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CN118806237B - Ultra-deep three-dimensional imaging device and method based on swept frequency optical coherence tomography in turbid media - Google Patents

Ultra-deep three-dimensional imaging device and method based on swept frequency optical coherence tomography in turbid media Download PDF

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CN118806237B
CN118806237B CN202410875182.0A CN202410875182A CN118806237B CN 118806237 B CN118806237 B CN 118806237B CN 202410875182 A CN202410875182 A CN 202410875182A CN 118806237 B CN118806237 B CN 118806237B
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丁志华
杨璐
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Zhejiang University ZJU
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Abstract

The invention discloses an ultra-deep three-dimensional imaging device and method based on a sweep-frequency optical coherence tomography technology in a turbid medium. The invention utilizes the three-dimensional scattered field rapid detection method combining the parallel detection of the sample in the depth direction and the scanning detection of the transverse field distribution to obtain the depth-resolved reflection matrix and provide the depth range required by ultra-deep imaging. The invention acquires and compensates inherent intra-frame phase fluctuation of scanning detection by introducing a quasi-common reference arm into the system, and realizes image reconstruction by adopting a matrix method insensitive to residual inter-frame phase drift. The residual uncompensated interframe direct current drift and the uniform phase distribution error have no influence on image reconstruction, and the total measurement time of ultra-deep three-dimensional imaging (125 micrometers multiplied by 4 millimeters) realized by the method is about 5 minutes, so that the method has obvious leap compared with a time domain matrix method.

Description

Ultra-deep three-dimensional imaging device and method based on sweep-frequency optical coherence tomography in turbid medium
Technical Field
The invention belongs to the field of ultra-deep imaging in a strong scattering medium, and particularly relates to an ultra-deep three-dimensional imaging device and method based on a sweep-frequency optical coherence tomography technology in a turbid medium.
Background
Light scattering is not only an information source for optical imaging of biological tissues, but also a limiting factor for optical imaging of deep tissues. Biological tissue may be described as a non-uniform, strongly scattering medium in which light propagates through it, subject to light scattering due to spatial fluctuations in refractive index. Unfortunately, as the depth of light propagation increases, the number of singly scattered photons decays rapidly exponentially, while the number of multiply scattered photons increases with depth, the target information carried by singly scattered photons returned from the sample has been difficult to recover, making the penetration depth achievable with conventional imaging techniques based on singly scattered photons extremely shallow. The conventional focusing and imaging method under the existing born approximation is only effective under the transparent or weak scattering condition and cannot be applied to focusing and imaging under the strong scattering condition. Therefore, the problems of light transmission and imaging in biological tissues, especially deep tissue optical imaging, are a fundamental problem and a scientific problem to be solved urgently.
In order to realize deep high resolution imaging of biological tissues, many scholars have proposed effective solutions, such as using long wavelength imaging or tissue light transparent technology to reduce scattering coefficient of biological tissues, reduce multiple scattering of light in biological tissues, or forming back-diffused wavefront based on time-reversal wave front shaping technology to resist the influence of multiple scattering and distortion on beam focusing and imaging. The most sophisticated method to date to eliminate multiple scattered light is optical coherence tomography (Optical coherencetomography, OCT). As a non-invasive, non-contact, label-free and low-cost real-time optical imaging method, OCT comprehensively utilizes two gating technologies of a space gate and a time gate, can effectively separate single scattered light from a multi-scattering background, and can construct a high-resolution image according to the single scattered light. However, due to the influence of strong scattering in biological tissues, the imaging depth of OCT in biological tissues is still limited to about 1-2mm, and in order to further exert the advantages of OCT, the imaging depth limitation needs to be broken through.
