OCT imaging method

Abstract

The application provides an OCT imaging method, and relates to the technical field of data processing. The method comprises the following steps: acquiring first sweep frequency data corresponding to a first sweep frequency stage and second sweep frequency data corresponding to a second sweep frequency stage in one sweep frequency cycle, the sweep frequency directions of the first sweep frequency stage and the second sweep frequency stage being opposite; performing phase correction processing on the first sweep frequency data to obtain first sweep frequency data after phase correction processing, and determining third sweep frequency data and fourth sweep frequency data according to the second sweep frequency data and the first sweep frequency data after phase correction processing; and determining an OCT image based on the third sweep frequency data and the fourth sweep frequency data. The method can adapt to a bidirectional sweep frequency mode.

Description

Technical Field

[0001] This application relates to the field of data processing technology, and in particular to an OCT imaging method. Background Technology

[0002] In swept-source optical coherence tomography (SS-OCT), the sweep rate and imaging efficiency of the swept-source (SS) are key factors determining system performance. In recent years, bidirectional sweep mode has received widespread attention to improve the duty cycle and imaging speed of the swept-source. In bidirectional swept-source OCT, the source sequentially completes two wavelength scans within one sweep cycle: forward (e.g., from short wavelength to long wavelength) and reverse (e.g., from long wavelength to short wavelength), achieving an equivalent A-scan imaging rate increase of approximately one time.

[0003] Most existing OCT imaging methods are designed for unidirectional frequency sweep mode and are not suitable for bidirectional frequency sweep mode. Therefore, there is an urgent need for an OCT imaging method that can be adapted to bidirectional frequency sweep mode. Summary of the Invention

[0004] Therefore, it is necessary to provide an OCT imaging method adapted to bidirectional frequency sweep mode to address the aforementioned technical problems.

[0005] This application provides an OCT imaging method, including:

[0006] Obtain the first frequency sweep data corresponding to the first frequency sweep stage and the second frequency sweep data corresponding to the second frequency sweep stage within a frequency sweep cycle. The frequency sweep directions of the first frequency sweep stage and the second frequency sweep stage are opposite.

[0007] The first frequency sweep data is subjected to phase correction processing to obtain the phase-corrected first frequency sweep data, and the third and fourth frequency sweep data are determined based on the second frequency sweep data and the phase-corrected first frequency sweep data.

[0008] The OCT image is determined based on the third and fourth frequency sweep data.

[0009] In one embodiment, phase correction processing is performed on the first sweep frequency data to obtain phase-corrected first sweep frequency data, including: shifting the phase of the first sweep frequency data along the wavenumber axis to obtain phase-corrected first sweep frequency data.

[0010] In one embodiment, the phase of the first frequency sweep data is shifted along the wavenumber axis to obtain the first frequency sweep data after phase correction. This includes: determining the shift amount based on the first-order dispersion coefficient and the second-order dispersion coefficient, and shifting the phase of the first frequency sweep data along the wavenumber axis according to the shift amount to obtain the first frequency sweep data after phase correction. The first-order dispersion coefficient includes the first-order dispersion coefficient corresponding to the first frequency sweep stage and the first-order dispersion coefficient corresponding to the second frequency sweep stage, and the second-order dispersion coefficient includes the second-order dispersion coefficient corresponding to the first frequency sweep stage and the second-order dispersion coefficient corresponding to the second frequency sweep stage.

[0011] In one embodiment, acquiring first frequency sweep data corresponding to the first frequency sweep stage and second frequency sweep data corresponding to the second frequency sweep stage within a frequency sweep cycle includes: acquiring original first frequency sweep data and original second frequency sweep data collected by the OCT device in one frequency sweep cycle; the original first frequency sweep data is the frequency sweep data collected by the OCT device in the first frequency sweep stage, and the original second frequency sweep data is the frequency sweep data collected by the OCT device in the second frequency sweep stage; and resampling the original first frequency sweep data and the original second frequency sweep data to obtain the first frequency sweep data and the second frequency sweep data.

[0012] In one embodiment, resampling is performed on the original first frequency sweep data and the original second frequency sweep data to obtain the first frequency sweep data and the second frequency sweep data. This includes: obtaining a first resampling phase range corresponding to the first frequency sweep stage and a second resampling phase range corresponding to the second frequency sweep stage; determining an overlapping resampling phase range based on the first resampling phase range and the second resampling phase range; and resampling the original first frequency sweep data and the original second frequency sweep data using the overlapping resampling phase range to obtain the first frequency sweep data and the second frequency sweep data.

[0013] In one embodiment, the method further includes: acquiring the first rising edge and the first falling edge of a first bandpass filter that filters the clock signal corresponding to the first frequency sweep stage, and acquiring the second rising edge and the second falling edge of a second bandpass filter that filters the clock signal corresponding to the second frequency sweep stage; determining a target rising edge based on the first rising edge and the second rising edge, and determining a target falling edge based on the first falling edge and the second falling edge; and resampling the original first frequency sweep data and the original second frequency sweep data based on the target rising edge and the target falling edge to obtain the first frequency sweep data and the second frequency sweep data.

[0014] In one embodiment, determining the third and fourth frequency sweep data based on the second frequency sweep data and the first frequency sweep data after phase correction processing includes: obtaining the first dispersion compensation coefficient corresponding to the first frequency sweep stage and the second dispersion compensation coefficient corresponding to the second frequency sweep stage, and averaging the first and second dispersion compensation coefficients to determine the target dispersion compensation coefficient; using the target dispersion compensation coefficient, performing dispersion compensation processing on the second frequency sweep data and the first frequency sweep data after phase correction processing to obtain the first frequency sweep data and the second frequency sweep data after dispersion compensation processing; and determining the third and fourth frequency sweep data based on the first frequency sweep data and the second frequency sweep data after dispersion compensation processing.

[0015] In one embodiment, the first dispersion compensation coefficient includes the second-order dispersion coefficient and the third-order dispersion coefficient corresponding to the first frequency sweep stage; the second dispersion compensation coefficient includes the second-order dispersion coefficient and the third-order dispersion coefficient corresponding to the second frequency sweep stage.

