laterally, similar to a signal changing over time at any point in space. The autocorrelation function can be understood as calculating the light signal intensity I( at depth z) acquired at different time points. , ) (i=1,...,n) and I( +τ, The Pearson correlation coefficient between signal intensity sequences (i=1,...,n) is given by I( , ) indicates that the depth z position is at Time's up The sequence of light signal intensity within this time range, I( +τ, ) indicates that the depth z position is at +τ time to The sequence of light signal intensity within the time range of time +τ, where τ represents the delay time between the two sequences. Ideally, if the scattering particles in sample 10 undergo no directional translational motion, I( , ) and I( +τ, The Pearson correlation coefficient between the signals is the largest, indicating that only diffusion motion exists. If the scattering particles in sample 10 exhibit directional translational motion, I( , ) and I( +τ, When the Pearson correlation coefficient between signals decreases, directional translational motion and diffusion motion exist. The formula for calculating the autocorrelation coefficient of the forward scanning optical signal intensity at different delay times is:

[0050] =

[0051] in, Let Z be the autocorrelation coefficient at depth z with time delay τ. This is the intensity sequence of the forward scanning light signal acquired at time t. for The sequence of forward scanning light signal intensity acquired at each time step, where τ is the delay time and z is the depth direction of the sample 10 under test. express and The covariance of the sequence, and They represent sequence sum The variance of the sequence.

[0052] Covariance and variance are calculated using the following formulas:

[0053]

[0054]

[0055]

[0056] The process of calculating the autocorrelation coefficient of the reverse scanning optical signal intensity at different delay times is exactly the same as the process described above, and will not be repeated here.

[0057] With the bidirectional scanning direction set as the X-axis, at depth z, the normalized autocorrelation function satisfied by the autocorrelation coefficient of the forward scanning light signal intensity at different delay times is:

[0058]

[0059] The normalized autocorrelation function satisfied by the autocorrelation coefficients of the reverse scanning optical signal intensity at different delay times is:

[0060]

[0061] in, The intensity of the forward scanning light signal at depth z in the time delay The autocorrelation coefficient under the following conditions The intensity of the reverse scanning optical signal at depth z in time delay The autocorrelation coefficients under the following conditions, where Let be the refractive index of the medium. The central wave number, The diffusion coefficient is the flow field diffusion coefficient. To delay time, The depth direction of the sample 10 to be tested. For depth The lateral velocity below, For depth The axial velocity below, To introduce lateral scan bias speed, The horizontal beam waist, For the coherent length waist, For depth The longitude angle below. Figure 3 is a schematic diagram of the bidirectional scanning of the present invention and , , , , A schematic diagram of the spatial geometric relationships of the parameters used to characterize the vector flow field is provided. Specifically, the sample 10 to be tested is illuminated by a light source, and the light emitted by the light source is bidirectionally scanned on the sample 10 with the same magnitude but opposite directions at the same scanning bias velocity through a galvanometer. The bidirectional scanning light signal of the sample 10 as a function of time within the same spatial range is collected. Figure 3 (a) shows the flow field and illumination beam layout of the sample arm under bidirectional scanning of the galvanometer. Figure 3 (b) shows the longitude angle in the Cartesian coordinate system. latitude angle The vector velocity is decomposed into lateral velocity. and axial velocity . Figure 3 (c) shows the bidirectional composite velocity obtained based on the parallelogram rule under the bidirectional scanning bias velocity. , The two-way synthesis speed is from and The coefficient of the quadratic term is determined by this. The axial velocity is obtained by combining the Doppler optical coherence tomography method. This allows for the decoupling of the lateral vector velocity. Figure 4The B-mode image of this invention was acquired in the XZ plane, with the X-axis considering only the time dimension and the Z-axis representing the depth direction of sample 10. It can be seen that the forward-scanning and reverse-scanning light signal intensity images differ significantly due to the difference in synthesis speed. Using this B-mode image, the autocorrelation coefficient of the bidirectional scanning light signal intensity at different depths under different delay times can be calculated. It is understood that the vector velocity measurement device based on bidirectional scanning spectral domain optical coherence tomography technology of this invention can obtain the distribution information of sample 10 at different depths in the Z-direction (beam direction) under bidirectional scanning. In terms of measuring light signals, compared to other acquisition systems, the device of this invention can obtain more dimensional information and has imaging capabilities in the depth Z-direction.

