A spectral calibration method for line-field spectral domain OCT system

Abstract

The present application belongs to the field of optical coherence layer imaging, and specifically discloses a spectral calibration method for a line-view spectral domain OCT system, comprising: obtaining the instantaneous phases of interference signals corresponding to two optical path differences by adjusting the lifting platform at the sample mirror in the line-view spectral domain OCT system, and performing subtraction to obtain the instantaneous phase difference; based on a calibration light source, generating discrete spectral lines on the detector by blocking the sample arm in the line-view spectral domain OCT system, and obtaining the spectral intensity distribution corresponding to the calibration light source; calculating the sub-pixel position of the peak of each spectral line and the instantaneous phase difference corresponding to the sub-pixel position based on the instantaneous phase difference and the spectral intensity distribution corresponding to the calibration light source; determining the linear relationship between the instantaneous phase difference and the wavenumber based on the wavenumber and instantaneous phase difference corresponding to each spectral line through linear fitting, and calibrating the corresponding wavenumber based on the linear relationship. Through the present application, a more accurate line-view OCT spectral calibration result can be achieved.

Description

Technical Field

[0001] The present application belongs to the field of optical coherence layer imaging, and more specifically, relates to a spectral calibration method for a line-field spectral domain OCT system. Background Art

[0002] Spectral-Domain Optical Coherence Tomography (SD-OCT) has been widely used in biomedical imaging and industrial inspection due to its non-destructive, high-resolution, and axial scanning-free characteristics. Line-field spectral-domain OCT (LF-SD-OCT) systems leverage the advantages of line-field illumination and high-speed area scan cameras to enable parallel acquisition of multiple A-scans, significantly improving imaging speed. However, their image quality depends largely on the accuracy of spectral calibration. Traditional line-field spectral-domain OCT systems typically calibrate the backend imaging spectrometer separately, using known spectral line data from the calibration light source to directly fit a polynomial to the wavelength-pixel relationship. However, this approach is often limited by the order of the fitting polynomial: To obtain an accurate pixel-to-wavelength (or wavenumber) mapping, a polynomial of appropriate order must be selected. Too low an order makes it difficult to describe spectral nonlinearities; too high an order can lead to overfitting and amplify noise. The selection of the polynomial order relies on empirical experience and lacks physical significance or objective criteria. Furthermore, in linear field-of-view spectral domain OCT systems, the imaging spectrometer typically performs secondary imaging on the relay image transmitted by the interferometer arm. Aberrations in the front-end interferometer arm and installation errors can cause discrepancies between the actual spectral distribution and the calibrated spectral data. Achieving higher-precision linear field-of-view OCT spectral calibration is a pressing technical challenge in this field. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the purpose of this application is to effectively improve the calibration accuracy of line-field OCT spectra.

[0004] To achieve the above objectives, in a first aspect, the present application provides a spectral calibration method for a line-field spectral domain OCT system, comprising:

[0005] The first optical path difference is obtained by adjusting the lifting platform at the sample mirror in the line field spectral domain OCT system The corresponding instantaneous phase of the interference signal The instantaneous phase of the interference signal corresponding to the second optical path difference And subtract the instantaneous phase of the interference signal corresponding to the two optical path differences to obtain the instantaneous phase difference , the first optical path difference and the second optical path difference are different, Represents the pixel index of the detector in the line-field spectral domain OCT system;

[0006] Based on the calibration light source, by blocking the sample arm in the line field spectral domain OCT system, discrete spectral lines are generated on the detector, and the spectral intensity distribution corresponding to the calibration light source is obtained. ;

[0007] Based on the instantaneous phase difference Spectral intensity distribution corresponding to the calibration light source , calculate the sub-pixel position of the peak of each spectral line and sub-pixel positions The corresponding instantaneous phase difference , Indicates the number of the spectral line;

[0008] Based on the wave number corresponding to each spectral line and instantaneous phase difference , through linear fitting, determine the linear relationship between instantaneous phase difference and wave number, and calibrate based on the linear relationship Corresponding wave number .

[0009] In a possible implementation, the first optical path difference is obtained by adjusting the lifting platform at the sample mirror in the line field spectral domain OCT system. The corresponding instantaneous phase of the interference signal The instantaneous phase of the interference signal corresponding to the second optical path difference ,include:

[0010] The optical path difference is and The AC quantity of the interference signal is obtained at the position and ;

[0011] AC quantity based on interference signal and , the complex interference signal is obtained by Hilbert transform and , unwrap the phase term of the complex interference signal to obtain and .