[0016] In one embodiment, the method further includes: flipping the first sweep frequency data / second sweep frequency data along the wavenumber axis, and performing phase correction processing on the first sweep frequency data after the flipping processing to obtain the phase-corrected first sweep frequency data; or, flipping the third sweep frequency data / fourth sweep frequency data along the wavenumber axis, and determining the OCT image based on the third sweep frequency data and the fourth sweep frequency data after the flipping processing.

[0017] In one embodiment, determining an OCT image based on third and fourth frequency sweep data includes: determining an initial B-scan image based on the third and fourth frequency sweep data; acquiring multiple first A-scans and multiple second A-scans from the initial B-scan image; wherein the first A-scans are obtained based on the third frequency sweep data and the second A-scans are obtained based on the fourth frequency sweep data; determining an offset based on the multiple first A-scans and multiple second A-scans; and performing correction processing on the initial B-scan image according to the offset to obtain an OCT image.

[0018] The aforementioned OCT imaging method first acquires first sweep data corresponding to the first sweep stage and second sweep data corresponding to the second sweep stage within a sweep cycle, with the sweep directions of the first and second sweep stages being opposite. Then, phase correction processing is performed on the first sweep data to obtain phase-corrected first sweep data. Third and fourth sweep data are determined based on the second sweep data and the phase-corrected first sweep data. Finally, an OCT image is determined based on the third and fourth sweep data. The OCT imaging method provided in this application, by performing phase correction processing on the sweep data of one sweep stage within a sweep cycle, achieves phase matching of the sweep data in both directions within a sweep cycle in the frequency domain. Then, an OCT image is determined based on the phase-corrected sweep data. This solves the problem that traditional OCT imaging methods are only applicable to unidirectional sweeps and cannot be compatible with bidirectional sweeps, thus realizing OCT imaging in bidirectional sweep mode. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this application or related technologies, the drawings used in the description of the embodiments of this application or related technologies will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a flowchart illustrating an OCT imaging method in one embodiment;

[0021] Figure 2 This is a flowchart illustrating a method for obtaining first frequency sweep data corresponding to the first frequency sweep stage and second frequency sweep data corresponding to the second frequency sweep stage within a frequency sweep cycle, as shown in one embodiment.

[0022] Figure 3 This is a flowchart illustrating a method for obtaining first and second frequency sweep data in one embodiment.

[0023] Figure 4 This is a flowchart illustrating a method for obtaining first and second frequency sweep data in another embodiment;

[0024] Figure 5 This is a flowchart illustrating a method for determining the third and fourth frequency sweep data in one embodiment;

[0025] Figure 6 This is a schematic diagram of the signal intensity curves of the first and second frequency sweep data corresponding to the A-scan before dispersion compensation processing in one embodiment.

[0026] Figure 7This is a schematic diagram of the signal intensity curves of the first and second frequency sweep data corresponding to the A-scan after dispersion compensation processing in one embodiment.

[0027] Figure 8 This is a flowchart illustrating a method for determining an OCT image in one embodiment;

[0028] Figure 9 This is a schematic diagram of the initial B-scan image in one embodiment;

[0029] Figure 10 This is a schematic diagram of a B-scan image after correction processing in one embodiment;

[0030] Figure 11 for Figure 9 A magnified view of a portion of the image. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0032] It should be noted that the terms "first," "second," etc., used in this application can be used to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish the first element from the second element. The terms "comprising" and "having," and any variations thereof, used in this application, are intended to cover non-exclusive inclusion. The term "multiple" used in this application refers to two or more. The term "and / or" used in this application refers to one of the embodiments, or any combination of multiple embodiments.

[0033] In swept-source optical coherence tomography (SS-OCT), the sweep rate and imaging efficiency of the swept-source (SS) are key factors determining system performance. In recent years, bidirectional sweep mode has received widespread attention to improve the duty cycle and imaging speed of the swept-source. In bidirectional swept-source OCT, the source sequentially completes two wavelength scans within one sweep cycle: forward (e.g., from short wavelength to long wavelength) and reverse (e.g., from long wavelength to short wavelength), achieving an equivalent A-scan imaging rate increase of approximately one time.

[0034] Most existing OCT imaging methods are designed for unidirectional frequency sweep mode and are not suitable for bidirectional frequency sweep mode. Therefore, there is an urgent need for an OCT imaging method that can be adapted to bidirectional frequency sweep mode.

[0035] In view of this, this application provides an OCT imaging method. First, it acquires first sweep data corresponding to the first sweep stage and second sweep data corresponding to the second sweep stage within a sweep cycle, wherein the sweep directions of the first and second sweep stages are opposite. Then, it performs phase correction processing on the first sweep data to obtain phase-corrected first sweep data. Third and fourth sweep data are determined based on the second sweep data and the phase-corrected first sweep data. Finally, an OCT image is determined based on the third and fourth sweep data. The OCT imaging method provided in this application, by performing phase correction processing on the sweep data of one sweep stage within a sweep cycle, achieves phase matching of the sweep data in both directions within a sweep cycle in the frequency domain. Then, it determines the OCT image based on the phase-corrected sweep data, solving the problem that traditional OCT imaging methods are only applicable to unidirectional sweeps and cannot be compatible with bidirectional sweeps, thus realizing OCT imaging in bidirectional sweep mode.

[0036] The OCT imaging method provided in this application can be executed by a computer device, which can be a terminal.

[0037] In one exemplary embodiment, such as Figure 1 As shown, an OCT imaging method is provided, which includes the following steps:

[0038] Step 101: Obtain the first frequency sweep data corresponding to the first frequency sweep stage and the second frequency sweep data corresponding to the second frequency sweep stage within a frequency sweep cycle.

[0039] Optionally, the sweep cycle refers to the time required for the wavelength of the output light from the sweeping light source to complete one full periodic change. For example, a sweep cycle may include a forward sweep phase and a reverse sweep phase. The forward sweep phase refers to the continuous change of the output wavelength of the light source from its initial value to its final value, and the output wavelength of the light source exhibits a unidirectional increasing or decreasing trend during the forward sweep phase, for example, a continuous change from a short wavelength to a long wavelength. The reverse sweep phase refers to the continuous change of the output wavelength of the light source from its final value back to its initial value in preparation for the next cycle, and the output wavelength of the light source exhibits the opposite trend to that of the forward sweep phase, for example, a continuous change from a long wavelength to a short wavelength.