The AlexandreAubry team of the French Langmuir institute firstly proposes a time domain OCT system based on a reflection matrix, and is expected to realize at least 2 times of imaging depth expansion. The basic mechanisms for reducing multiple scattered photons and enhancing single scattered photons include wide field detection of complex scattered fields and iterative time reversal based image reconstruction. In matrix OCT methods it is important to measure the backscattered complex amplitude field accurately and rapidly, phase shifting is a common method of obtaining complex amplitude fields, but phase shifting by mechanical motion is both time consuming and unstable. In order to increase the measurement speed of the reflection matrix, chen Zhongping group proposed a wide-field heterodyne detection method based on an acousto-optic modulator and a phase-locked camera, but the complexity and cost of the system are increased accordingly. As is well known, swept OCT (SS-OCT) performs better than time domain OCT, however, matrix OCT schemes reported so far are all based on time domain OCT systems, where only one depth-corresponding reflection matrix can be measured at a time and then used for two-dimensional image reconstruction, three-dimensional (3D) ultra-deep OCT imaging has not been demonstrated.
Disclosure of Invention
The invention provides an ultra-deep three-dimensional imaging device and method based on sweep frequency optical coherence tomography in a turbid medium, which are realized by the following technical scheme:
The ultra-deep three-dimensional imaging device based on the sweep optical coherence tomography in a turbid medium comprises a high-speed sweep light source, a Mach-Zehnder interferometer clock box, a coupler A, an interferometer comprising a sample arm and a reference arm, a coupler B, a balance detector and a computer for processing data, wherein the high-speed sweep light source, the Mach-Zehnder interferometer clock box, the coupler A, the interferometer comprising the sample arm and the reference arm, the reference arm comprises a collimating lens A and a focusing lens A, the sample arm comprises the collimating lens B, a beam splitter, the focusing lens B and a sample which are sequentially connected, a focusing lens C and a reference mirror which are sequentially connected with one side of the beam splitter, a biaxial vibrating mirror A and a collimating lens C which are sequentially connected with the other side of the beam splitter, the input end of the sample arm is connected with the coupler A through the collimating lens B, and the output end of the sample arm further comprises a biaxial vibrating mirror B arranged between the collimating lens B and the beam splitter or a biaxial displacement platform which is arranged on the bottom surface of the sample and supports the sample.
As a further improvement, the biaxial displacement platform is used for realizing focusing light scanning by moving a sample, or a biaxial vibrating mirror B is arranged at the input end of a sample arm and used for scanning incident light.
As a further improvement, the reference reflector is arranged at the defocusing position of the front focusing lens C, and the position depth of the reference reflector and the position depth of the upper surface of the sample are ensured to form a similar but distinguishable quasi-common path.
As a further improvement, the effective scanning range of the biaxial vibrating mirror A is required to be consistent with the range of the imaging area of the sample.
The invention also discloses an ultra-deep three-dimensional imaging method based on the ultra-deep three-dimensional imaging device based on the sweep frequency optical coherence tomography in the turbid medium, which comprises the following steps:
the sample is moved by adopting a biaxial displacement platform or the incident light is scanned by utilizing a biaxial galvanometer B at the input end of a sample arm so as to realize the traversing scanning of the focused light on each position of the sample;
at each focusing light scanning position, scanning and detecting and recording interference spectrum signals of the corresponding three-dimensional back scattering field by utilizing a biaxial vibrating mirror A;
performing inverse Fourier transform on the detected spectrum signals to obtain complex amplitude signals of the three-dimensional back-scattered field from the sample and the reference reflector;
according to the clock signal output by the Mach-Zehnder interferometer clock box, calculating phase errors caused by wavelength changes between different axial scanning detection, and compensating for corresponding axial scanning signals in the three-dimensional back-scattered field;
According to complex amplitude fields of the reference reflector obtained by multiple measurements (corresponding to different positions of the focused light scanning), calculating the interframe change of the light field distribution of the complex amplitude fields, and further compensating the complex amplitude fields to the corresponding three-dimensional backward scattering fields;
after the phase compensation operation is finished, uncompensated phases still remain, but the subsequent image reconstruction is not affected;
rearranging two-dimensional fields with the same depth in all the three-dimensional backscattering fields after phase compensation into column vectors, and arranging the column vectors in a reflection matrix according to a scanning track, thereby forming a reflection matrix with a specified depth;
the remolding process is carried out on two-dimensional fields with different depths in the three-dimensional back scattering complex field, and a depth-resolved reflection matrix is constructed;
Filtering most of multiple scattering contributions from the reflection matrix of each depth by adopting a digital pinhole, and then carrying out singular value decomposition and two-dimensional image reconstruction;
In the image reconstruction, in order to determine the number of required main singular values, correlation analysis is carried out on image pairs formed by images reconstructed by different numbers of singular values and images reconstructed by corresponding residual singular values, so as to determine the number of optimal main singular values and realize the optimal reconstruction of a two-dimensional image;
finally, arranging the best reconstructed two-dimensional image obtained by each depth according to the depth, so that a successfully recovered three-dimensional target can be obtained, and ultra-deep imaging in the turbid medium can be realized.