[0012] In one possible implementation, the sub-pixel position of the peak of each spectral line is calculated ,include:

[0013] Based on the spectral intensity distribution corresponding to the calibration light source , determine the sub-pixel position of the peak of each spectral line by the energy center of gravity method ECCM .

[0014] In one possible implementation, the sub-pixel position is calculated The corresponding instantaneous phase difference ,include:

[0015] Based on the sub-pixel position of the peak of each spectral line , through Interpolate to determine sub-pixel position The corresponding instantaneous phase difference .

[0016] In one possible implementation, the spectral intensity distribution corresponding to the calibration light source is obtained. ,include:

[0017] Based on the discrete spectral lines generated on the detector, the spectral intensity distribution corresponding to the calibration light source is determined by enhancing the spectral line signal. .

[0018] In one possible implementation, based on linear relationship calibration Corresponding wave number After that, it also includes:

[0019] By the first optical path difference The corresponding instantaneous phase of the interference signal Perform a first-order fit to determine the nonlinear term introduced by the dispersion mismatch between the two arms; or, The corresponding instantaneous phase of the interference signal Perform a first-order fit to determine the nonlinear term introduced by the dispersion mismatch between the two arms;

[0020] Based on the nonlinear term, dispersion compensation is performed on the line-field spectral domain OCT system.

[0021] In a possible implementation, the method further includes:

[0022] Calibrate different field of view channels along the target direction Corresponding wave number , the target direction is perpendicular to the direction of spectrum expansion on the detector image plane.

[0023] In a second aspect, the present application provides a spectral calibration device for a line-field spectral domain OCT system, comprising:

[0024] The instantaneous phase difference acquisition module is used to obtain the first optical path difference by adjusting the lifting platform at the sample mirror in the line field spectral domain OCT system. The corresponding instantaneous phase of the interference signal The instantaneous phase of the interference signal corresponding to the second optical path difference And subtract the instantaneous phase of the interference signal corresponding to the two optical path differences to obtain the instantaneous phase difference , the first optical path difference and the second optical path difference are different, Represents the pixel index of the detector in the line-field spectral domain OCT system;

[0025] The discrete spectral line generation module is used to generate discrete spectral lines on the detector based on the calibration light source by blocking the sample arm in the line field spectral domain OCT system, and obtain the spectral intensity distribution corresponding to the calibration light source. ;

[0026] Spectral line peak sub-pixel position calculation module, used for instantaneous phase difference Spectral intensity distribution corresponding to the calibration light source , calculate the sub-pixel position of the peak of each spectral line and sub-pixel positions The corresponding instantaneous phase difference , Indicates the number of the spectral line;

[0027] Calibration module, used to calculate the wave number corresponding to each spectral line and instantaneous phase difference , through linear fitting, determine the linear relationship between instantaneous phase difference and wave number, and calibrate based on the linear relationship Corresponding wave number .

[0028] In a third aspect, the present application provides an electronic device comprising: at least one memory for storing programs; and at least one processor for executing the programs stored in the memory. When the program stored in the memory is executed, the processor is used to execute the method described in the first aspect or any possible implementation of the first aspect.

[0029] In a fourth aspect, the present application provides a computer-readable storage medium, which stores a computer program. When the computer program runs on a processor, the processor executes the method described in the first aspect or any possible implementation of the first aspect.

[0030] In general, the above technical solutions conceived by this application have the following beneficial effects compared with the existing technologies:

[0031] (1) By obtaining the instantaneous phase difference , calculate the sub-pixel position of the peak of each spectral line and sub-pixel positions The corresponding instantaneous phase difference , can determine the linear relationship between instantaneous phase difference and wave number through linear fitting, and then calibrate based on the linear relationship Corresponding wave number This method can make full use of the phase information contained in the interference fringes and establish a more rigorous calibration model. It can eliminate the interference of the dispersion term caused by the dispersion mismatch between the two arms (reference arm and sample arm) during the calibration process, and take into account the offset between the spectral channels of different sampling points. The above calibration operation can be performed on each field of view, which can achieve higher-precision line-field OCT spectral calibration results.