[0040] Optionally, the scanning directions of the first and second frequency scanning stages are opposite. The order of the first and second frequency scanning stages is not limited in this application; that is, the first frequency scanning stage can be before or after the second frequency scanning stage. For example, the first frequency scanning stage can be a forward frequency scanning stage within a frequency scanning cycle, and if the first frequency scanning stage is a forward frequency scanning stage, the second frequency scanning stage can be a reverse frequency scanning stage within a frequency scanning cycle. Alternatively, the first frequency scanning stage can also be a reverse frequency scanning stage within a frequency scanning cycle, and if the first frequency scanning stage is a reverse frequency scanning stage, the second frequency scanning stage can be a forward frequency scanning stage within a frequency scanning cycle.

[0041] Optionally, the first frequency sweep data can be determined based on the frequency sweep data collected during the first frequency sweep stage, and the second frequency sweep data can be determined based on the frequency sweep data collected during the second frequency sweep stage.

[0042] In some exemplary embodiments, the computer device can acquire first sweep frequency data corresponding to a first sweep frequency stage and second sweep frequency data corresponding to a second sweep frequency stage within a sweep frequency cycle.

[0043] Specifically, the computer equipment can communicate with the OCT equipment to obtain the forward and reverse frequency sweep data of the OCT equipment within one frequency sweep cycle. The forward frequency sweep data is the data collected during the forward frequency sweep phase, and the reverse frequency sweep data is the data collected during the reverse frequency sweep phase.

[0044] Furthermore, the computer equipment can directly determine the forward and reverse frequency sweep data as the first and second frequency sweep data. The computer equipment can also perform data preprocessing on the forward and reverse frequency sweep data to obtain the first and second frequency sweep data.

[0045] Step 102: Perform phase correction processing on the first frequency sweep data to obtain the phase-corrected first frequency sweep data, and determine the third and fourth frequency sweep data based on the second frequency sweep data and the phase-corrected first frequency sweep data.

[0046] Optionally, phase correction processing can eliminate the phase shift caused by the forward and reverse sweep directions during bidirectional frequency sweeping, so that the sweep data in the forward and reverse directions within one sweep cycle are phase matched.

[0047] In some exemplary embodiments, after obtaining the first frequency sweep data and the second frequency sweep data, the computer device can perform phase correction processing on the first frequency sweep data to obtain the phase-corrected first frequency sweep data.

[0048] Specifically, the computer equipment can perform phase correction processing on the first sweep frequency data based on the phase correction algorithm to obtain the phase-corrected first sweep frequency data output by the phase correction model.

[0049] Furthermore, after obtaining the first sweep frequency data after phase correction processing, the computer equipment can determine the third and fourth sweep frequency data based on the second sweep frequency data and the first sweep frequency data after phase correction processing.

[0050] Specifically, the computer equipment can perform post-processing operations on the first and second frequency sweep data after phase correction to obtain the third and fourth frequency sweep data.

[0051] Step 103: Determine the OCT image based on the third and fourth frequency sweep data.

[0052] In some exemplary embodiments, after obtaining the third and fourth frequency scan data, the computer device can determine the OCT image based on the third and fourth frequency scan data.

[0053] Specifically, the computer equipment can integrate the third and fourth frequency scan data, and then determine the OCT image based on the integrated data.

[0054] The aforementioned OCT imaging method first acquires first sweep data corresponding to the first sweep stage and second sweep data corresponding to the second sweep stage within a sweep cycle, with the sweep directions of the first and second sweep stages being opposite. Then, phase correction processing is performed on the first sweep data to obtain phase-corrected first sweep data. Third and fourth sweep data are determined based on the second sweep data and the phase-corrected first sweep data. Finally, an OCT image is determined based on the third and fourth sweep data. The OCT imaging method provided in this application, by performing phase correction processing on the sweep data of one sweep stage within a sweep cycle, achieves phase matching of the sweep data in both directions within a sweep cycle in the frequency domain. Then, an OCT image is determined based on the phase-corrected sweep data. This solves the problem that traditional OCT imaging methods are only applicable to unidirectional sweeps and cannot be compatible with bidirectional sweeps, thus realizing OCT imaging in bidirectional sweep mode.

[0055] In an exemplary embodiment, phase correction processing is performed on the first sweep frequency data to obtain phase-corrected first sweep frequency data, including: shifting the phase of the first sweep frequency data along the wavenumber axis to obtain phase-corrected first sweep frequency data.

[0056] Optionally, the wavenumber axis is a data coordinate axis constructed with light wavelength as the dimension, which can be used to characterize the distribution pattern of swept frequency data as wavelength changes.

[0057] In some exemplary embodiments, after obtaining the first frequency sweep data, the computer device can perform a phase shifting process on the phase of the first frequency sweep data along the wavenumber axis to obtain the first frequency sweep data after phase correction.

[0058] Specifically, the computer equipment can perform phase shifting on the first sweep frequency data based on the wavenumber position to offset the phase shift introduced by the opposite sweep direction, so that the center wavenumber of the first sweep frequency data after phase correction is aligned with that of the second sweep frequency data.

[0059] In an exemplary embodiment, the phase of the first sweep frequency data is shifted along the wavenumber axis to obtain the first sweep frequency data after phase correction, including: determining the shift amount based on the first-order dispersion coefficient and the second-order dispersion coefficient, and shifting the phase of the first sweep frequency data along the wavenumber axis according to the shift amount to obtain the first sweep frequency data after phase correction.

[0060] Optionally, the first-order dispersion coefficients include the first-order dispersion coefficients corresponding to the first and second frequency sweep stages, and the second-order dispersion coefficients include the second-order dispersion coefficients corresponding to the first and second frequency sweep stages. That is, the first-order dispersion coefficients can include the forward first-order dispersion coefficients corresponding to the forward frequency sweep stage and the inverse first-order dispersion coefficients corresponding to the reverse frequency sweep stage, and the second-order dispersion coefficients include the forward second-order dispersion coefficients corresponding to the forward frequency sweep stage and the inverse second-order dispersion coefficients corresponding to the reverse frequency sweep stage.