As a further improvement, the phase error of the present invention includes that the device has phase errors caused by various interference factors, including wavelength shift between axial scans, mechanical jitter of the dual-axis galvanometer a, optical path mismatch, etc., and the phase errors can be divided into intra-frame phase fluctuation and inter-frame phase drift according to different change rates: wherein x and y are respectively orthogonal coordinates of the back-scattered field, z is the corresponding depth of the sample signal, Scanning a location for a sample;
According to the different sample scanning modes, when the device adopts a mode of scanning incident light by the biaxial galvanometer B, the incident light can undergo spatially-varying aberration, thereby causing additional intra-frame phase fluctuation, and when the device adopts a displacement platform to move the sample, the incident light is fixed and cannot undergo spatially-varying aberration.
As a further improvement, according to the clock signal output by the Mach-Zehnder interferometer clock box, the phase error caused by wavelength variation between different axial scanning detection is calculated, and the phase error is compensated to the corresponding axial scanning signal in the three-dimensional back-scattered field, which comprises the following steps:
Calculating the phase difference after the Hilbert transform of the reference signal output by the Mach-Zehnder interferometer clock box, and performing a first-step phase compensation operation:
Where z MZI is the corresponding depth of the clock signal, For the hilbert phase difference between the interference signals generated by the mach-zehnder interferometer clock bins,AndThe phase distribution of the original and first phase compensated sample signal, respectively.
As a further improvement, the complex amplitude field of the reference mirror obtained according to the multiple measurements (corresponding to the scanning of the focused light at different positions) of the present invention calculates the inter-frame variation of the light field distribution thereof, and further compensates for the corresponding three-dimensional back-scattered field, including:
Calculating the inter-frame phase difference of the light field of a reference mirror The phase distribution of each frame compensated to the sample signal is aimed at unifying the scanning errors of inconsistent distribution among all fields of the sample signal into one same phase distribution error, and the phase compensation process is described as follows:
Where z R is the depth of the reference mirror signal, E R is normalized by E R＝ER0/|ER0 |, E R0 is the backscattered light field from the reference mirror, Is the phase distribution of the sample signal that is ultimately phase compensated.
As a further improvement, the phase compensation operation of the present invention is completed with uncompensated phase remaining but without affecting the subsequent image reconstruction, comprising the steps of: Wherein the method comprises the steps of For introducing specific phase distribution errors (abbreviated as),For inter-frame phase drift (dc quantity independent of background distribution), the reflection matrix R e can be expressed as:
Where R is an ideal reflection matrix with no phase error, D is an error matrix composed of phase distribution errors of the reference frame, and E is an error matrix composed of inter-frame phase fluctuations. The process of decomposition of the reflection matrix and reconstruction of the image is as follows:
Are all time-reversal operators, and the singular value decomposition of matrix R can be expressed as Represents the conjugate transpose, U and V are unitary matrices, Σ is a diagonal matrix composed of a descending arrangement of singular values (positive real numbers) σ i (i { i e [1, N ] }), and the matrix U d =DU represents that the matrix U is weighted by a phase-only diagonal matrix D, the matrixRepresenting matrix V by a phase-only diagonal matrixWeighting; And Is a two-dimensional wavefront reshaped by the column vector U i、Vi of matrix U, V, and M (M < N) is the optimal number of singular values for reconstruction. Therefore, the background phase change irrelevant to distribution has no influence on image reconstruction, namely the image reconstruction is insensitive to inter-frame phase drift, the uniform phase distribution error has no influence on the image reconstruction, and the post-processing and the image reconstruction of a reflection matrix formed by the compensated complex scattered field are not influenced by the scanning detection of the device.
