Phase correction method, device and equipment for optical imaging, medium and product

Abstract

The invention provides a phase correction method and device for optical imaging, equipment, a medium and a product, and the method comprises the steps: obtaining non-linear correction data which is a phase correction array obtained by carrying out the non-winding phase extraction and the non-linear phase correction of a glass surface interferogram collected by an optical imaging system in advance; and controlling the optical imaging system to perform interferogram acquisition on the target object to obtain an interferogram of the target object, performing phase correction on the interferogram of the target object based on the nonlinear correction data in an image reconstruction process, and performing reconstruction based on the corrected interferogram to obtain a reconstructed image of the target object. According to the embodiment of the invention, non-linear distortion in an optical imaging system can be effectively eliminated, the influence of a non-linear effect on an imaging effect is reduced, on the basis of ensuring the imaging effect, the complexity of data processing is reduced, faster image reconstruction can be realized, the method is suitable for real-time imaging requirements, and the efficiency of image reconstruction is improved.

Description

Technical Field

[0001] The present invention relates to the field of optical imaging technology, and in particular to a phase correction method, device, equipment, medium and product for optical imaging. Background Art

[0002] In the process of optical imaging, due to the influence of light characteristics and system equipment, the collected light signal will inevitably have nonlinear effects, which will affect the axial resolution of the image and reduce the imaging quality.

[0003] The inventors have found that in related imaging technologies, an interpolation method is usually used to correct the interference signal collected by the optical system, and resampling is performed through post-processing based on the correction information to achieve nonlinear correction to improve imaging quality. However, the calculation process of this type of interpolation processing method is complicated, making it difficult to achieve real-time image reconstruction, which reduces the efficiency of image reconstruction. Summary of the invention

[0004] The present invention provides a phase correction method, device, equipment, medium and product for optical imaging to solve the problem.

[0005] In a first aspect, an embodiment of the present application provides a phase correction method for optical imaging, comprising:

[0006] Acquire nonlinear correction data, the nonlinear correction data being a phase correction array obtained by performing non-entanglement phase extraction on a glass surface interference pattern collected by an optical imaging system in advance, and nonlinear phase correction;

[0007] Controlling the optical imaging system to collect interference patterns of the target object to obtain the interference patterns of the target object;

[0008] During the image reconstruction process, the interference pattern of the target object is phase corrected based on the nonlinear correction data, and a reconstructed image of the target object is obtained based on the corrected interference pattern.

[0009] Optionally, performing phase correction on the interference pattern of the target object based on the nonlinear correction data, and reconstructing a reconstructed image of the target object based on the corrected interference pattern includes:

[0010] The window function used in the image reconstruction process is optimized based on the nonlinear correction data to obtain an improved correction filter function;

[0011] The interference signal correction processing is performed on the interference pattern of the target object according to the correction filter function, and the image is reconstructed according to the corrected interference pattern to obtain a reconstructed image of the target object.

[0012] Optionally, performing interference signal correction processing on the interference pattern of the target object according to the correction filter function, and performing image reconstruction according to the corrected interference pattern to obtain a reconstructed image of the target object, including:

[0013] Perform DC signal removal processing on the interference pattern of the target object to obtain an effective interference signal;

[0014] Performing Fourier transform on the effective interference signal, and performing inverse Fourier transform on the frequency domain signal after Fourier transform to obtain a filtered time domain signal;

[0015] The correction filter function is used to perform nonlinear correction and dispersion compensation on the filtered time domain signal to obtain a correction interference signal;

[0016] An image of the target object is reconstructed based on the corrected interference signal to obtain a reconstructed image of the target object.

[0017] Optionally, the nonlinear correction data is determined by:

[0018] Controlling the optical imaging system to collect interference patterns on the glass surface to obtain interference patterns on the glass surface;

[0019] Perform effective signal extraction on the collected glass surface interference pattern to obtain an effective time domain signal of the glass surface interference pattern;

[0020] Performing Hilbert transform on the effective time domain signal to obtain the target analytical signal, and performing non-entanglement phase extraction on the target analytical signal to obtain the non-entanglement phase of the glass surface interference pattern;

[0021] The linear phase difference between the non-winding phase and the ideal straight line of the interference pattern on the glass surface is determined to obtain nonlinear correction data, and the ideal straight line is a straight line determined according to the non-winding phase.

[0022] Optionally, performing Hilbert transform on the effective time domain signal to obtain a target analytical signal, and performing non-entanglement phase extraction on the target analytical signal to obtain a non-entanglement phase of the glass surface interference pattern, including:

[0023] Performing Hilbert transform on the effective time domain signal to obtain the target analytical signal after expanding the effective time domain signal;

[0024] Perform phase analysis on the target analysis signal to extract the instantaneous phase of the interference pattern on the glass surface;

[0025] The instantaneous phase of the interference pattern on the glass surface is processed by non-wrapping phase, and the non-wrapping phase with continuous phase distribution in the interference pattern on the glass surface is obtained.

[0026] Optionally, the ideal straight line is a straight line passing through the first and last points of the non-wrapped phase, and the linear phase difference between the non-wrapped phase of the glass surface interference pattern and the ideal straight line is determined to obtain nonlinear correction data, including:

[0027] Determine the linear phase of the ideal straight line according to the first phase point and the last phase point of the non-winding phase;

[0028] The nonlinear correction data is determined based on the phase difference between the non-wrapped phase of the interference pattern on the glass surface and the linear phase of the ideal straight line.

[0029] Optionally, performing effective signal extraction on the collected glass surface interference pattern to extract an effective time domain signal of the glass surface interference pattern includes:

[0030] The DC signal is removed from the collected interference pattern of the glass surface, and the interference signal after the DC signal is removed is subjected to Fourier transformation and signal isolation to obtain the target frequency domain signal;

[0031] The target frequency domain signal is inversely Fourier transformed to obtain the effective time domain signal of the glass surface interference pattern.

[0032] In a second aspect, an embodiment of the present application provides an image processing device, including:

[0033] An acquisition module is used to acquire nonlinear correction data, wherein the nonlinear correction data is a phase correction array obtained by performing non-entanglement phase extraction on a glass surface interference pattern collected by an optical imaging system in advance, and nonlinear phase correction;

[0034] A control module, used to control the optical imaging system to collect interference patterns of the target object to obtain the interference patterns of the target object;

[0035] The reconstruction module is used to perform phase correction on the interference pattern of the target object based on the nonlinear correction data during the image reconstruction process, and reconstruct the reconstructed image of the target object based on the corrected interference pattern.

[0036] In a third aspect, an embodiment of the present application provides an electronic device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor implements the steps of the above-mentioned phase correction method for optical imaging when executing the computer program.

[0037] In a fourth aspect, an embodiment of the present application provides a readable storage medium, which stores a computer program. When the computer program is executed by a processor, the steps of the above-mentioned phase correction method for optical imaging are implemented.

[0038] In a fifth aspect, an embodiment of the present application provides a computer program product, the computer program product includes a computer program, and when the computer program is executed by a processor, the steps of the phase correction method for optical imaging are implemented.