[0061] In some exemplary embodiments, the computer device may determine the translation amount based on the first-order dispersion coefficient and the second-order dispersion coefficient.

[0062] Specifically, the computer equipment can determine the translation amount based on the first-order dispersion coefficient, the second-order dispersion coefficient, and the influence of eye tissue on the second-order dispersion of the swept laser. For example, the computer equipment can first determine the difference in first-order dispersion coefficients based on the first-order dispersion coefficients corresponding to the first and second sweep stages, then determine the average of the second-order dispersion coefficients based on the second-order dispersion coefficients corresponding to the first and second sweep stages, and finally determine the translation amount based on the difference in first-order dispersion coefficients, the average of the second-order dispersion coefficients, and the influence of eye tissue on the second-order dispersion of the swept laser. This translation amount can be expressed as... , ,in, These are the first-order dispersion coefficients corresponding to the first frequency sweep stage. These are the first-order dispersion coefficients corresponding to the second frequency sweep stage. The mean of the second-order dispersion coefficients. To determine the effect of eye tissue on the second-order dispersion of a frequency-scanning laser, the second-order dispersion parameters of a standard reference sample (such as a model eye) with known dispersion characteristics can be determined during factory calibration, based on the second-order dispersion parameters of the actual eye tissue.

[0063] Furthermore, the computer equipment can also determine the translation amount based on the first-order dispersion coefficient and the second-order dispersion coefficient, that is, the influence of the second-order dispersion of the eye tissue on the swept laser is optional in the process of determining the translation amount.

[0064] In one exemplary embodiment, such as Figure 2 As shown, obtaining the first frequency sweep data corresponding to the first frequency sweep stage and the second frequency sweep data corresponding to the second frequency sweep stage within a frequency sweep cycle includes the following steps:

[0065] Step 201: Obtain the original first frequency sweep data and the original second frequency sweep data collected by the OCT device in one frequency sweep cycle.

[0066] Optionally, the original first frequency sweep data can be the frequency sweep data collected by the OCT device in the first frequency sweep stage, and the original second frequency sweep data can be the frequency sweep data collected by the OCT device in the second frequency sweep stage.

[0067] In some exemplary embodiments, the computer device can acquire the raw first sweep frequency data and the raw second sweep frequency data collected by the OCT device in one sweep frequency cycle.

[0068] Specifically, the computer device can communicate with the OCT device to obtain the original first and second frequency sweep data collected by the OCT device in one frequency sweep cycle.

[0069] Step 202: Resample the original first frequency sweep data and the original second frequency sweep data to obtain the first frequency sweep data and the second frequency sweep data.

[0070] In some exemplary embodiments, after acquiring the original first frequency sweep data and the original second frequency sweep data collected by the OCT device in one frequency sweep cycle, the computer device can perform resampling processing on the original first frequency sweep data and the original second frequency sweep data to obtain the first frequency sweep data and the second frequency sweep data.

[0071] In an optional embodiment of this application, before performing phase correction processing on the first frequency sweep data, the computer device may also perform background spectrum removal processing on the original first frequency sweep data and the original second frequency sweep data.

[0072] The background spectrum includes the first background spectrum corresponding to the original first frequency sweep data and the second background spectrum corresponding to the original second frequency sweep data. The original first frequency sweep data and the original second frequency sweep data are subjected to background spectrum removal processing, that is, the original first frequency sweep data is reduced by the first background spectrum and the original second frequency sweep data is reduced by the second background spectrum.

[0073] The background spectrum can be the spectrum acquired by the OCT device during a no-load scan. It typically includes fixed background signals such as the system's DC component, spontaneous emission noise from the light source, and stray light reflected from the reference arm. By performing background spectrum removal processing on the original first and second frequency scan data after resampling, interference from fixed background signals can be eliminated.

[0074] In one exemplary embodiment, such as Figure 3 As shown, resampling processing is performed on the original first frequency sweep data and the original second frequency sweep data to obtain the first frequency sweep data and the second frequency sweep data, including the following steps:

[0075] Step 301: Obtain the first resampling phase range corresponding to the first frequency sweep stage and the second resampling phase range corresponding to the second frequency sweep stage.

[0076] Optionally, the first resampling phase range may include a continuous phase interval from the start phase point to the end phase point in the first frequency sweep stage, and the second resampling phase range may include a continuous phase interval from the start phase point to the end phase point in the second frequency sweep stage.

[0077] In some exemplary embodiments, the computer device may first obtain the first resampling phase range corresponding to the first frequency sweep stage and the second resampling phase range corresponding to the second frequency sweep stage.

[0078] Step 302: Determine the overlapping resampling phase range based on the first resampling phase range and the second resampling phase range.

[0079] Optionally, the overlapping resampling phase range refers to the common phase range in which the first resampling phase range and the second resampling phase range overlap.

[0080] In some exemplary embodiments, after obtaining the first resampling phase range corresponding to the first frequency sweep stage and the second resampling phase range corresponding to the second frequency sweep stage, the computer device can determine the overlapping resampling phase range based on the first resampling phase range and the second resampling phase range.

[0081] Specifically, the computer device can compare the start and end phases of two phase ranges and select the intersection as the overlapping resampling phase range. For example, if the first resampling phase range is... The second resampling phase range is Then the overlapping resampling phase range is determined to be... .

[0082] Step 303: Resample the original first frequency sweep data and the original second frequency sweep data using the overlapping resampling phase range to obtain the first frequency sweep data and the second frequency sweep data.

[0083] In some exemplary embodiments, after determining the overlapping resampling phase range based on the first resampling phase range and the second resampling phase range, the computer device can use the overlapping resampling phase range to resample the original first sweep frequency data and the original second sweep frequency data to obtain the first sweep frequency data and the second sweep frequency data.