[0062] The axial flow velocity measured by Doppler optical coherence tomography is calculated as follows:

[0063]

[0064] Where Re(·) and Im(·) represent the extraction of the real and imaginary parts of the forward scanning complex optical signal, respectively. For the first Column depth is The forward scanning complex optical signal at the location. This represents the time interval between adjacent columns. J and N represent the number of pixels used for window averaging in the horizontal and axial directions, respectively. Here, J=N=4.

[0065] The quadratic term coefficient of the autocorrelation coefficient with time delay is fitted, and the longitude angle, latitude angle, and absolute velocity are calculated by combining the quadratic term coefficient with the axial velocity measured by Doppler optical coherence tomography, thereby determining the vector velocity.

[0066] The quadratic coefficients of the fitted autocorrelation coefficients with time delay include: the quadratic coefficients of the fitted normalized autocorrelation function for the forward scan and the quadratic coefficients of the fitted normalized autocorrelation function for the reverse scan. Let the transverse waist calibration coefficient... Let the axial waist calibration coefficient The quadratic coefficient of the normalized autocorrelation function for forward scanning is:

[0067]

[0068] The quadratic coefficient of the normalized autocorrelation function for reverse scanning is:

[0069]

[0070] For the lateral waist adjustment coefficient, This is the axial waist calibration coefficient. The sample 10 is set to a non-flowing state and subjected to the same known bias velocity. right and By fitting the coefficients of the quadratic term, the transverse calibration coefficients can be obtained. . Determined by the bandwidth and center wavelength of the light source, the sample to be tested 10 is set as the plane mirror 6. The axial point spread function decays to 1 / e 2 The length of the waist at that time. Figure 5 This image shows the autocorrelation coefficients of the bidirectional scanning optical signal intensity at different delay times and the corresponding fitting curves. The image illustrates the autocorrelation coefficients of the bidirectional scanning optical signal intensity at a specific depth location at different delay times. The quadratic coefficient of the normalized autocorrelation function is obtained through the fitting curves. Figure 6 This is a scatter plot of the quadratic coefficients of the normalized autocorrelation function of the bidirectional scanning method of this invention at different depths.

[0071] The vector velocity is determined by calculating the longitude angle, latitude angle, and absolute velocity by combining the quadratic coefficients of the normalized autocorrelation function with the axial velocity measured by Doppler optical coherence tomography. This includes: [The text abruptly ends here, likely due to an incomplete sentence or missing information.] , , Solving for the problem yields:

[0072]

[0073]

[0074]

[0075]

[0076] in For depth Latitude angle below, For depth The absolute flow velocity at this point. Within the range (0,π), to fully analyze the interval (0, 2π), an additional bidirectional scan is performed along the Y-axis to obtain the quadratic coefficients of the normalized autocorrelation function for the bidirectional scan along the Y-axis. By comparing the magnitudes of the quadratic coefficients of the normalized autocorrelation function for the bidirectional scan along the X-axis and the Y-axis, the final determination is... The quadrant. Figure 7The vector flow velocity calculated by this invention under a standard cylindrical pipe with an inner diameter of 1 mm includes the change of absolute flow velocity with depth. It exhibits a typical Poisson's parabolic flow surface and basically matches the theoretical value. The measured values ​​of longitude and latitude angles also basically match the theoretical values.

[0077] In this invention, the forward and reverse scanning of the sample arm beam is achieved by a two-dimensional galvanometer 8. The driving signals for the forward and reverse scanning are triangular waves issued by a computer 15.

[0078] In this invention, the sample 10 to be tested is a particulate dispersion system capable of generating dynamic light scattering signals. The particles are polystyrene microspheres or materials with appropriate light scattering properties. Materials with appropriate light scattering properties are any one of latex microparticles, silica microspheres, metal nanoparticles, biological cells, extracellular vesicles, liposomes, and biomimetic tissues.

[0079] The above are merely preferred embodiments of the present invention. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make many possible variations and modifications to the technical solutions of the present invention using the methods and techniques disclosed above, or modify them into equivalent embodiments with equivalent changes, without departing from the scope of the technical solutions of the present invention. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solutions of the present invention shall still fall within the protection scope of the technical solutions of the present invention.

Claims

1. A device for measuring vector flow velocity based on bidirectional scanning spectral domain optical coherence tomography, characterized in that, The system includes, in sequence, an ultra-light-emitting diode (LED) light source, an optical fiber coupler, a polarization controller, an interferometer including a sample arm and a reference arm, and a collimating lens; in sequence, a collimating lens, a grating, a focusing lens group, and a linear array camera; in sequence, a linear array camera, a computer for emitting signals, acquiring data, and processing data, and a two-dimensional galvanometer; the reference arm includes a collimator A, a focusing lens A, and a plane mirror in sequence; the sample arm includes a collimator B, a two-dimensional galvanometer, a focusing lens B, and a sample in sequence.