[0039] In one solution provided by the above-mentioned phase correction method, device, equipment, medium and product for optical imaging, nonlinear correction data is obtained, and the nonlinear correction data is a phase correction array obtained by performing non-entangled phase extraction on the glass surface interference pattern collected by the optical imaging system in advance, and nonlinear phase correction; the optical imaging system is controlled to collect the interference pattern of the target object to obtain the interference pattern of the target object, and in the image reconstruction process, the interference pattern of the target object is phase corrected based on the nonlinear correction data, and the reconstructed image of the target object is obtained based on the corrected interference pattern reconstruction. In this embodiment, by effectively performing phase correction on the interference pattern by pre-stored nonlinear correction data, the nonlinear distortion in the optical imaging system can be effectively eliminated, and the influence of the nonlinear effect on the imaging effect is reduced. On the basis of ensuring the imaging effect, it is simpler than the interpolation method in the related technology, reduces the complexity of data processing, can achieve faster image reconstruction, is suitable for real-time imaging needs, and improves the efficiency of image reconstruction. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0041] Figure 1 is a schematic structural diagram of an optical imaging system in one embodiment of the present invention;

[0042] Figure 2 is a flow chart of a phase correction method for optical imaging in one embodiment of the present invention;

[0043] Figure 3 is another structural schematic diagram of an optical imaging system in one embodiment of the present invention;

[0044] Figure 4 is a schematic diagram of a process for obtaining nonlinear correction data in one embodiment of the present invention;

[0045] Figure 5 yes Figure 2 A schematic diagram of an implementation process of step S30;

[0046] Figure 6is a schematic diagram of a nonlinear correction data acquisition process and an interference pattern correction process in one embodiment of the present invention;

[0047] Figure 7 is a schematic diagram of an image reconstruction process in one embodiment of the present invention;

[0048] Figure 8 yes Figure 1 A structural schematic diagram of an image processing device;

[0049] Fig. 9 It is a schematic diagram of the structure of an electronic device in one embodiment of the present invention. DETAILED DESCRIPTION

[0050] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or their collections. It should also be understood that the term "and / or" used in the present specification and the appended claims refers to any combination of one or more of the associated listed items and all possible combinations, and includes these combinations.

[0052] In addition, in the description of the present specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0053] References to "one embodiment" or "some embodiments" etc. described in the present specification mean that one or more embodiments of the present invention include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0054] It should be understood that the order of execution of the steps in the following embodiments does not imply a precedence of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0055] In order to illustrate the technical solution of the present invention, specific embodiments are provided below for illustration.

[0056] Swept Source Optical Coherence Tomography (SSOCT) is a high-resolution biomedical imaging technology that has important applications in the biomedical field, especially in large-volume imaging of biological samples. SSOCT provides microscopic and depth-resolved images through interference imaging, which can reveal fine structures such as blood vessels and axon fiber bundles. In order to achieve high-quality imaging of biological samples, the microscopic resolution and axial resolution of the reconstructed image are crucial.

[0057] The axial resolution of SSOCT is closely related to the spectral characteristics of the light source. During the imaging process, since the optical imaging system may be affected by equipment characteristics, environmental factors (such as temperature, humidity) or optical design during actual operation, the interference pattern collected by the system has nonlinear phase deviation, that is, nonlinear effect. In addition, due to the influence of the optical system layout and the preservation conditions of biological samples, the signals collected by the system have dispersion effects, such as dispersion caused by the asymmetry of the optical path and dispersion caused by the immersion of biological samples in water. These factors will cause signal distortion, making it impossible for the system to reconstruct a true sample image. In order to reduce the impact of nonlinear effects and dispersion effects on imaging effects, it is necessary to correct the signal nonlinearity and compensate for the signal dispersion during the optical imaging process to improve the axial resolution of the image and improve the imaging quality. In related imaging technologies, signal nonlinearity correction or dispersion compensation is usually performed by introducing hardware equipment or signal numerical processing.

[0058] For example, to solve the problem of signal nonlinearity, a Mach-Zehnder interferometer is used to generate a linear clock to achieve signal linearization, but the introduction of hardware equipment will increase the complexity and cost of the system; or a linear wavenumber swept light source is used, but this light source is expensive and only corrects the nonlinearity of the light source wavenumber, but fails to correct the nonlinearity at the optical path level, and the correction effect is not good. A common numerical processing method is to use an interpolation method to correct the interference signal collected by the optical system, and to perform resampling through post-processing based on the correction information to achieve nonlinear correction. However, the calculation process of this type of interpolation processing method is complicated, and it is difficult to achieve real-time image reconstruction, which reduces the efficiency of image reconstruction. In addition, to solve the dispersion problem, dispersion compensation is usually achieved by replicating the optical path of the sample arm, but it will increase the complexity of the system; and the commonly used numerical processing dispersion compensation methods, such as iterative optimization of phase or differential phase measurement using mirror signals, have a relatively complicated processing process, making it difficult to achieve real-time image reconstruction, and the efficiency of image reconstruction is low.

[0059] In order to solve the above technical problems, the phase correction method for optical imaging provided by the embodiment of the present invention can be applied in the following aspects: Figure 1 In the optical imaging system shown, the optical imaging system includes an optical system and an image processing device, wherein each client communicates with a server via a network.

[0060] In actual application, that is, during the operation of the optical imaging system, the image processing device acquires nonlinear correction data, wherein the nonlinear correction data is a phase correction array obtained by performing non-entanglement phase extraction on the glass surface interference pattern collected by the optical imaging system in advance, and nonlinear phase correction; then the image processing device controls the optical system of the optical imaging system to collect the interference pattern of the target object, and obtains the interference pattern of the target object; in the image reconstruction process, the interference pattern of the target object is phase corrected based on the nonlinear correction data, and a reconstructed image of the target object is obtained based on the corrected interference pattern.

[0061] In this embodiment, the interferogram is effectively phase corrected by pre-stored nonlinear correction data, which can effectively eliminate the nonlinear distortion in the optical imaging system and reduce the impact of the nonlinear effect on the imaging effect. On the basis of ensuring the imaging effect, it is simpler than the interpolation method in the related art, reduces the complexity of data processing, can achieve faster image reconstruction, is suitable for real-time imaging needs, and improves the efficiency of image reconstruction. In addition, the interferogram can be effectively phase corrected by pre-stored nonlinear correction data, and the dispersion problem caused by the asymmetric optical layout and the water medium can be compensated, thereby improving the accuracy and resolution of the image and improving the imaging quality.

[0062] In this scheme, the nonlinear correction data not only includes the wavenumber nonlinear correction factor, but also combines the dispersion information of the optical system, which can compensate for the dispersion effect introduced by the storage conditions of the object or the asymmetry of the optical path; in the image reconstruction process, the interference pattern is effectively corrected by the pre-stored nonlinear correction data, and the image reconstruction can be achieved by linearizing the non-entangled phase in the interference pattern, so that the nonlinear correction and dispersion compensation can be completed simultaneously in the image reconstruction process, realizing the seamless integration of dispersion compensation and wavenumber nonlinear correction. This process can effectively reduce the signal acquisition error caused by the nonlinear effect and dispersion effect of the system, and effectively simplify the data processing process while ensuring the image quality, improve the efficiency of image reconstruction, and do not require additional hardware support, reducing the system cost.

[0063] The optical imaging system may be a swept source optical coherence tomography system, i.e., an SSOCT system. The image processing device may be a control and image processing device of the SSOCT system. The image processing device may be various terminal devices, such as various personal computers, laptops, smart phones, tablet computers, servers and other devices; the server may be implemented as an independent server or a server cluster composed of multiple servers. In other embodiments, the image processing device may also be various electronic control units.

[0064] In one embodiment, if Figure 2 As shown, a phase correction method for optical imaging is provided, and the method is applied in Figure 1 The image processing device in the optical imaging system is taken as an example to illustrate, comprising the following steps:

[0065] S10: Acquire nonlinear correction data.

[0066] During the operation of the optical imaging system, the image processing device obtains nonlinear correction data, wherein the nonlinear correction data is a phase correction array obtained by performing non-entanglement phase extraction on the glass surface interference pattern collected by the optical imaging system in advance and nonlinear phase correction, that is, a phase correction array.

[0067] S20: Control the optical imaging system to collect interference patterns of the target object to obtain the interference patterns of the target object.

[0068] The image processing device controls the optical system in the optical imaging system, collects interference patterns of the target object, and obtains the interference patterns of the target object.

[0069] The optical imaging system may be a swept source optical coherence tomography system, such as Figure 3As shown, the optical imaging system includes an optical system, a displacement stage and an image processing device (i.e., the digitizer in the figure). The optical system may include a balanced detector, a light source, an optical coupler (OC), a beam splitter (BS), a silver reflector of a reference arm, an objective lens of a sample arm, and a galvanometer in the X direction (i.e., the horizontal direction). Among them, the light source may be a 1030nm swept frequency light source for generating a light beam. The balanced detector is used to form an interference signal and collect an interference pattern. The galvanometer is a galvanometer in the X direction. The displacement stage is used to place target objects, such as glass samples or biological samples, such as biological tissue slices; the displacement stage may be a Y-direction displacement stage capable of displacement in the Y direction (perpendicular to the X direction). The light source in this embodiment is an infrared light source to reduce the impact of the environment on the light.