[0084] Specifically, the computer equipment can resample the original first sweep frequency data and the original second sweep frequency data within the overlapping resampling phase range to obtain the first sweep frequency data and the second sweep frequency data.

[0085] The method described above, which obtains the first resampling phase range corresponding to the first frequency sweep stage and the second resampling phase range corresponding to the second frequency sweep stage, determines the overlapping resampling phase range based on the first and second resampling phase ranges, and uses the overlapping resampling phase range to resample the original first and second frequency sweep data to obtain the first and second frequency sweep data, can resample the first and second frequency sweep data to the same wavenumber space, thereby having the same wavenumber sampling interval, which is convenient for subsequent data processing.

[0086] In one exemplary embodiment, such as Figure 4 As shown, the method also includes the following steps:

[0087] Step 401: Obtain the first rising edge and the first falling edge of the first bandpass filter that performs filtering on the clock signal corresponding to the first frequency sweep stage, and obtain the second rising edge and the second falling edge of the second bandpass filter that performs filtering on the clock signal corresponding to the second frequency sweep stage.

[0088] Optionally, the first upper edge is the highest frequency of the passband of the first bandpass filter, and signals above this frequency will be attenuated; the first lower edge is the lowest frequency of the passband of the first bandpass filter, and signals below this frequency will be attenuated. The second upper edge is the highest frequency of the passband of the second bandpass filter, and signals above this frequency will be attenuated; the second lower edge is the lowest frequency of the passband of the second bandpass filter, and signals below this frequency will be attenuated.

[0089] In some exemplary embodiments, the computer device may first obtain the first rising edge and the first falling edge of the first bandpass filter that filters the clock signal corresponding to the first frequency sweep stage, and then obtain the second rising edge and the second falling edge of the second bandpass filter that filters the clock signal corresponding to the second frequency sweep stage.

[0090] Step 402: Determine the target upper edge based on the first upper edge and the second upper edge, and determine the target lower edge based on the first lower edge and the second lower edge.

[0091] In some exemplary embodiments, after the computer device obtains the first rising edge and the first falling edge of the first bandpass filter that filters the clock signal corresponding to the first frequency sweep stage, and obtains the second rising edge and the second falling edge of the second bandpass filter that filters the clock signal corresponding to the second frequency sweep stage, it can determine the target rising edge based on the first rising edge and the second rising edge, and determine the target falling edge based on the first falling edge and the second falling edge.

[0092] Specifically, the computer device can average the first upper edge and the second upper edge to determine the target upper edge, and average the first lower edge and the second lower edge to determine the target lower edge.

[0093] The computer device can also select the larger of the first upper edge and the second upper edge as the target upper edge, and select the smaller of the first lower edge and the second lower edge as the target lower edge.

[0094] Step 403: Resample the original first frequency sweep data and the original second frequency sweep data based on the target upper edge and the target lower edge to obtain the first frequency sweep data and the second frequency sweep data.

[0095] In some exemplary embodiments, after averaging the first upper edge and the second upper edge to determine the target upper edge, and averaging the first lower edge and the second lower edge to determine the target lower edge, the computer device may resample the original first sweep frequency data and the original second sweep frequency data based on the target upper edge and the target lower edge to obtain the first sweep frequency data and the second sweep frequency data.

[0096] The method described above obtains the first rising edge and the first falling edge of the first bandpass filter that filters the clock signal corresponding to the first frequency sweep stage, and the second rising edge and the second falling edge of the second bandpass filter that filters the clock signal corresponding to the second frequency sweep stage. Based on the first rising edge and the second rising edge, a target rising edge is determined, and based on the first falling edge and the second falling edge, a target falling edge is determined. Based on the target rising edge and the target falling edge, the original first frequency sweep data and the original second frequency sweep data are resampled to obtain the first frequency sweep data and the second frequency sweep data. By using the same filter parameters to resample the original first frequency sweep data and the original second frequency sweep data, the dynamic switching of filter parameters can be avoided, reducing system complexity and improving data processing efficiency.

[0097] In one exemplary embodiment, such as Figure 5 As shown, the determination of the third and fourth frequency sweep data based on the second frequency sweep data and the first frequency sweep data after phase correction processing includes the following steps:

[0098] Step 501: Obtain the first dispersion compensation coefficient corresponding to the first frequency sweep stage and the second dispersion compensation coefficient corresponding to the second frequency sweep stage, and average the first dispersion compensation coefficient and the second dispersion compensation coefficient to determine the target dispersion compensation coefficient.

[0099] In an optional embodiment of this application, the first dispersion compensation coefficient includes the second-order dispersion coefficient and the third-order dispersion coefficient corresponding to the first frequency sweep stage; the second dispersion compensation coefficient includes the second-order dispersion coefficient and the third-order dispersion coefficient corresponding to the second frequency sweep stage.

[0100] Optionally, the target dispersion compensation coefficient may include the target second-order dispersion coefficient and the target third-order dispersion coefficient.

[0101] Specifically, the computer equipment can average the second-order dispersion coefficients corresponding to the first frequency sweep stage and the second-order dispersion coefficients corresponding to the second frequency sweep stage to determine the target second-order dispersion coefficient; the computer equipment can also average the third-order dispersion coefficients corresponding to the first frequency sweep stage and the second-order dispersion coefficients corresponding to the second frequency sweep stage to determine the target third-order dispersion coefficient.

[0102] Step 502: Using the target dispersion compensation coefficient, perform dispersion compensation processing on the second sweep frequency data and the first sweep frequency data after phase correction processing to obtain the first sweep frequency data and the second sweep frequency data after dispersion compensation processing.

[0103] In some exemplary embodiments, after obtaining the target dispersion compensation coefficient, the computer device can use the target dispersion compensation coefficient to perform dispersion compensation processing on the second sweep frequency data and the first sweep frequency data after phase correction processing, so as to obtain the first sweep frequency data after dispersion compensation processing and the second sweep frequency data after dispersion compensation processing.