[0032] (2) Considering that the energy of the calibration light source coupled into the system from the optical fiber is relatively weak, the calibration accuracy can be improved by enhancing the calibration light source signal.

[0033] (3) Analyze and evaluate the system’s dispersion, and then make software and hardware compensation to reduce the interference caused by dispersion mismatch. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 1 is a flow chart of a spectral calibration method for a line-field spectral domain OCT system provided in an embodiment of the present application;

[0035] Figure 2 Schematic diagram of the structure of the spectral calibration of the line-field spectral domain OCT system provided in the embodiment of the present application;

[0036] Figure 3 This is a schematic diagram of adjusting the optical path difference of the sample arm provided in an embodiment of the present application;

[0037] Figure 4 Schematic diagram of interference fringes on the image plane at different optical path difference positions provided by an embodiment of the present application;

[0038] Figure 5 This is a light path diagram for generating fitting data points provided in an embodiment of the present application;

[0039] Figure 6 It is a two-dimensional spectrum diagram formed on the image plane by the calibration light source provided in the embodiment of the present application;

[0040] Figure 7 Schematic diagram of the structure of a spectral calibration device for a line-field spectral domain OCT system provided in an embodiment of the present application;

[0041] Figure 8 It is a structural diagram of an electronic device provided in an embodiment of the present application.

[0042] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0043] 1 is a computer; 2 is a light source; 3 is a fiber collimator; 4 is a cylindrical lens; 5 is a beam splitter; 6 is a relay lens; 7 is an imaging spectrometer; 8 is an achromatic lens; 9 is a reference mirror; 10 is an objective lens; 11 is a sample mirror; 12 is a Z-axis lifting platform; 13 is a light baffle; 14 is an instantaneous phase difference acquisition module; 15 is a discrete spectral line generation module; 16 is a spectral line peak sub-pixel position calculation module; 17 is a calibration module. DETAILED DESCRIPTION

[0044] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0045] The terms "first," "second," and the like in the specification and claims herein are used to distinguish between different objects, rather than to describe a specific order of objects. For example, "first optical path difference" and "second optical path difference" are used to distinguish between different optical path differences, rather than to describe a specific order of optical path differences.

[0046] In the embodiments of this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of this application should not be interpreted as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0047] In the description of the embodiments of the present application, unless otherwise specified, "multiple" means two or more, for example, multiple processing units means two or more processing units, etc.; multiple elements means two or more elements, etc.

[0048] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0049] Figure 1 FIG. 1 is a flow chart of a spectral calibration method for a line-view spectral domain OCT system provided in an embodiment of the present application. Figure 1 As shown, the method includes the following steps S101 to S104.

[0050] Step S101, by adjusting the lifting platform at the sample mirror in the line field spectral domain OCT system, a first optical path difference is obtained. The corresponding instantaneous phase of the interference signal The instantaneous phase of the interference signal corresponding to the second optical path difference And subtract the instantaneous phase of the interference signal corresponding to the two optical path differences to obtain the instantaneous phase difference , the first optical path difference and the second optical path difference are different, Represents the pixel index of the detector in the line-field spectral domain OCT system;

[0051] Step S102: Based on the calibration light source, by blocking the sample arm in the line field spectral domain OCT system, discrete spectral lines are generated on the detector, and the spectral intensity distribution corresponding to the calibration light source is obtained. ;

[0052] Step S103, based on the instantaneous phase difference Spectral intensity distribution corresponding to the calibration light source , calculate the sub-pixel position of the peak of each spectral line and sub-pixel positions The corresponding instantaneous phase difference , Indicates the number of the spectral line;

[0053] Step S104: based on the wave number corresponding to each spectral line and instantaneous phase difference , through linear fitting, determine the linear relationship between instantaneous phase difference and wave number, and calibrate based on the linear relationship Corresponding wave number .

[0054] The working principle of the calibration method provided in this application is explained below.