[0070] Among them, the control of the optical imaging system to collect the interference pattern of the target object and obtain the interference pattern of the target object includes: after detecting that the target object is placed on the translation stage below the objective lens, the image processing device controls the frequency sweeping light source to emit a light beam, and the light beam passes through the fiber optical circulator OC and the beam splitter BS, and then the light beam of the sample arm is expanded to 8mm in diameter through the galvanometer, fills the aperture behind the objective lens and is accurately focused on the surface of the target object on the translation stage, and then the light beam is reflected from the surface of the target object and through the objective lens and the galvanometer back to the beam splitter BS. At the same time, the light beam of the reference arm is compensated by the optical fiber with the same path length as the sample arm, and then reflected back to the beam splitter BS by the silver mirror. The reflected light beam returned by the sample arm and the reflected light beam returned by the reference arm are returned to the balanced detector through the fiber optical circulator OC, and interference is generated at the balanced detector. Finally, the interference signal formed by the two reflected light beams is collected by the 200MHz balanced detector to obtain the interference pattern of the target object, and sent to the image processing device (i.e., the digitizer in the figure) for recording and storage.

[0071] The interference pattern of the target object is collected by a balanced detector of the optical imaging system. It is the result of interference between the light signals of the sample arm and the reference arm, and usually contains wavenumber nonlinearity and dispersion effects.

[0072] S30: During the image reconstruction process, phase correction is performed on the interference pattern of the target object based on the nonlinear correction data, and a reconstructed image of the target object is obtained based on the corrected interference pattern.

[0073] After obtaining the interference map of the target object, the image processing device performs image reconstruction based on the interference map. During the image reconstruction process, the image processing device performs phase correction on the interference map of the target object based on the nonlinear correction data, and reconstructs the reconstructed image of the target object based on the corrected interference map.

[0074] In this embodiment, the interferogram is effectively phase corrected by pre-stored nonlinear correction data, which can effectively eliminate the nonlinear distortion in the optical imaging system and reduce the impact of the nonlinear effect on the imaging effect. On the basis of ensuring the imaging effect, it is simpler than the interpolation method in the related art, reduces the complexity of data processing, can achieve faster image reconstruction, is suitable for real-time imaging needs, and improves the efficiency of image reconstruction. In addition, the interferogram can be effectively phase corrected by pre-stored nonlinear correction data, and the dispersion problem caused by the asymmetric optical layout and the water medium can be compensated, thereby improving the accuracy and resolution of the image and improving the imaging quality.

[0075] In this scheme, the interferogram is effectively phase corrected by pre-stored nonlinear correction data, and image reconstruction can be achieved by linearizing the non-entangled phase in the interferogram, so that both nonlinear correction and dispersion compensation can be realized in the image reconstruction process, reducing the errors caused by system nonlinearity and dispersion. While ensuring image quality, it effectively simplifies the data processing process and improves the efficiency of image reconstruction.

[0076] In one embodiment, the glass surface interference pattern collected by the optical imaging system can be first obtained, and the nonlinear correction data obtained by performing non-wrapping phase extraction and nonlinear phase correction on the glass surface interference pattern can be used to correct the interference pattern of the target object in the subsequent operation of the optical imaging system, so as to reconstruct the reconstructed image of the target object. Figure 4 As shown, the process of obtaining nonlinear correction data specifically includes the following steps:

[0077] S01: Control the optical imaging system to collect interference patterns on the glass surface to obtain interference patterns on the glass surface.

[0078] Specifically, after detecting that a smooth glass sample is placed on the translation stage below the objective lens, the image processing device controls the frequency sweeping light source to emit a light beam, and the light beam passes through the fiber optic circulator OC and the beam splitter BS, and then the light beam of the sample arm is divided into two beams: the sample arm and the reference arm. After the light beam of the sample arm is expanded to a diameter of 8 mm by the galvanometer, it fills the aperture behind the objective lens and is precisely focused on the surface of the target object on the translation stage. Then the light beam is reflected back to the beam splitter BS from the surface of the target object through the objective lens and the galvanometer. At the same time, the light beam of the reference arm is compensated by the optical fiber with the same path length as the sample arm, and then reflected back to the beam splitter BS by the silver mirror. The reflected light beam returned by the sample arm and the reflected light beam returned by the reference arm are returned to the balanced detector through the fiber optic circulator OC, and interference is generated at the balanced detector. Finally, the interference signal formed by the two reflected light beams is collected by a 200MHz balanced detector to obtain the interference pattern of the glass sample, that is, the interference pattern of the glass surface is obtained, and sent to the image processing device (i.e., the digitizer in the figure) for recording and storage.

[0079] S02: extracting effective signals from the collected glass surface interference pattern to obtain effective time domain signals of the glass surface interference pattern.

[0080] The effective signal extraction is performed on the collected glass surface interference pattern, and the steps of the effective signal extraction at least include direct current signal removal, Fourier transform and inverse Fourier transform, so as to extract the effective time domain signal of the glass surface interference pattern.

[0081] It should be understood that the interference pattern collected by the system is the result of interference between the sample arm and the reference arm light signal, and the interference pattern usually contains wave number nonlinearity and dispersion effects. At the same time, the interference pattern collected by the system includes two parts: a DC signal and an interference signal. The DC signal in the interference pattern refers to a signal in the interference signal that does not change according to the phase difference between the reference arm and the sample arm. In the optical imaging system of this embodiment, the DC signal usually refers to the average light intensity component in the output of the balanced detector that does not change with interference. It mainly consists of the following two parts: the average light intensity of the reference arm and the sample arm, and the bias and noise of the balanced detector or electronic circuit. When the broadband light emitted by the light source enters the reference arm and the sample arm respectively, it is reflected back to the boronized detector by their respective reflectors or by the target object. These echo lights produce a background light intensity on the detector that does not change with the depth interference modulation, that is, the average light intensity of the reference arm and the sample arm. The bias voltage or dark current of the balanced detector itself and the back-end collection electronic circuit will also form a DC bias component that is not related to interference in the dry signal, that is, the bias and noise of the balanced detector or electronic circuit.

[0082] Therefore, in order to extract an effective interference signal, the image processing device can remove the DC signal from the collected glass surface interference pattern to obtain a clean interference signal after isolating the DC signal, that is, to obtain an effective interference signal after removing the DC signal. By removing the DC component (i.e., the background light intensity part) in the interference pattern, low-frequency noise can be eliminated and the effective part of the interference signal can be extracted to improve the accuracy of subsequent signal processing and extraction.

[0083] There are many ways to remove the DC signal. For example, during the signal acquisition process, a rough object can be used to block the sample arm of the optical system to make the interference signal disappear, and the DC signal can be acquired and saved by a balanced detector to obtain a standard DC signal; after acquiring the interference pattern on the glass surface, the image processing device subtracts the standard DC signal from the signal in the interference pattern on the glass surface to obtain an effective interference signal after removing the DC signal, which is simple and convenient.

[0084] After removing the DC signal from the collected glass surface interference pattern, the image processing device performs Fourier transform on the effective interference signal after removing the DC signal, and can filter out the interference signal of noise or low-frequency components in the frequency domain to obtain the frequency domain signal after Fourier transform, and then perform inverse Fourier transform on the frequency domain signal after Fourier transform to return the frequency domain signal to the time domain, extract the effective time domain signal of the glass surface interference pattern, and improve the accuracy of the effective time domain signal.

[0085] S03: Performing Hilbert transform on the effective time domain signal to obtain a target analytical signal, and performing non-entanglement phase extraction on the target analytical signal to obtain a non-entanglement phase of the glass surface interference pattern.