[0104] Specifically, the computer equipment can construct a dispersion compensation phase polynomial based on the target dispersion compensation coefficients. This dispersion compensation phase polynomial can be expressed as follows: Where k is the wave value, The value of the center wave. The target second-order dispersion coefficient, Let be the target third-order dispersion coefficient. Furthermore, in addition to the target second-order and target third-order dispersion coefficients, the dispersion compensation phase polynomial may also include higher-order dispersion compensation terms as well as first-order dispersion compensation terms or constant terms.

[0105] Furthermore, after constructing the dispersion compensation phase polynomial, the computer device can calculate the complex weights corresponding to the wavenumber k point by point along the wavenumber axis. Specifically, for the first sweep data after phase correction processing, the computer device can add the offset wavenumber k to the calculated weights. Substituting the wave value k into the dispersion compensation phase polynomial and taking the exponent yields the first complex weight. For the second sweep frequency data, the computer device can substitute the wave value k into the dispersion compensation phase polynomial and take the exponent to obtain the second complex weight. Then, the first complex weight and the first sweep frequency data after phase correction are multiplied point by point by complex number to obtain the dispersion-compensated first sweep frequency data. The second complex weight and the second sweep frequency data are then multiplied point by point by complex number to obtain the dispersion-compensated second sweep frequency data.

[0106] Step 503: Determine the third and fourth frequency sweep data based on the first and second frequency sweep data after dispersion compensation processing.

[0107] In some exemplary embodiments, after obtaining the first frequency sweep data and the second frequency sweep data after dispersion compensation processing, the computer device can determine the third frequency sweep data and the fourth frequency sweep data based on the first frequency sweep data and the second frequency sweep data after dispersion compensation processing.

[0108] Specifically, the computer equipment can perform post-processing on the first and second frequency sweep data after dispersion compensation to obtain the third and fourth frequency sweep data.

[0109] In an exemplary embodiment, the OCT imaging method further includes: flipping the first sweep frequency data / second sweep frequency data along the wavenumber axis, and performing phase correction processing on the first sweep frequency data after the flipping processing to obtain phase-corrected first sweep frequency data; or, flipping the third sweep frequency data / fourth sweep frequency data along the wavenumber axis, and determining an OCT image based on the third sweep frequency data and the fourth sweep frequency data after the flipping processing.

[0110] In some exemplary embodiments, after obtaining the first and second sweep frequency data, the computer device can flip the first sweep frequency data along the wavenumber axis to obtain the flipped first sweep frequency data. The flipped first and second sweep frequency data have the same wavenumber direction. The computer device then performs phase correction processing on the flipped first sweep frequency data to obtain phase-corrected first sweep frequency data. The computer device can also flip the second sweep frequency data along the wavenumber axis to obtain the flipped second sweep frequency data. The flipped second sweep frequency data and the first sweep frequency data have the same wavenumber direction. After the flipping process, the computer device performs phase correction processing on the first sweep frequency data to obtain phase-corrected first sweep frequency data. Finally, the computer device determines the third and fourth sweep frequency data based on the flipped second sweep frequency data and the phase-corrected first sweep frequency data.

[0111] In other exemplary embodiments, after obtaining the third and fourth sweep frequency data, the computer device can flip the third sweep frequency data along the wavenumber axis to obtain flipped third sweep frequency data. The flipped third and fourth sweep frequency data have the same wavenumber direction, and an OCT image is determined based on the flipped third and fourth sweep frequency data. The computer device can also flip the fourth sweep frequency data along the wavenumber axis to obtain flipped fourth sweep frequency data. The flipped fourth sweep frequency data has the same wavenumber direction as the third sweep frequency data, and an OCT image is determined based on the flipped fourth and third sweep frequency data.

[0112] Furthermore, such as Figure 6 and Figure 7 As shown, Figure 6 The A-scan signal intensity curves corresponding to the first and second frequency sweep data before dispersion compensation processing are shown. Figure 7 The A-scan signal intensity curves corresponding to the first and second frequency sweep data after dispersion compensation processing are shown, where, Figure 6 and Figure 7The positive signal can be the A-scan signal strength corresponding to the first sweep frequency data or the A-scan signal strength corresponding to the second sweep frequency data. When the positive signal is the A-scan signal strength corresponding to the first sweep frequency data, the negative signal is the A-scan signal strength corresponding to the second sweep frequency data; conversely, when the positive signal is the A-scan signal strength corresponding to the second sweep frequency data, the negative signal is the A-scan signal strength corresponding to the first sweep frequency data. Specifically, this is achieved by shifting the wavenumbers of the first sweep frequency data as a whole. This ensures that the first and second swept frequency data have the same center wavenumber in the wavenumber domain. The dispersion compensation phase polynomial, with wavenumber k as the independent variable, performs dispersion compensation on the first swept frequency data after wavenumber shift, ensuring that the dispersion compensation unfolds at the correct wavenumber position. If wavenumber shift is not performed, the dispersion compensation will be applied at the offset wavenumber position, resulting in an inconsistency between the compensated phase-wavenumber relationship and the second swept frequency data. After dispersion compensation, the phase-wavenumber distributions of the two swept frequency data are matched. After Fourier transform to the spatial domain (tissue depth direction), the peak values ​​of the A-scan signals corresponding to the reflections of the same structure are located at the same depth coordinates. Figure 6 It can be seen that before dispersion compensation processing, there is a significant positional deviation between the main peaks of the signals corresponding to the first and second frequency sweep data; Figure 7 As can be seen, after dispersion compensation, the main peaks of the A-scan signals corresponding to the first and second sweep frequency data are precisely aligned, with their peak positions coinciding. This effectively eliminates the axial misalignment of the A-scan caused by the phase deviation introduced by bidirectional sweep frequency. Therefore, by combining phase correction and dispersion compensation, the significant misalignment problem in OCT images under bidirectional sweep frequency mode can be resolved.

[0113] In one exemplary embodiment, such as Figure 8 As shown, determining the OCT image based on the third and fourth frequency scan data includes the following steps:

[0114] Step 801: Determine the initial B-scan image based on the third and fourth frequency scan data.

[0115] In some exemplary embodiments, after obtaining the third and fourth scan data, the computer device can determine an initial B-scan image based on the third and fourth scan data.