[0055] Usually, the interferometer arm of the line-field spectral domain interferometric imaging system consists of a reference arm and a sample arm, and a cylindrical lens is introduced to form a line illumination on the sample surface. The imaging spectrometer can perform spectral imaging on the relay image of the sample at the line illumination point, and then obtain the A-scan signal of each field of view by performing fast Fourier transform on the spectra of different field of view channels. Assuming that on the image plane of the two-dimensional array detector (hereinafter referred to as the detector) in the imaging spectrometer, the horizontal direction is the direction of spectral expansion, and the vertical direction corresponds to different field of view channels, then in this type of imaging system, it is necessary to find the following pixel index p and wave number for each row channel on the detector surface through spectral calibration The mapping relationship The calibration method proposed in this application is based on the phase change of interference fringes and is explained using the spectral signal of the central visual field as an example.

[0056] Figure 2This system is designed to calibrate a linear field-of-view spectral domain interferometry imaging system. The system includes a computer 1 for control and data processing and a linear field-of-view spectral domain interferometry imaging system (linear field-of-view spectral domain OCT system). The linear field-of-view spectral domain interferometry imaging system consists of a light source 2, a fiber collimator 3, a cylindrical lens 4, a beam splitter 5, a reference arm, a sample arm, a relay lens 6, and a custom imaging spectrometer 7. The reference arm includes an achromatic doublet lens 8 and a reference mirror 9; the sample arm includes an objective lens 10, a sample mirror 11, and a z-axis lift 12. The two arms are symmetrical, with the reference mirror fixed in position. In specific system designs, the two arms can be asymmetrical, and the light spot on the reference mirror can be a point. This can be achieved by adding a cylindrical lens to the reference arm. Figure 2 The light source in may specifically be a broadband light source.

[0057] The interferometric AC signal generated in the wavenumber domain when the position of the reference mirror is fixed and there is only one reflector on the sample arm It can be written as:

[0058] (1)

[0059] in, is the spectral distribution function of the light source, and are the reflection coefficients of the reference mirror and the sample mirror respectively. The first three terms are combined and simplified to , is the optical path difference between the two arms, It is a nonlinear term introduced by the dispersion mismatch between the two arms. The complex interference signal can be constructed through Hilbert transform and the instantaneous phase can be obtained. :

[0060] (2)

[0061] in, The actual phase difference , n is an integer. Due to the dispersion term existence, In order to eliminate the dispersion term during the phase linearization calibration process, the instantaneous phases of the interference signals at two different optical path differences are subtracted:

[0062] (3)

[0063] From this we can see that and There is a linear relationship, so:

[0064] (4).

[0065] It is understandable that the instantaneous phase difference is obtained by the present application. , calculate the sub-pixel position of the peak of each spectral line and sub-pixel positions The corresponding instantaneous phase difference , can determine the linear relationship between instantaneous phase difference and wave number through linear fitting, and then calibrate based on the linear relationship Corresponding wave number This method can make full use of the phase information contained in the interference fringes and establish a more rigorous calibration model. It can eliminate the interference of the dispersion term caused by the dispersion mismatch between the two arms (reference arm and sample arm) during the calibration process, and take into account the offset between the spectral channels of different sampling points, which can achieve more accurate line-field OCT spectral calibration results.

[0066] In addition, it is worth noting that the spectral calibration of traditional line-field spectral domain OCT systems only assumes that ideal point objects in different fields of view are located on the front focal plane of the imaging spectrometer, and thus the light source is directly placed in front of the slit of the imaging spectrometer for calibration. However, during actual measurement, the slit position is not an ideal point object, but a primary image produced by the sample to be measured, which has aberrations, which will cause the system calibration results to deviate significantly from the actual situation. The spectral calibration process of the present application makes the focal line spots of different wavelengths on the image plane and the position of the optical fiber output end conjugate in the horizontal direction. It passes through the reference arm to the image plane, taking into account the entire propagation process, and is more consistent with the actual measurement process. At the same time, the general SD-OCT system changes the optical path difference between the two arms by adjusting the position of the reference mirror, while the system calibrated in the present application fixes the position of the reference mirror, and places the mechanical structure used to adjust the optical path difference between the two arms on the sample arm, so that the spectrum generated by the reference mirror in the imaging spectrometer remains unchanged. This setting makes the spectral calibration results stable, and light of the same wavelength will always interfere at a fixed position on the image plane without offset.

[0067] The following describes several examples of the spectral calibration method for a line-field spectral domain OCT system provided in this application. The method includes: (1) calculating a curve showing the phase difference as a function of spatial position; (2) generating discrete spectral lines; (3) enhancing the spectral line signals; (4) calculating the sub-pixel position and corresponding phase difference of the peak of each spectral line; (5) completing spectral calibration by estimating parameters a and b using least squares fitting; and (6) estimating dispersion.