[0086] After extracting the effective time domain signal of the glass surface interference pattern, the image processing device can perform Hilbert transform on the effective time domain signal, and perform signal expansion on the real effective time domain signal through Hilbert transform to obtain a target analytical signal including a real signal and an imaginary signal. The real signal of the target analytical signal is the effective time domain signal of the glass surface interference pattern; the imaginary signal of the target analytical signal is the phase deflection signal after the effective time domain signal is Hilbert transformed.

[0087] Then, the image processing device extracts the unwrapped phase of the target analytical signal, that is, unwrapping the wrapped phase of the target analytical signal to obtain the unwrapped signal phase, that is, the unwrapped phase of the glass surface interference pattern. This process can accurately obtain the phase information in the interference pattern, effectively reduce the errors caused by the phase wrapping problem, ensure accurate phase data, and provide a more reliable basis for subsequent data calculations.

[0088] S04: Determine the linear phase difference between the non-entangled phase of the interference pattern on the glass surface and the ideal straight line to obtain nonlinear correction data.

[0089] It should be understood that the ideal straight line means that under ideal conditions (no wave number nonlinearity and no noise), the phase distribution of the interference signal should change linearly, that is, the phase of the ideal straight line changes linearly with the change of wave number; in order to quantify the nonlinear phase difference of the interference signal, it is necessary to compare the non-winding phase with the linear phase of the ideal straight line.

[0090] Therefore, the image processing device can first determine the linear phase of the ideal straight line, which can be represented by a linear function with the wave number of the interference signal as a variable; then the image processing device can determine the linear phase difference between the non-wrapped phase of the interference pattern on the glass surface and the ideal straight line to obtain nonlinear correction data. The nonlinear correction data can effectively characterize the nonlinear errors caused by the optical system, equipment characteristics, environmental factors and pigment effects. The subsequent use of the nonlinear correction data for nonlinear error correction can effectively eliminate the nonlinear error of the optical imaging system acquisition signal, improve the accuracy of the final image, and reduce the image distortion caused by the nonlinear characteristics of the system.

[0091] The ideal straight line is a straight line determined according to the non-winding phase of the glass surface interference pattern. For example, the ideal straight line can be a straight line passing through the first phase point (i.e., the first phase point) and the last phase point (i.e., the last phase point) of the non-winding phase. In other embodiments, the ideal straight line can also be other straight lines determined according to the non-winding phase of the glass surface interference pattern; for example, multiple standard phase points are selected in the non-winding phase of the glass surface interference pattern, and the multiple standard phase points at least include the first phase point, the last phase point, and the middle phase point of the non-winding phase, and then a straight line passing through the multiple standard phase points is determined as the ideal straight line.

[0092] In this embodiment, the optical imaging system is controlled to collect interference patterns on the glass surface to obtain the glass surface interference pattern, and effective signal extraction is performed on the collected glass surface interference pattern to extract the effective time domain signal of the glass surface interference pattern; the effective time domain signal is Hilbert transformed to obtain the target analytical signal, and the target analytical signal is subjected to non-winding phase extraction to obtain the non-winding phase of the glass surface interference pattern; the linear phase difference between the non-winding phase of the glass surface interference pattern and the ideal straight line is determined to obtain nonlinear correction data, and the ideal straight line is a straight line passing through the first and last points of the non-winding phase. This scheme can effectively extract the nonlinear error of the optical imaging system acquisition signal and obtain nonlinear correction data by performing DC removal, Fourier transform, Hilbert transform and non-winding phase extraction on the glass surface interference pattern, and then determining the linear phase difference between the non-winding phase of the glass surface interference pattern and the ideal straight line, so as to improve the imaging quality and accuracy.

[0093] In one embodiment, step S02, namely, extracting effective signals from the collected glass surface interference pattern to obtain effective time domain signals of the glass surface interference pattern, specifically includes the following steps:

[0094] S021: removing the DC signal from the collected glass surface interference pattern, and performing Fourier transform and signal isolation on the interference signal after the DC signal is removed to obtain a target frequency domain signal.

[0095] The image processing device can remove the DC signal from the collected glass surface interference pattern to obtain an effective interference signal after removing the DC signal, effectively eliminating the low-frequency interference in the glass surface interference pattern caused by noise, light source unevenness, environmental factors, etc., so that the remaining signal can more truly reflect the glass surface characteristics, which helps to improve the accuracy of subsequent processing.

[0096] The image processing device performs Fourier transform on the effective interference signal after removing the DC signal, and can filter out the interference signal of noise or low-frequency components in the frequency domain to obtain the frequency domain signal after Fourier transform; then the frequency domain signal after Fourier transform is isolated to remove clutter, that is, the clutter around the peak of the frequency domain signal after Fourier transform is smoothed, and a clean target frequency domain signal is extracted, which can improve the accuracy of the target frequency domain signal and the accuracy of subsequent phase extraction. This process can convert the signal from the time domain to the frequency domain and extract the effective frequency domain signal, so that the target frequency domain signal contains the high-frequency information of the glass surface to accurately reflect the characteristics of the microstructure of the glass surface, and provide more accurate and detailed frequency components for extracting effective frequency domain signal processing.

[0097] S022: Perform inverse Fourier transform on the target frequency domain signal to obtain an effective time domain signal of the glass surface interference pattern.

[0098] The image processing device performs an inverse Fourier transform on the target frequency domain signal to return the frequency domain signal to the time domain, extracts the effective time domain signal of the glass surface interference pattern, and improves the accuracy of the effective time domain signal and the accuracy of subsequent phase extraction.

[0099] In this embodiment, by removing the DC signal, performing Fourier transform and signal isolation, the effective time domain signal of the glass surface interference pattern is successfully extracted, which can significantly improve the signal quality, reduce noise and errors, and optimize the accuracy of the extracted signal; at the same time, through Fourier transform and inverse transform, the interference signal on the glass surface can be efficiently processed, the details of the glass surface can be quickly restored, the ability of the effective time domain signal to restore the details of the glass surface is improved, and the accuracy of the effective time domain signal is improved.

[0100] In one embodiment, step S03, i.e., performing Hilbert transform on the effective time domain signal to obtain the target analytical signal, and performing non-entanglement phase extraction on the target analytical signal to obtain the non-entanglement phase of the glass surface interference pattern, specifically includes the following steps:

[0101] S031: Perform Hilbert transform on the effective time domain signal to obtain a target analytical signal after the effective time domain signal is expanded.

[0102] After extracting the effective time domain signal of the glass surface interference pattern, the image processing device can perform Hilbert transform on the effective time domain signal to obtain a phase deflection signal of the effective time domain signal. Hilbert transform can be achieved by convolution, setting all negative frequency components in the effective time domain signal to zero, retaining the positive frequency components, and obtaining a phase deflection signal of the effective time domain signal. The process of Hilbert transform is represented by the following formula:

[0103]

[0104] Among them, S(t) is the effective time domain signal of the glass surface interference pattern, which consists of a set of signals that change with time t; H[S(t)] is the phase deflection signal of the effective time domain signal; represents the normalization constant, which comes from the characteristics of Fourier transform, and ensures that the amplitude of the transformed signal is consistent with the original signal; τ represents the integral transform, which represents an integral virtual time variable, which is obtained by convolution operation of S(t); S(τ) represents the signal at time τ in signal S(t).

[0105] After obtaining the phase deflection signal of the effective time domain signal, the image processing device generates a target analytical signal including a real signal and an imaginary signal according to the phase deflection signal and the effective time domain signal obtained by the Hilbert transform. The real signal of the target analytical signal is the effective time domain signal of the glass surface interference pattern; the imaginary signal of the target analytical signal is the phase deflection signal after the Hilbert transform of the effective time domain signal.

[0106] Among them, the target analysis signal can be expressed by the following formula:

[0107]

[0108] in, represents the target analytical signal; S(t) represents the effective time domain signal of the glass surface interference pattern; H[S(t) represents the phase deflection signal of the effective time domain signal; j represents the coefficient of the imaginary signal, which is the imaginary unit, usually a constant value, and can be a constant value; H[·] represents the Hilbert transform.