[0116] Specifically, the computer equipment can perform a one-dimensional Fourier transform on the third and fourth frequency sweep data, and perform post-processing on the transform results to obtain the initial B-scan image.

[0117] Step 802: Obtain multiple first A-scans and multiple second A-scans from the initial B-scan image.

[0118] Optionally, the first A-scan is obtained based on the third frequency sweep data, and the second A-scan is obtained based on the fourth frequency sweep data.

[0119] In some exemplary embodiments, after determining an initial B-scan image, the computer device may acquire a plurality of first A-scans and a plurality of second A-scans from the initial B-scan image.

[0120] For example, the A-scan corresponding to the odd index in the initial B-scan image can be used as the first A-scan, and the A-scan corresponding to the even index in the initial B-scan image can be used as the second A-scan.

[0121] Step 803: Determine the offset based on multiple first A-scans and multiple second A-scans.

[0122] In some exemplary embodiments, after acquiring a plurality of first A-scans and a plurality of second A-scans in an initial B-scan image, the computer device may determine an offset based on the plurality of first A-scans and the plurality of second A-scans.

[0123] Specifically, the computer device can use feature matching to determine the offset based on multiple first A-scans and multiple second A-scans; the computer device can also use affine transformation to determine the offset based on multiple first A-scans and multiple second A-scans; the computer device can also use template matching to determine the offset based on multiple first A-scans and multiple second A-scans.

[0124] The following section will describe in detail how to determine the offset using template matching based on multiple first A-scans and multiple second A-scans.

[0125] In one alternative approach, the computer device can divide the initial B-scan image into multiple blocks in an ascending A-scan index direction. Each block includes a preset number of first A-scans and a preset number of second A-scans. The computer device can divide all first A-scans within a block into a first sub-block, and all second A-scans into a second sub-block. Taking the matching process of the first and second sub-blocks of one block as an example: using the first sub-block as a reference, the second sub-block is translated by a preset step size, and the cross-correlation coefficient between the two sub-blocks is calculated in real time. The position corresponding to the maximum value of the cross-correlation coefficient is determined as the target position of the second sub-block, and the offset of the sub-block is determined based on the difference between the target position and the initial position of the second sub-block.

[0126] Furthermore, after determining the offset of the sub-block, if the first sub-block is used as a reference, the computer device can perform first-order least squares fitting based on the index of each second A-scan in the second sub-block and the sub-block offset to determine the alignment coefficient, and then determine the offset of each second A-scan through the alignment coefficient and the A-scan index.

[0127] In one alternative approach, the computer device can divide all first A-scans in the initial B-scan image into a first block and all second A-scans into a second block. Using one block as a reference, feature matching is performed on the other block to determine the offset of the corresponding block. Taking the matching process of the first and second blocks as an example: using the first block as a reference, the second block is translated by a preset step size, and the cross-correlation coefficient between the two blocks is calculated in real time. The position corresponding to the maximum value of the cross-correlation coefficient is determined as the target position of the second block. The offset between the second and first blocks is determined based on the difference between the target position and the initial position of the second block.

[0128] Furthermore, the computer device can divide a first block composed of all first A-scans into multiple first sub-blocks, and a second block composed of all second A-scans into multiple second sub-blocks. Each first sub-block includes a preset number of first A-scans, and each second sub-block includes a preset number of second A-scans, with a corresponding relationship between the multiple first sub-blocks and the multiple second sub-blocks. The computer device can use each first sub-block as a reference to perform feature matching on its corresponding second sub-block to determine the offset of each second sub-block.

[0129] Furthermore, after determining the offsets of multiple second sub-blocks, the computer device can average the offsets of the multiple second sub-blocks to obtain the average offset value, and perform first-order least squares fitting based on the center position of each second sub-block and the average offset value to determine the alignment coefficient. Then, the offset of each second A-scan is determined by the alignment coefficient and the A-scan index.

[0130] In an optional embodiment of this application, the computer device can also perform quality evaluation on the first-order least squares fitting result. Specifically, the computer device can calculate the residual or slope of the least squares fitting. If the residual or slope of the least squares fitting meets a preset threshold, the fitting result is determined to be qualified, and the alignment coefficient obtained from the fitting is used to determine the corresponding first A-scan offset. If the residual or slope of the least squares fitting does not meet the preset threshold, the fitting result is determined to be unqualified, and the offset between the second block and the first block is directly used as the offset of each corresponding first A-scan.

[0131] Step 804: Correct the initial B-scan image according to the offset to obtain the OCT image.

[0132] In some exemplary embodiments, after performing feature matching based on multiple first A-scans and multiple second A-scans to determine the offset, the computer device can perform correction processing on the initial B-scan image based on the offset to obtain an OCT image.

[0133] Specifically, given that the obtained offsets correspond to the offsets of each first A-scan, the position of the second A-scan can be kept unchanged. For each first A-scan, its original axial sampling data is linearly interpolated based on the offset corresponding to that A-scan to obtain the corrected first A-scan. Sub-pixel precision axial translation correction is achieved through linear interpolation.

[0134] Furthermore, such as Figure 9 and Figure 10 As shown, Figure 9 The initial B-scan image is shown. Figure 10 The image shown is a B-scan image after correction based on the offset of the initial B-scan image. Figure 9 It can be seen that there is a significant misalignment in the initial B-scan image (some structures in the image appear jagged). The specific details of this jagged misalignment can be seen as follows: Figure 11 As shown; by Figure 10 It can be seen that the B-scan image obtained after correction no longer has obvious misalignment.

[0135] Furthermore, the B-scan image obtained after correction can be used as an OCT image, or the image obtained after further processing the B-scan image obtained after correction can be used as an OCT image.

[0136] The method described above, which determines the initial B-scan image based on the third and fourth frequency sweep data, acquires multiple first A-scans and multiple second A-scans in the initial B-scan image, performs feature matching based on the multiple first A-scans and multiple second A-scans to determine the offset, and performs correction processing on the initial B-scan image according to the offset to obtain the OCT image, effectively eliminates the problem of image misalignment and improves the accuracy of OCT images.