Based on the technical scheme, the invention has the following beneficial effects compared with the prior art:
1. Compared with the prior art, the method utilizes the method of combining parallel detection in the depth direction of the sample and scanning detection of transverse field distribution to realize rapid detection of the three-dimensional scattering field, so that the measurement of the three-dimensional reflection matrix and the three-dimensional ultra-deep imaging process are more efficient and accurate. The invention adopts a scanning detection mechanism, and a high-speed sweep-frequency light source and a matched high-speed point detector are used in the system to provide a sufficient depth range for ultra-deep imaging.
2. Compared with the existing reflection matrix measurement technology, the measurement system provided by the invention is simple in arrangement and low in cost, only needs to increase the scanning detection for transverse field distribution and the measurement of a reference signal for phase compensation on the basis of the traditional scanning optical chromatography system, and the system can be directly switched to the traditional scanning optical chromatography system by fixing the position of the biaxial galvanometer at the detection end of the sample arm at the center.
3. The method provided by the invention comprehensively researches the influence of phase interference caused by scanning detection on an optical coherence tomography method based on matrix measurement in the backward scattered field measurement process for the first time, and comprises intra-frame and inter-frame phase fluctuation. The invention introduces Mach-Zehnder interferometer to generate clock signal, and places reference mirror (using half of the originally wasted incident light) at the other end of beam splitter in sample arm to generate quasi-common reference signal, and compensates phase fluctuation in frame together, and the phase error of inconsistent distribution among all fields after compensation is unified into one same specific distribution error. The method proves that the matrix method is insensitive to residual interframe phase drift and uniform phase distribution errors, and image reconstruction is not influenced by system scanning detection.
4. The invention realizes three-dimensional ultra-depth optical coherence tomography in turbid medium for the first time, the total measurement time of the ultra-depth three-dimensional imaging (125 micrometers multiplied by 4 millimeters) system realized by the invention is about 5 minutes, compared with time domain matrix OCT, the time domain matrix OCT has obvious leap, and the two-dimensional target imaging with a specified depth can be completed only in 6 minutes.
Drawings
FIG. 1 is a system diagram of an ultra-deep three-dimensional imaging device based on a swept-frequency optical coherence tomography technology;
FIG. 2 is a process flow diagram of an ultra-deep three-dimensional imaging method based on swept-frequency optical coherence tomography in turbid media according to the invention;
FIG. 3 is a schematic diagram of the phase compensation result in the present invention, wherein the mirror is used as a sample to continuously measure the backward scattered field, the first three columns in FIG. a are the phase distributions of the scattered field at three different sample positions, and the second two columns are the phase differences to indicate whether the phase error is completely compensated, and the uncompensated phase in FIG. b is the inter-frame phase, which increases with the increase of the measurement time;
Fig. 4 is a representation of the results of the present invention for ultra-deep imaging in scattering media, the second and third columns of fig. a are the reconstruction results obtained by conventional SS-OCT and matrix SS-OCT, respectively, fig. b is an enlarged view of the three-dimensional structure of the last three microspheres (identified as 8, 9, 10) near the maximum depth shown by the dashed rectangle in fig. a, and fig. c is a two-dimensional image of the three microspheres and a normalized intensity contrast plot of the light intensity distribution at their centroid.