[0109] S032: Perform phase analysis on the target analysis signal to extract the instantaneous phase of the interference pattern on the glass surface.

[0110] After obtaining the target analysis signal, the image processing device performs phase analysis on the target analysis signal to extract the instantaneous phase of the interference pattern on the glass surface.

[0111] Specifically, the image processing device can perform signal conversion on the target analysis signal to obtain the target analysis signal expressed by amplitude and phase, and then analyze the amplitude and phase of the target analysis signal to extract the instantaneous phase of the interference pattern on the glass surface.

[0112] Among them, the instantaneous phase of the interference pattern on the glass surface can be advanced by the following formula:

[0113]

[0114]

[0115] in, represents the target analytical signal; φ(t) represents the instantaneous phase of the glass surface interference pattern; A(t) represents the amplitude of the target analytical signal. In general, the amplitude of the target analytical signal is the effective time domain signal S(t) of the glass surface interference pattern, that is, A(t) = S(t), and A(t) represents the real signal of the target analytical signal; e jφ(t) represents the phase information of the target analytical signal, which includes the instantaneous phase φ(t) of the target analytical signal. jφ(t) Represents the imaginary signal of the target analytical signal. Represents the imaginary signal of the target analytical signal, that is, e jφ(t) ; represents the real signal of the target analytical signal, i.e. A(t). j represents the coefficient of the imaginary signal.

[0116] The instantaneous phase reflects the phase information of the signal at a specific moment, which is crucial for understanding the temporal changes and spatial structure of the signal, especially in interference images, which can reveal tiny deformations or detailed changes on the surface of an object.

[0117] S033: performing non-wrapping phase processing on the instantaneous phase of the interference pattern on the glass surface to obtain a non-wrapping phase with continuous phase distribution in the interference pattern on the glass surface.

[0118] After extracting the instantaneous phase of the glass surface interference pattern, the image processing device performs non-wrapping phase processing on the instantaneous phase of the glass surface interference pattern to obtain a non-wrapping phase with a continuous phase distribution in the glass surface interference pattern. By performing non-wrapping phase processing on the instantaneous phase of the glass surface interference pattern, the influence of phase jumps can be eliminated, making the obtained phase distribution smoother and continuous, ensuring that the phase distribution of the signal is not interfered by camouflage phenomena (such as phase discontinuity or distortion caused by noise, nonlinear effects, etc.), thereby improving the accuracy and reliability of the measurement.

[0119] The extracted instantaneous phase φ(t) is usually a wrapping phase in the range of [-π,π]. The wrapping phase means that due to the periodic restrictions of the phase definition, its value is limited to the range of [-π,π]. When the actual phase change of the signal exceeds this range, discontinuous phase jumps will occur. In order to solve the phase jump situation, the instantaneous phase needs to be unwrapped, that is, non-wrapped phase processing. This process requires detecting the jump point of the instantaneous phase and compensating the jump point with a phase difference of 2π to obtain the non-wrapped phase of the glass surface interference pattern, ensuring the continuous distribution of the signal phase and more accurately reflecting the actual phase change. Among them, the non-wrapped phase of the glass surface interference pattern can be obtained by the following method:

[0120] φ unwrap (t) = φ(t) + 2π·n;

[0121] Among them, φ unwrap (t) represents the non-wrapping phase of the interference pattern on the glass surface; φ(t) represents the instantaneous phase of the interference pattern on the glass surface; n is an integer. When the phase change of the signal determined by n crosses π, it is determined that there is a phase jump, and the phase difference of 2π is automatically compensated for the jump point to ensure phase continuity and obtain the non-wrapping phase of the interference pattern on the glass surface.

[0122] In this embodiment, the effective time domain signal is subjected to Hilbert transform to obtain the target analytical signal after the effective time domain signal is expanded; the target analytical signal is subjected to phase analysis to extract the instantaneous phase of the glass surface interference pattern; the instantaneous phase of the glass surface interference pattern is subjected to non-wrapping phase processing to obtain the non-wrapping phase with continuous phase distribution in the glass surface interference pattern. By analyzing the phase and non-wrapping phase processing, the discontinuity or abnormal phase points caused by noise, optical distortion or errors in signal processing can be effectively reduced, making the signal processing result more stable and accurate, and can better reflect the real characteristics of the target object such as the glass surface.

[0123] In one embodiment, the ideal straight line is a straight line passing through the first phase point and the last phase point of the non-wrapped phase. In step S04, the linear phase difference between the non-wrapped phase of the glass surface interference pattern and the ideal straight line is determined to obtain nonlinear correction data, which specifically includes the following steps:

[0124] S041: Determine the linear phase of the ideal straight line according to the first phase point and the last phase point of the non-wrapped phase of the interference pattern on the glass surface.

[0125] In this embodiment, the ideal straight line is a straight line passing through the first phase point (i.e., the first phase point) and the last phase point (i.e., the last phase point) of the non-winding phase, which is used to represent the ideal state of wave number linearization. The image processing device determines the linear phase of the ideal straight line based on the first phase point and the last phase point of the non-winding phase of the glass surface interference pattern. Among them, the slope and intercept of the ideal straight line are first determined according to the positions of the first phase point and the last phase point of the non-winding phase of the glass surface interference pattern, and the linear relationship between the phase of the ideal straight line and the wave number is determined according to the slope and intercept of the ideal straight line, so as to obtain the linear phase of the ideal straight line. Among them, the linear phase of the ideal straight line can be expressed by the following formula:

[0126] φ ideal (k) = m·k + b;

[0127] Among them, φ ideal (k) represents the linear phase of the ideal straight line, which represents the relationship between the phase of the ideal straight line and the wave number k; k represents the wave number, that is, the phase change rate of the wave, which is the inverse of the wavelength λ; m represents the slope of the ideal straight line; b represents the intercept of the ideal straight line, and m and b are determined by the first phase point and the last phase point of the non-winding phase of the interference pattern on the glass surface.

[0128] Among them, the slope m of the ideal straight line and the intercept b of the ideal straight line are determined by the following formula:

[0129]

[0130] b=φ unwrap (k 1 )-m·k 1 ;

[0131] Among them, m represents the slope of the ideal straight line; b represents the intercept of the ideal straight line; φ unwrap (k 1 ) represents the phase of the first phase point in the non-entangled phase of the interference pattern on the glass surface; φ unwrap (k 2 ) represents the phase of the tail phase point in the non-wrapped phase of the interference pattern on the glass surface; k 1 k represents the wave number at the first phase point in the unwrapped phase of the interference pattern on the glass surface; 2 Represents the wave number at the tail phase point in the unwrap phase of the interference pattern on the glass surface.

[0132] S042: Determine nonlinear correction data according to the phase difference between the non-entangled phase of the glass surface interference pattern and the linear phase of the ideal straight line.

[0133] It is important to understand that in order to quantify the nonlinear phase difference between the glass surface interference pattern and the actual signal of the target object, that is, the nonlinear phase difference caused by the optical imaging system acquisition, it is necessary to compare the non-winding phase of the glass surface interference pattern with the linear phase of the ideal straight line. Since the linear phase of the ideal straight line is a set of data that varies with the wave number, the non-winding phase of the glass surface interference pattern is converted from the phase data that varies with time to the non-winding phase that varies with the wave number, and the converted non-winding phase that varies with the wave number is obtained. Then, the phase difference between the non-winding phase of the converted glass surface interference pattern and the linear phase of the ideal straight line is determined, that is, the nonlinear phase difference between the two that varies with the wave number is determined, and the nonlinear correction data is determined based on the phase difference between the two.

[0134] Among them, the phase difference between the non-entangled phase of the interference pattern on the glass surface and the linear phase of the ideal straight line can be expressed by the following formula:

[0135] δk=φ unwrap (k)-φ ideal (k);

[0136] Among them, δk represents the nonlinear phase difference that varies with wave number, that is, the phase difference between the non-entangled phase of the interference pattern on the glass surface and the linear phase of the ideal straight line; φ unwrap (k) represents the unwrap phase of the interference pattern on the glass surface, i.e., the unwrap phase that varies with the wave number; φ ideal (k) represents the linear phase of the ideal straight line.