2. The apparatus for measuring vector flow velocity based on bidirectional scanning spectral domain optical coherence tomography as described in claim 1, characterized in that, The two-dimensional galvanometer is connected to a computer and serves as the line input terminal of the sample arm for forward and reverse scanning.

3. A method for measuring vector flow velocity based on bidirectional scanning spectral domain optical coherence tomography, characterized in that, This is achieved through a device for measuring vector flow velocity based on bidirectional scanning spectral domain optical coherence tomography, including: The light emitted by the superluminescent diode light source is split into two beams by an optical fiber coupler. One beam passes through the collimator of the sample arm, the two-dimensional galvanometer, and the focusing lens B to illuminate the flow sample to be tested; the other beam passes through the polarization controller, the collimator of the reference arm, and the focusing lens A to illuminate the plane mirror. The light returning from the sample arm and the reference arm interferes within the optical coupler. The interfering light enters the collimating lens from the fiber optic port, is collimated, and then split by the grating. The focusing lens group focuses the split beam onto the photosensitive surface of the linear array camera. The two-dimensional galvanometer is used to achieve forward and reverse scanning of the sample arm beam. The forward and reverse scanning interference light signals of the sample as a function of time are collected by a computer. The interference light signals are referred to as light signals below. Calculate the autocorrelation coefficients of the forward scanning light signal intensity and the reverse scanning light signal intensity at different delay times, and calculate the axial flow velocity measured by Doppler optical coherence tomography. The quadratic term coefficient of the autocorrelation coefficient is fitted with time delay. The longitude angle, latitude angle, and absolute velocity are calculated by combining the quadratic term coefficient with the axial velocity measured by Doppler optical coherence tomography, thereby determining the vector velocity.

4. The method for measuring vector flow velocity according to claim 3, characterized in that, The method of acquiring the forward and reverse scanning interference light signals of the sample over time via computer specifically involves: the computer emitting a triangular wave drive signal to cause the two-dimensional galvanometer to generate scanning bias speeds of the same magnitude but opposite directions to achieve bidirectional scanning; and the computer acquiring the bidirectional scanning light signals of the sample under test over time within the same spatial range.

5. The method according to claim 3, characterized in that, The calculation of the autocorrelation coefficient of the forward scanning optical signal intensity at different delay times includes: calculating the autocorrelation coefficient of the forward scanning optical signal intensity at different delay times at different depths of the sample under test, setting the bidirectional scanning direction as the X-axis, and at depth z, the normalized autocorrelation function satisfied by the autocorrelation coefficient of the forward scanning optical signal intensity at different delay times is: ； in, The intensity of the forward scanning light signal at depth z in the time delay The autocorrelation coefficient under the following conditions The intensity of the reverse scanning optical signal at depth z in time delay The autocorrelation coefficients under the following conditions, where Let be the refractive index of the medium. The central wave number, The diffusion coefficient is the flow field diffusion coefficient. To delay time, The depth direction of the sample to be tested. For depth The lateral velocity below, For depth The axial velocity below, To introduce lateral scan bias speed, The horizontal beam waist, For the coherent length waist, For depth The longitude angle below.

6. The method according to claim 3, characterized in that, The calculation of the autocorrelation coefficient of the reverse scanning optical signal intensity at different delay times includes: calculating the autocorrelation coefficient of the reverse scanning optical signal intensity at different delay times at different depths of the sample under test, setting the bidirectional scanning direction as the X-axis, and at depth z, the normalized autocorrelation function satisfied by the autocorrelation coefficient of the reverse scanning optical signal intensity at different delay times is:

7. The method according to claim 3, 4, 5, or 6, characterized in that, The fitting of the autocorrelation coefficient with time delay quadratic term coefficients, combined with the axial flow velocity measured by Doppler optical coherence tomography, yields the longitude angle, latitude angle, and absolute flow velocity, thereby determining the vector flow velocity.

8. The method according to claim 7, characterized in that, The sample to be tested is a particle dispersion system capable of generating dynamic light scattering signals, wherein the particles are polystyrene microspheres or materials with appropriate light scattering properties.

9. The method according to claim 8, characterized in that, The material with appropriate light scattering properties is any one of latex microparticles, silica microspheres, metal nanoparticles, biological cells, extracellular vesicles, liposomes, and biological tissue phantoms.

Images