[0068] (1) Calculate the curve of phase difference changing with spatial position: First, Figure 3 As shown, adjust the z-axis lifting platform so that the optical path difference is and The AC quantity of the interference signal is collected and calculated at the position and , the interference fringes on the image plane at different optical path differences are as follows Figure 4As shown, the complex signal (complex interference signal) is obtained by Hilbert transform, and the phase terms of each complex signal are unwrapped to obtain and , use the difference between the two to calculate . Figure 4 middle Indicates the image field of view.

[0069] (2) Generate discrete spectral lines: block the sample arm and couple the light emitted by the calibration light source into the spatial light path (refer to Figure 5 , Figure 5 The light source in the image is specifically the calibration light source), and finally the fixed reference arm generates a two-dimensional discrete spectrum with precise position on the detector surface, such as Figure 6 The calibration light source must be highly stable and produce discrete, known wavelengths. This can be a laser or a spectral lamp (xenon, neon, or mercury). To provide more fitting data, spectral line signals generated by different light sources can be combined.

[0070] (3) Enhanced spectral line signal: To solve the problem of weak spectral signals of some calibration light sources, it is necessary to enhance the signal. For example, the integration time can be extended and multi-frame averaging noise reduction methods can be used to collect images containing spectral line signals and separate background noise. The enhanced spectral signal is obtained by subtracting the latter from the former. .

[0071] (4) Calculate the sub-pixel position and corresponding phase difference of the peak of each spectral line: Based on the discrete spectral signal, Sub-pixel position of the peak of each spectral line To make an estimate, for example, the Energy Center of Gravity Method (ECCM) can be used:

[0072] (5)

[0073] Here, the value of n is set to 2. is the spectral intensity distribution corresponding to the calibration light source, For the The pixel index corresponding to the peak of the spectrum line. Interpolation, we get Position corresponding to .

[0074] Here, the sub-pixel position of the spectral line peak is explained. Spectral line data is usually collected in discrete pixels. The integer pixel index corresponding to the peak of the discrete spectral line signal cannot represent the actual position of the spectral line peak. The actual peak position may be located between these pixels. Therefore, the sub-pixel position of the spectral line peak needs to be estimated.

[0075] (5) The least squares fitting estimates the parameters a and b to complete the spectrum calibration: Based on the prior information of the calibration light source, we know that , Indicates the The wavelength corresponding to the spectral line, thus obtaining the data point , perform straight line fitting to estimate the parameters and .Will Substitute into formula (4) to complete the calibration.

[0076] (6) Dispersion estimation;

[0077] In order to evaluate the dispersion of the system, the calibration results can be used to or Perform a first-order fit and calculate the residual, which is the nonlinear term. Based on this nonlinear term, targeted dispersion compensation can be made to the system through software or hardware.

[0078] In addition, considering that the single-wavelength line spot is not an ideal vertical straight line on the image plane, there will be a certain degree of curvature, which will cause the spectra of different fields of view to shift. Therefore, the above calibration operation needs to be performed for each field of view.

[0079] The spectral calibration device for the line-field-of-view spectral domain OCT system provided in this application is described below. The spectral calibration device for the line-field-of-view spectral domain OCT system described below and the spectral calibration method for the line-field-of-view spectral domain OCT system described above can be referenced to each other.

[0080] Figure 7 Schematic diagram of the structure of the spectral calibration device for the line field spectral domain OCT system provided in the embodiment of the present application, such as Figure 7 As shown, the device includes: an instantaneous phase difference acquisition module 14, a discrete spectrum line generation module 15, a spectrum line peak sub-pixel position calculation module 16 and a calibration module 17.