[0137] After determining the phase difference between the non-entangled phase of the interference pattern on the glass surface and the linear phase of the ideal straight line, a complex phase correction array, i.e., a complex phase correction array, is constructed according to the phase difference to obtain nonlinear correction data in order to compensate for wave number nonlinearity. The nonlinear correction data can be expressed by the following formula:

[0138] C(t)=e -jδk(k) ;

[0139] Wherein, C(t) represents the nonlinear correction data, that is, the nonlinear correction factor that varies with time; δk represents the nonlinear phase difference that varies with wave number k, that is, the phase difference between the non-entangled phase of the interference pattern on the glass surface and the linear phase of the ideal straight line.

[0140] In this embodiment, the ideal straight line is a straight line passing through the first phase point and the last phase point of the non-winding phase. The linear phase of the ideal straight line is determined based on the first phase point and the last phase point of the non-winding phase; the nonlinear correction data is determined based on the phase difference between the non-winding phase of the glass surface interference pattern and the linear phase of the ideal straight line, which can effectively identify the phase nonlinearity generated by the interference pattern, improve the accuracy of the nonlinear correction data, and facilitate the subsequent system to correct the phase nonlinearity and compensate for dispersion of the collected interference pattern based on the nonlinear correction data, thereby improving the accuracy of the interference signal, and improving the precision and quality of imaging.

[0141] In one embodiment, if Figure 5 As shown, in step S30, phase correction is performed on the interference pattern of the target object based on the nonlinear correction data, and a reconstructed image of the target object is obtained based on the corrected interference pattern, which specifically includes the following steps:

[0142] S31: Optimizing the window function used in the image reconstruction process based on the nonlinear correction data to obtain an improved correction filter function.

[0143] During the operation of the optical imaging system, after obtaining the nonlinear correction data, the image processing device can determine the window function used by the current system in the image reconstruction process, and optimize the window function used in the image reconstruction process based on the nonlinear correction data to obtain an improved correction filter function.

[0144] The improved correction filter function is obtained by directly multiplying the nonlinear correction data with the window function, that is, the improved correction filter function can be determined by the formula:

[0145] F(t) = H(t)·C(t);

[0146] Among them, F(t) represents the improved correction filter function; H(t) represents the window function used in the image reconstruction process, such as the Hanning window function; C(t) represents the nonlinear correction data, that is, the nonlinear correction factor that changes with time.

[0147] Among them, the window function H(t) can improve the smoothness of the spectrum edge signal of the interference pattern and reduce the amplitude fluctuation of the signal at the boundary; the nonlinear correction data C(t) is used to perform nonlinear compensation on the wave number of the interference pattern.

[0148] S32: performing interference signal correction processing on the interference pattern of the target object according to the correction filter function, and performing image reconstruction according to the corrected interference pattern to obtain a reconstructed image of the target object.

[0149] The interference signal correction processing is performed on the interference pattern of the target object according to the improved correction filter function, and the image is reconstructed according to the corrected interference pattern to obtain a reconstructed image of the target object.

[0150] The improved correction filter function is obtained by combining nonlinear correction data and window function. The window function H(t) can improve the smoothness of the spectrum edge signal of the interference pattern and reduce the amplitude fluctuation of the signal at the boundary; the nonlinear correction data C(t) is used to perform nonlinear compensation on the wave number of the interference pattern.

[0151] Dispersion refers to the fact that light of different wavelengths (wave numbers) is delayed to varying degrees during propagation due to the frequency dependence of the medium, which causes the relationship between the phase and the wave number to be nonlinear. If the signal is not dispersed, the phase φ(k) of the light should be linearly related to the wave number k, such as: φ(k) = m·k+b; but when the signal is dispersed, dispersion will cause different phase delays in different parts of the spectrum, thereby introducing time broadening f(k) after Fourier transform and reducing the imaging resolution. At this time, the relationship between the phase of the light and the wave number k becomes a nonlinear curve, which can usually be expressed as: φ(k) = m·k+b+f(k), where m and b are constant values; therefore, we find that the nonlinear phase delay introduced by dispersion is also included in the phase difference δ k middle.

[0152] The improved correction filter function is applied to the frequency domain signal correction of the interference signal. Its advantage is that wavenumber linearization processing can be achieved without using complex interpolation methods. It can correct wavenumber nonlinearity and dispersion effects at the same time, improve image reconstruction quality and efficiency, and provide a basis for real-time image reconstruction.

[0153] In this embodiment, the window function used in the image reconstruction process is optimized based on the nonlinear correction data to obtain an improved correction filter function, and then the interference signal correction processing is performed on the interference pattern of the target object according to the improved correction filter function, and the image is reconstructed according to the corrected interference pattern to obtain a reconstructed image of the target object; the window function is optimized and improved based on the nonlinear correction data, and the interference signal is corrected by the improved correction filter function, which not only makes the signal smoother and reduces the distortion caused by the nonlinearity, noise or system error of the signal, but also improves the restoration of details in the image reconstruction process, improves the image quality, and enables the image reconstruction to maintain stability and efficiency in different application scenarios.

[0154] In one embodiment, step S32, namely, performing interference signal correction processing on the interference pattern of the target object according to the correction filter function, and performing image reconstruction according to the corrected interference pattern to obtain a reconstructed image of the target object, specifically includes the following steps:

[0155] S321: Perform DC signal removal processing on the interference pattern of the target object to obtain an effective interference signal.

[0156] As mentioned above, the interference pattern of the target object collected by the system includes two parts: DC signal and interference signal. The interference signal of the interference pattern of the target object can be expressed by the following formula:

[0157]

[0158] Among them, I Acq The interference signal representing the interference pattern (expressed as light intensity); I ref +I samp The DC signal representing the interference pattern does not include phase information; I ref Represents the signal formed by the reference arm in the optical system, I samp Indicates the signal formed by the sample arm in the optical system; Indicates; I samp1 represents the object collection signal formed by the sample arm in the optical system; p 1 Represents the relative phase change caused by the optical path difference between the reference arm and the sample arm. The optical path difference between the reference arm and the sample arm determines the phase characteristics of the interference signal.

[0159] In order to extract effective interference signals, the image processing device can remove the DC signal from the collected interference pattern of the target object to obtain a clean interference signal after isolating the DC signal, that is, to obtain an effective interference signal after removing the DC signal. By removing the DC component from the collected interference pattern, low-frequency noise can be eliminated and the effective part of the interference signal can be extracted to improve the accuracy of subsequent signal processing and extraction.

[0160] S322: Perform Fourier transform on the effective interference signal, and perform inverse Fourier transform on the frequency domain signal after the Fourier transform to obtain a filtered time domain signal.

[0161] After obtaining the effective interference signal, the image processing device performs Fourier transform on the effective interference signal after removing the DC signal, and can filter out the interference signal of noise or low-frequency components in the frequency domain to obtain the frequency domain signal after Fourier transform, and perform signal isolation on the frequency domain signal after Fourier transform, that is, smooth out the clutter around the peak of the frequency domain signal after Fourier transform, and extract the optimized frequency domain signal; then perform inverse Fourier transform on the optimized frequency domain signal, so that the frequency domain signal returns to the time domain, and obtains the filtered time domain signal, thereby improving the accuracy of the time domain signal.

[0162] S323: Perform nonlinear correction and dispersion compensation on the filtered time domain signal using a correction filter function to obtain a corrected interference signal.

[0163] The image processing device uses the correction filter function to perform nonlinear correction and dispersion compensation on the filtered time domain signal to obtain a corrected interference signal. The corrected interference signal is determined by the following formula:

[0164] I c (t) = I r (t)·F(t);

[0165] F(t) = H(t)·C(t);

[0166] Among them, I c (t) represents the correction interference signal; I r (t) represents the time domain signal after filtering; F(t) represents the correction filter function; H(t) represents the window function used in the image reconstruction process, such as the Hanning window function; C(t) represents the nonlinear correction data, that is, the nonlinear correction factor that changes with time.