[0137] It should be understood that although the steps in the flowcharts of the embodiments described above are shown sequentially according to the arrows, these steps are not necessarily executed in the order indicated by the arrows. Unless explicitly stated herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders. Moreover, at least some steps in the flowcharts of the embodiments described above may include multiple steps or multiple stages. These steps or stages are not necessarily completed at the same time, but can be executed at different times. The execution order of these steps or stages is not necessarily sequential, but can be performed alternately or in turn with other steps or at least some of the steps or stages in other steps. It is understood that the steps in different embodiments can be freely combined as needed, and all non-contradictory solutions formed by such combinations are within the scope of protection of this application.

[0138] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. An OCT imaging method, characterized in that, The method includes: Acquire the first frequency sweep data corresponding to the first frequency sweep stage and the second frequency sweep data corresponding to the second frequency sweep stage within a frequency sweep cycle, wherein the frequency sweep directions of the first frequency sweep stage and the second frequency sweep stage are opposite. The shift amount is determined based on the first-order dispersion coefficient and the second-order dispersion coefficient. The phase of the first frequency sweep data is shifted along the wavenumber axis according to the shift amount to obtain the first frequency sweep data after phase correction. The first-order dispersion coefficient includes the first-order dispersion coefficient corresponding to the first frequency sweep stage and the first-order dispersion coefficient corresponding to the second frequency sweep stage. The second-order dispersion coefficient includes the second-order dispersion coefficient corresponding to the first frequency sweep stage and the second-order dispersion coefficient corresponding to the second frequency sweep stage. Obtain the first dispersion compensation coefficient corresponding to the first frequency sweep stage and the second dispersion compensation coefficient corresponding to the second frequency sweep stage, and average the first dispersion compensation coefficient and the second dispersion compensation coefficient to determine the target dispersion compensation coefficient; use the target dispersion compensation coefficient to perform dispersion compensation processing on the second frequency sweep data and the first frequency sweep data after phase correction processing to obtain the first frequency sweep data and the second frequency sweep data after dispersion compensation processing; determine the third frequency sweep data and the fourth frequency sweep data based on the first frequency sweep data and the second frequency sweep data after dispersion compensation processing. The OCT image is determined based on the third and fourth frequency sweep data.

2. The method according to claim 1, characterized in that, The step of obtaining the first frequency sweep data corresponding to the first frequency sweep stage and the second frequency sweep data corresponding to the second frequency sweep stage within a frequency sweep cycle includes: Acquire the original first frequency sweep data and the original second frequency sweep data collected by the OCT device in one frequency sweep cycle; the original first frequency sweep data is the frequency sweep data collected by the OCT device in the first frequency sweep stage, and the original second frequency sweep data is the frequency sweep data collected by the OCT device in the second frequency sweep stage; The original first frequency sweep data and the original second frequency sweep data are resampled to obtain the first frequency sweep data and the second frequency sweep data.

3. The method according to claim 2, characterized in that, The step of resampling the original first frequency sweep data and the original second frequency sweep data to obtain the first frequency sweep data and the second frequency sweep data includes: Obtain the first resampling phase range corresponding to the first frequency sweeping stage and the second resampling phase range corresponding to the second frequency sweeping stage; The overlapping resampling phase range is determined based on the first resampling phase range and the second resampling phase range; The original first frequency sweep data and the original second frequency sweep data are resampled using the overlapping resampling phase range to obtain the first frequency sweep data and the second frequency sweep data.

4. The method according to claim 2, characterized in that, The method further includes: Obtain the first rising edge and the first falling edge of the first bandpass filter that performs filtering on the clock signal corresponding to the first frequency sweep stage, and obtain the second rising edge and the second falling edge of the second bandpass filter that performs filtering on the clock signal corresponding to the second frequency sweep stage; The target upper edge is determined based on the first upper edge and the second upper edge, and the target lower edge is determined based on the first lower edge and the second lower edge; The original first frequency sweep data and the original second frequency sweep data are resampled based on the target upper edge and the target lower edge to obtain the first frequency sweep data and the second frequency sweep data.

5. The method according to claim 1, characterized in that, The first dispersion compensation coefficient includes the second-order dispersion coefficient and the third-order dispersion coefficient corresponding to the first frequency sweep stage; the second dispersion compensation coefficient includes the second-order dispersion coefficient and the third-order dispersion coefficient corresponding to the second frequency sweep stage.

6. The method according to claim 1, characterized in that, The method further includes: The first sweep frequency data / the second sweep frequency data are flipped along the wavenumber axis, and after the flipping process, the first sweep frequency data is phase corrected to obtain the first sweep frequency data after phase correction. Alternatively, the third and fourth frequency sweep data can be flipped along the wavenumber axis, and the OCT image can be determined based on the third and fourth frequency sweep data after the flipping process.

7. The method according to any one of claims 1 to 6, characterized in that, Determining the OCT image based on the third and fourth frequency sweep data includes: The initial B-scan image is determined based on the third and fourth frequency scan data; Obtain multiple first A-scans and multiple second A-scans from the initial B-scan image; the first A-scans are obtained based on the third frequency sweep data, and the second A-scans are obtained based on the fourth frequency sweep data; The offset is determined based on the plurality of first A-scans and the plurality of second A-scans; The initial B-scan image is corrected based on the offset to obtain the OCT image.

8. The method according to claim 2, characterized in that, Before resampling the original first frequency sweep data and the original second frequency sweep data, the method further includes: Background spectrum removal processing is performed on the original first frequency sweep data and the original second frequency sweep data.

9. The method according to claim 3, characterized in that, The step of resampling the original first frequency sweep data and the original second frequency sweep data using the overlapping resampling phase range to obtain the first frequency sweep data and the second frequency sweep data includes: Within the overlapping resampling phase range, the original first sweep frequency data and the original second sweep frequency data are resampled to obtain the first sweep frequency data and the second sweep frequency data.

10. The method according to claim 4, characterized in that, The first upper edge is the highest frequency of the passband of the first bandpass filter, and the first lower edge is the lowest frequency of the passband of the first bandpass filter; the second upper edge is the highest frequency of the passband of the second bandpass filter, and the second lower edge is the lowest frequency of the passband of the second bandpass filter.

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