[0081] The instantaneous phase difference acquisition module 14 is used to obtain the first optical path difference by adjusting the lifting platform at the sample mirror in the line field spectral domain OCT system. The corresponding instantaneous phase of the interference signal The instantaneous phase of the interference signal corresponding to the second optical path difference And subtract the instantaneous phase of the interference signal corresponding to the two optical path differences to obtain the instantaneous phase difference , the first optical path difference and the second optical path difference are different, Represents the pixel index of the detector in the line-field spectral domain OCT system;

[0082] The discrete spectral line generation module 15 is used to generate discrete spectral lines on the detector based on the calibration light source by blocking the sample arm in the line field spectral domain OCT system, and obtain the spectral intensity distribution corresponding to the calibration light source. ;

[0083] Spectral line peak sub-pixel position calculation module 16, for calculating the peak sub-pixel position based on the instantaneous phase difference Spectral intensity distribution corresponding to the calibration light source , calculate the sub-pixel position of the peak of each spectral line and sub-pixel positions The corresponding instantaneous phase difference , Indicates the number of the spectral line;

[0084] Calibration module 17, used for wave number corresponding to each spectral line and instantaneous phase difference , through linear fitting, determine the linear relationship between instantaneous phase difference and wave number, and calibrate based on the linear relationship Corresponding wave number .

[0085] It is understandable that the detailed functional implementation of each of the above units / modules can be found in the introduction of the aforementioned method embodiment, and will not be repeated here.

[0086] It should be understood that the above-mentioned device is used to execute the method in the above-mentioned embodiment. The implementation principle and technical effect of the corresponding program module in the device are similar to those described in the above-mentioned method. The working process of the device can refer to the corresponding process in the above-mentioned method and will not be repeated here.

[0087] Based on the method in the above embodiment, an embodiment of the present application provides an electronic device, Figure 8 is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application, such as Figure 8 As shown, the electronic device may include: a processor (Processor) 810, a communication interface (Communications Interface) 820, a memory (Memory) 830 and a communication bus 840, wherein the processor 810, the communication interface 820, and the memory 830 communicate with each other via the communication bus 840. The processor 810 can call the logic instructions in the memory 830 to execute the method in the above embodiment.

[0088] In addition, the logic instructions in the aforementioned memory 830 can be implemented in the form of a software functional unit and, when sold or used as an independent product, can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application, or the portion that contributes to the prior art, or the portion of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a number of instructions for enabling a computer device (which can be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in each embodiment of the present application.

[0089] Based on the method in the above embodiment, an embodiment of the present application provides a computer-readable storage medium, which stores a computer program. When the computer program runs on a processor, the processor executes the method in the above embodiment.

[0090] Based on the method in the above embodiment, an embodiment of the present application provides a computer program product. When the computer program product runs on a processor, the processor executes the method in the above embodiment.

[0091] It is understood that the processor in the embodiments of the present application may be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA), other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor.

[0092] The method steps in the embodiments of the present application can be implemented by hardware or by a processor executing software instructions. The software instructions can be composed of corresponding software modules, which can be stored in random access memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, mobile hard disks, CD-ROMs, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor so that the processor can read information from the storage medium and write information to the storage medium. Of course, the storage medium can also be an integral part of the processor. The processor and storage medium can be located in an ASIC.

[0093] The above embodiments can be implemented in whole or in part using software, hardware, firmware, or any combination thereof. When implemented using software, they can be implemented in whole or in part in the form of a computer program product. The computer program product comprises one or more computer instructions. When loaded and executed on a computer, the computer program instructions fully or partially produce the processes or functions described in the embodiments of this application. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted via the computer-readable storage medium. The computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium accessible by a computer or a data storage device such as a server or data center that integrates one or more available media. The available medium can be magnetic media (e.g., floppy disk, hard disk, tape), optical media (e.g., DVD), or semiconductor media (e.g., solid-state drive (SSD)).

[0094] It will be understood that the various numerical numbers involved in the embodiments of the present application are merely distinctions for the convenience of description and are not intended to limit the scope of the embodiments of the present application.

[0095] It is easy for those skilled in the art to understand that the above is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A spectral calibration method for a line-field spectral domain OCT system, characterized in that: include: The first optical path difference is obtained by adjusting the lifting platform at the sample mirror in the line field spectral domain OCT system The corresponding instantaneous phase of the interference signal The instantaneous phase of the interference signal corresponding to the second optical path difference And subtract the instantaneous phase of the interference signal corresponding to the two optical path differences to obtain the instantaneous phase difference , the first optical path difference and the second optical path difference are different, Represents the pixel index of the detector in the line-field spectral domain OCT system; Based on the calibration light source, by blocking the sample arm in the line field spectral domain OCT system, discrete spectral lines are generated on the detector, and the spectral intensity distribution corresponding to the calibration light source is obtained. ; Based on the instantaneous phase difference Spectral intensity distribution corresponding to the calibration light source , calculate the sub-pixel position of the peak of each spectral line and sub-pixel positions The corresponding instantaneous phase difference , Indicates the number of the spectral line; Based on the wave number corresponding to each spectral line and instantaneous phase difference , through linear fitting, determine the linear relationship between instantaneous phase difference and wave number, and calibrate based on the linear relationship Corresponding wave number .