[0167] S324: Reconstruct an image of the target object based on the corrected interference signal to obtain a reconstructed image of the target object.

[0168] After obtaining the corrected interference signal of the interference pattern, the image processing device reconstructs the image of the target object based on the corrected interference signal to obtain a reconstructed image of the target object. The corrected interference signal can be Fourier transformed to obtain a corrected frequency domain signal, and then the image of the target object is reconstructed according to the corrected frequency domain signal to obtain a reconstructed image of the target object.

[0169] Among them, taking the optical imaging system as SSOCT as an example, its image reconstruction method is scanning image reconstruction, then the image of the target object is reconstructed based on the correction interference signal to obtain a reconstructed image of the target object, which specifically includes the following steps:

[0170] S3241: Perform Fourier transform on the correction interference signal to obtain a correction frequency domain signal.

[0171] Among them, the transformation formula for correcting the frequency domain signal is expressed as follows:

[0172]

[0173] Among them, F c (ω) represents the corrected frequency domain signal; I c (t) represents the correction interference signal; represents Fourier transform.

[0174] S3242: Map the horizontal axis of the corrected frequency domain signal to a depth position, and determine the depth information of the target object based on the corrected frequency domain signal.

[0175] The image processing device converts the corrected frequency domain signal into the depth information of the target sample according to the refractive index and light speed of the storage medium (such as water or air) of the target object. The depth information represents the signal intensity distribution of the target object in the depth direction. The process of acquiring the information of the depth of the target sample is expressed by the following formula:

[0176] A(z)=|F c (ω)|;

[0177]

[0178] Where A(z) represents the depth information of the target object, that is, the signal intensity distribution of the target object in the depth direction (that is, the image brightness information); F c (ω) represents the amplitude of the corrected frequency domain signal; z represents the depth of the target object, that is, the distance from the surface of the target object to the signal acquisition area; n represents the refractive index of the storage medium of the target object; c represents the speed of light; Δf represents the frequency change of the light source.

[0179] S3243: According to the depth information of the target object, the optical system is controlled to perform a frequency sweep image scan, and a longitudinal section image of the target object is reconstructed to generate a reconstructed image of the target object.

[0180] After obtaining the depth information of the target object, the image processing device controls the movement of the galvanometer of the sample arm in the optical system according to the depth information of the target object, so as to focus the light beam of the sample arm to the depth position, perform frequency sweep image scanning, that is, scan in a line segment manner, obtain multiple different point scanning images, and combine the multiple different point scanning images into a longitudinal section image of the target object. The longitudinal section image can be directly output as a reconstructed image of the target object.

[0181] In other embodiments, after obtaining the longitudinal section image of the target object, the movement of the moving stage in the optical imaging system can be controlled to scan different surfaces of the target object to obtain surface images, and the three-dimensional image of the target object can be reconstructed in combination with the longitudinal section image and output as the reconstructed image of the target object.

[0182] In this embodiment, the interference pattern of the target object is subjected to DC signal removal processing to obtain an effective interference signal; the effective interference signal is subjected to Fourier transform, and the frequency domain signal after the Fourier transform is subjected to inverse Fourier transform to obtain a filtered time domain signal; the filtered time domain signal is subjected to nonlinear correction and dispersion compensation using a correction filter function to obtain a corrected interference signal; the image of the target object is reconstructed based on the corrected interference signal to obtain a reconstructed image of the target object, and by performing a series of optimization processing, nonlinear correction and dispersion compensation on the signal, the corrected interference signal is finally obtained for image reconstruction, thereby improving the quality and efficiency of image reconstruction.

[0183] In a specific embodiment, Figure 6 As shown, the image processing device obtains the interference pattern of the glass surface, removes the DC signal of the interference pattern of the glass surface, and performs Fourier transformation on the interference signal after the DC removal, and performs signal isolation on the Fourier transformed signal to remove clutter, and obtains a clean target frequency domain signal, and then performs inverse Fourier transformation on the clean target frequency domain signal to obtain an effective time domain signal; then, the effective time domain signal is Hilbert transformed to obtain a target analytical signal after the effective time domain signal is extended, and the target analytical signal is non-entangled to obtain the non-entangled phase of the glass surface interference pattern, and finally the nonlinear phase difference between the non-entangled phase and the linear phase of the ideal straight line is determined, and nonlinear correction data is generated according to the nonlinear phase difference. After obtaining the interference pattern of the target object, the DC signal of the interference pattern of the target object is removed to obtain an effective interference signal; the nonlinear correction data is called to optimize the window function used in the image reconstruction process to obtain an improved correction filter function, and the effective interference signal is corrected by using the improved correction filter function to obtain a corrected interference signal, and the corrected interference signal is Fourier transformed to obtain a corrected frequency domain signal, so as to reconstruct the image based on the corrected frequency domain signal.

[0184] Among them, the image reconstruction process is performed based on the corrected frequency domain signal, such as Figure 7 As shown, the image processing device performs depth position mapping on the horizontal axis of the corrected frequency domain signal, and determines the depth information A of the target object based on the corrected frequency domain signal, where the depth information represents the signal strength of the target object in the depth direction. Then, based on the depth information A of the target object, the optical system is controlled to perform frequency sweep image scanning, and a longitudinal section image B of the target object is reconstructed. Finally, the movement of the moving stage in the optical imaging system is controlled to scan different surfaces of the target object to obtain a surface image, and the three-dimensional image C of the target object is reconstructed in combination with the longitudinal section image, and outputted as a reconstructed image of the target object.

[0185] In this embodiment, the nonlinear phase difference is obtained in advance through the interference pattern of the glass surface, and the improved correction filter function is obtained by optimizing the window function. The improved correction filter function is used to perform phase correction on the frequency domain information, which can accurately correct the nonlinear components in the interference signal, make the signal smoother, reduce the distortion caused by the nonlinearity, noise or system error of the signal, improve the restoration of details in the image reconstruction process, and improve the quality and efficiency of image reconstruction.

[0186] It should be understood that the order of execution of the steps in the above embodiment does not necessarily mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiment of the present invention.

[0187] In one embodiment, an image processing device is provided, which corresponds one-to-one to the phase correction method for optical imaging in the above embodiment. Figure 8 As shown, the image processing device includes an acquisition module 801, a control module 802 and a reconstruction module 803. The detailed description of each functional module is as follows:

[0188] An acquisition module 801 is used to acquire nonlinear correction data, where the nonlinear correction data is a phase correction array obtained by performing non-entanglement phase extraction on a glass surface interference pattern collected by an optical imaging system in advance, and performing nonlinear phase correction;

[0189] A control module 802 is used to control the optical imaging system to collect interference patterns of the target object to obtain interference patterns of the target object;

[0190] The reconstruction module 803 is used to perform phase correction on the interference pattern of the target object based on the nonlinear correction data during the image reconstruction process, and reconstruct the reconstructed image of the target object based on the corrected interference pattern.

[0191] Optionally, the reconstruction module 803 is specifically used for:

[0192] The window function used in the image reconstruction process is optimized based on the nonlinear correction data to obtain an improved correction filter function;

[0193] The interference signal correction processing is performed on the interference pattern of the target object according to the correction filter function, and the image is reconstructed according to the corrected interference pattern to obtain a reconstructed image of the target object.

[0194] Optionally, the reconstruction module 803 is further configured to:

[0195] Perform DC signal removal processing on the interference pattern of the target object to obtain an effective interference signal;

[0196] Performing Fourier transform on the effective interference signal, and performing inverse Fourier transform on the frequency domain signal after Fourier transform to obtain a filtered time domain signal;

[0197] The correction filter function is used to perform nonlinear correction and dispersion compensation on the filtered time domain signal to obtain a correction interference signal;

[0198] An image of the target object is reconstructed based on the corrected interference signal to obtain a reconstructed image of the target object.

[0199] Optionally, the image processing apparatus further includes a determining module 804, and the determining module 804 is used to:

[0200] Controlling the optical imaging system to collect interference patterns on the glass surface to obtain interference patterns on the glass surface;

[0201] Perform effective signal extraction on the collected glass surface interference pattern to obtain an effective time domain signal of the glass surface interference pattern;

[0202] Performing Hilbert transform on the effective time domain signal to obtain the target analytical signal, and performing non-entanglement phase extraction on the target analytical signal to obtain the non-entanglement phase of the glass surface interference pattern;

[0203] The linear phase difference between the non-winding phase and the ideal straight line of the interference pattern on the glass surface is determined to obtain nonlinear correction data, and the ideal straight line is a straight line determined according to the non-winding phase.

[0204] It should be noted that the information interaction, execution process, etc. between the above-mentioned devices / units are based on the same concept as the method embodiment of the present application. Their specific functions and technical effects can be found in the method embodiment part and will not be repeated here.

[0205] The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0206] The present application also provides an electronic device, such as Fig. 9 As shown, the electronic device includes: at least one processor, a memory, and a computer program stored in the memory and executable on the at least one processor, wherein the processor implements the steps in any of the above-mentioned method embodiments when executing the computer program, or implements the functions of the modules / units in the above-mentioned device embodiments when executing the computer program.

[0207] Exemplarily, the computer program may be divided into one or more modules / units, which are stored in the memory and executed by the processor to complete the present application. The one or more modules / units may be a series of computer program instruction segments capable of completing specific functions, which are used to describe the execution process of the computer program in the electronic device.

[0208] Those skilled in the art will understand that Fig. 9 These are merely examples of the electronic device and do not constitute a limitation of the electronic device. The electronic device may include more or fewer components than those shown in the figure, or a combination of certain components, or different components. For example, the electronic device may also include input and output devices, network access devices, buses, etc.

[0209] The processor may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor, etc.

[0210] The memory may be an internal storage unit of the electronic device, such as a hard disk or memory of the electronic device. The memory may also be an external storage device of the electronic device, such as a plug-in hard disk, a smart memory card (Smart Media Card, SMC), a secure digital (Secure Digital, SD) card, a flash card (Flash Card), etc. equipped on the electronic device. Furthermore, the memory may also include both an internal storage unit of the electronic device and an external storage device.

[0211] An embodiment of the present application further provides a readable storage medium, wherein the readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps in the above-mentioned method embodiments can be implemented.

[0212] An embodiment of the present application provides a computer program product. When the computer program product runs on an electronic device, the electronic device can implement the steps in the above-mentioned method embodiments when executing the computer program product.

[0213] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present application implements all or part of the processes in the above-mentioned embodiment method, which can be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and the computer program can implement the steps of the above-mentioned various method embodiments when executed by the processor. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium can at least include: any entity or device that can carry the computer program code to the camera / terminal device, recording medium, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, RandomAccess Memory), electric carrier signal, telecommunication signal and software distribution medium. For example, a USB flash drive, a mobile hard disk, a magnetic disk or an optical disk. In some jurisdictions, according to legislation and patent practice, computer-readable media cannot be electric carrier signals and telecommunication signals.

[0214] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0215] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0216] In the embodiments provided in the present application, it should be understood that the disclosed devices / equipment and methods can be implemented in other ways. For example, the device / equipment embodiments described above are merely schematic, for example, the division of the modules or units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of devices or units, which can be electrical, mechanical or other forms.

[0217] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0218] The embodiments described above are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, a person skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application, and should all be included in the protection scope of the present application.

Claims

1. A phase correction method for optical imaging, characterized in that: include: Acquire nonlinear correction data, wherein the nonlinear correction data is a phase correction array obtained by performing non-entanglement phase extraction on a glass surface interference pattern collected by an optical imaging system in advance, and performing nonlinear phase correction; Controlling the optical imaging system to collect interference patterns of the target object to obtain the interference patterns of the target object; During the image reconstruction process, the interference pattern of the target object is phase corrected based on the nonlinear correction data, and a reconstructed image of the target object is obtained based on the corrected interference pattern.

2. The phase correction method for optical imaging according to claim 1, characterized in that: The performing phase correction on the interference pattern of the target object based on the nonlinear correction data, and reconstructing the reconstructed image of the target object based on the corrected interference pattern, comprises: Optimizing the window function used in the image reconstruction process based on the nonlinear correction data to obtain an improved correction filter function; The interference signal correction process is performed on the interference pattern of the target object according to the correction filter function, and image reconstruction is performed according to the corrected interference pattern to obtain a reconstructed image of the target object.

3. The phase correction method for optical imaging according to claim 2, characterized in that: The step of performing interference signal correction processing on the interference pattern of the target object according to the correction filter function, and performing image reconstruction according to the corrected interference pattern to obtain a reconstructed image of the target object includes: Performing DC signal removal processing on the interference pattern of the target object to obtain an effective interference signal; Performing Fourier transform on the effective interference signal, and performing inverse Fourier transform on the frequency domain signal after the Fourier transform to obtain a filtered time domain signal; Using the correction filter function to perform nonlinear correction and dispersion compensation on the filtered time domain signal to obtain a corrected interference signal; An image of the target object is reconstructed based on the corrected interference signal to obtain a reconstructed image of the target object.

4. The phase correction method for optical imaging according to any one of claims 1 to 3, characterized in that: The nonlinear correction data is determined by: Controlling the optical imaging system to collect interference patterns on the glass surface to obtain the interference patterns on the glass surface; Performing effective signal extraction on the collected glass surface interference pattern to obtain an effective time domain signal of the glass surface interference pattern; Performing Hilbert transform on the effective time domain signal to obtain a target analytical signal, and performing non-entanglement phase extraction on the target analytical signal to obtain a non-entanglement phase of the glass surface interference pattern; The linear phase difference between the non-winding phase of the glass surface interference pattern and an ideal straight line is determined to obtain the non-linear correction data, wherein the ideal straight line is a straight line determined according to the non-winding phase.

5. The phase correction method for optical imaging according to claim 4, characterized in that: The step of performing Hilbert transform on the effective time domain signal to obtain a target analytical signal, and performing non-entanglement phase extraction on the target analytical signal to obtain the non-entanglement phase of the glass surface interference pattern comprises: Performing Hilbert transform on the effective time domain signal to obtain a target analytical signal after expanding the effective time domain signal; Performing phase analysis on the target analysis signal to extract the instantaneous phase of the interference pattern on the glass surface; The instantaneous phase of the interference pattern on the glass surface is subjected to non-wrapping phase processing to obtain a non-wrapping phase with a continuous phase distribution in the interference pattern on the glass surface.

6. The phase correction method for optical imaging according to claim 4, characterized in that: The extracting effective signals from the collected glass surface interference pattern to obtain effective time domain signals of the glass surface interference pattern comprises: Performing direct current signal removal on the collected interference pattern of the glass surface, and performing Fourier transform and signal isolation on the interference signal after the direct current signal is removed, to obtain a target frequency domain signal; The target frequency domain signal is subjected to inverse Fourier transform to obtain an effective time domain signal of the glass surface interference pattern.

7. An image processing device, characterized in that: include: An acquisition module, used for acquiring nonlinear correction data, wherein the nonlinear correction data is a phase correction array obtained by performing non-entanglement phase extraction on a glass surface interference pattern collected by an optical imaging system in advance, and nonlinear phase correction; A control module, used to control the optical imaging system to collect interference patterns of the target object to obtain the interference patterns of the target object; A reconstruction module is used to perform phase correction on the interference pattern of the target object based on the nonlinear correction data during image reconstruction, and reconstruct a reconstructed image of the target object based on the corrected interference pattern.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the steps of the phase correction method for optical imaging according to any one of claims 1 to 6 are implemented.

9. A readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the steps of the phase correction method for optical imaging according to any one of claims 1 to 6 are implemented.

10. A computer program product, characterized in that The computer program product comprises a computer program, which, when executed by a processor, enables implementation of the steps of the phase correction method for optical imaging according to any one of claims 1 to 6.

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