2. The spectral calibration method for a line-field spectral domain OCT system according to claim 1, characterized in that: The first optical path difference is obtained by adjusting the lifting platform at the sample mirror in the line field spectral domain OCT system. The corresponding instantaneous phase of the interference signal The instantaneous phase of the interference signal corresponding to the second optical path difference ,include: The optical path difference is and The AC quantity of the interference signal is obtained at the position and ; AC quantity based on interference signal and , the complex interference signal is obtained by Hilbert transform and , unwrap the phase term of the complex interference signal to obtain and .

3. The spectral calibration method for a line-field spectral domain OCT system according to claim 1, characterized in that: The sub-pixel position of the peak of each spectral line is calculated ,include: Based on the spectral intensity distribution corresponding to the calibration light source , determine the sub-pixel position of the peak of each spectral line by the energy center of gravity method ECCM .

4. The spectral calibration method for a line-field spectral domain OCT system according to claim 1, characterized in that: Calculating sub-pixel positions The corresponding instantaneous phase difference ,include: Based on the sub-pixel position of the peak of each spectral line , through Interpolate to determine sub-pixel position The corresponding instantaneous phase difference .

5. The spectral calibration method for a line-field spectral domain OCT system according to claim 1, characterized in that: The spectral intensity distribution corresponding to the calibration light source is obtained ,include: Based on the discrete spectral lines generated on the detector, the spectral intensity distribution corresponding to the calibration light source is determined by enhancing the spectral line signal. .

6. The spectral calibration method for a line-field spectral domain OCT system according to claim 1, characterized in that: Based on linear relationship calibration Corresponding wave number After that, it also includes: By the first optical path difference The corresponding instantaneous phase of the interference signal Perform a first-order fit to determine the nonlinear term introduced by the dispersion mismatch between the two arms; or, The corresponding instantaneous phase of the interference signal Perform a first-order fit to determine the nonlinear term introduced by the dispersion mismatch between the two arms; Based on the nonlinear term, dispersion compensation is performed on the line-field spectral domain OCT system.

7. The spectral calibration method for a line-field spectral domain OCT system according to claim 1, characterized in that: Also includes: Calibrate different field of view channels along the target direction Corresponding wave number , the target direction is perpendicular to the direction of spectrum expansion on the detector image plane.

8. A spectral calibration device for a line-field spectral domain OCT system, characterized in that: include: The instantaneous phase difference acquisition module is used to obtain the first optical path difference by adjusting the lifting platform at the sample mirror in the line field spectral domain OCT system. The corresponding instantaneous phase of the interference signal The instantaneous phase of the interference signal corresponding to the second optical path difference And subtract the instantaneous phase of the interference signal corresponding to the two optical path differences to obtain the instantaneous phase difference , the first optical path difference and the second optical path difference are different, Represents the pixel index of the detector in the line-field spectral domain OCT system; The discrete spectral line generation module is used to generate discrete spectral lines on the detector based on the calibration light source by blocking the sample arm in the line field spectral domain OCT system, and obtain the spectral intensity distribution corresponding to the calibration light source. ; Spectral line peak sub-pixel position calculation module, used for instantaneous phase difference Spectral intensity distribution corresponding to the calibration light source , calculate the sub-pixel position of the peak of each spectral line and sub-pixel positions The corresponding instantaneous phase difference , Indicates the number of the spectral line; Calibration module, used to calculate the wave number corresponding to each spectral line and instantaneous phase difference , through linear fitting, determine the linear relationship between instantaneous phase difference and wave number, and calibrate based on the linear relationship Corresponding wave number .

9. An electronic device, characterized in that: include: at least one memory for storing a computer program; At least one processor is used to execute the program stored in the memory. When the program stored in the memory is executed, the processor is used to execute the method according to any one of claims 1 to 7.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed on a processor, the processor is caused to execute the method according to any one of claims 1 to 7.

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