In the figure, 1, a high-speed sweep light source, 2, a Mach-Zehnder interferometer clock box, 3, a coupler A,4, a collimating lens A,5, a focusing lens A,6, a polarization controller, 7, a collimating lens B,8, a beam splitter, 9, a focusing lens B,10, a sample, 11, a focusing lens C, 12, a reference reflector, 13, a biaxial vibrating mirror A,14, a collimating lens C,15, a biaxial displacement platform, 16, a coupler B,17, a balance detector, 18, a computer, 19 and a biaxial vibrating mirror B are shown in the specification.
Detailed Description
The invention is further described below with reference to the drawings and examples.
FIG. 1 is a system diagram of an ultra-deep three-dimensional imaging device based on a sweep optical coherence tomography technology in a turbid medium, the ultra-deep three-dimensional imaging device based on the sweep optical coherence tomography technology in the turbid medium comprises a high-speed sweep light source (1), a Mach-Zehnder interferometer clock box (2), a coupler A (3), an interferometer comprising a sample arm and a reference arm, a coupler B (16), a balance detector (17) and a computer (18) for processing data, wherein the reference arm comprises a collimating lens A (4) and a focusing lens A (5), the sample arm comprises a collimating lens B (7), a beam splitter (8), a focusing lens B (9) and a sample (10) which are sequentially connected, a focusing lens C (11) and a reference mirror (12) which are sequentially connected on one side of the beam splitter (8), a biaxial vibrating mirror A (13) and a collimating lens C (14) which are sequentially connected on the other side, the input end of the sample arm is connected with the coupler A (3) through the collimating lens B (7), the output end of the sample arm is connected with the collimating lens B (14) through the collimating lens B (16) and the sample arm is arranged between the sample arm (8) and the sample (8) or a sample (19) which comprises a collimating lens B and a sample shaft (19) which is also arranged between the sample shaft and the sample shaft (8).
In the sample arm, incident light is divided into a transmission light beam and a reflection light beam after passing through a beam splitter (8), a focusing lens B (9) and a focusing lens C (11) form focusing light to focus on a sample (15) and a reference reflector (12), the reference reflector (12) is placed at a defocusing position of the front focusing lens C (11) and ensures that the position depth of the reference reflector (12) and the position depth of the upper surface of the sample form a near-distinguishable quasi-common path, and a biaxial displacement platform (15) is adopted for sample movement to realize focusing light scanning, or a biaxial vibrating mirror B (19) is arranged at the input end of the sample arm for scanning the incident light. In a detection light path of the sample arm, a biaxial galvanometer A (13) is adopted to scan and detect a backward scattering field from the sample and the reference reflecting mirror, the effective scanning range of the backward scattering field needs to be consistent with the range of an imaging area of the sample, returned light of the sample arm and the reference arm is interfered in a coupler B (16) and is input to a balance detector (17), a computer synchronously collects interference spectrum data from a Mach-Zehnder interferometer clock box (2) and interference spectrum data from the balance detector (17), and finally a three-dimensional structure of an object at an ultra-deep position in a turbid medium is displayed through data processing.
Fig. 2 is a process flow diagram of an ultra-deep three-dimensional imaging method based on a sweep optical coherence tomography in a turbid medium, and the invention also discloses an ultra-deep three-dimensional imaging method of an ultra-deep three-dimensional imaging device based on the sweep optical coherence tomography in the turbid medium, which comprises the following specific steps:
1. the sample is moved by adopting a biaxial displacement platform or the incident light is scanned by utilizing a biaxial galvanometer B at the input end of a sample arm so as to realize the traversing scanning of the focused light on each position of the sample;
2. at each focusing light scanning position, scanning and detecting and recording interference spectrum signals of the corresponding three-dimensional back scattering field by utilizing a biaxial vibrating mirror A;
3. the device has a measured phase error caused by various interference factors, including wavelength offset between axial scans, mechanical jitter of the biaxial galvanometer A and optical path mismatch, and the phase error can be divided into intra-frame phase fluctuation and inter-frame phase drift according to different change rates: wherein x and y are respectively orthogonal coordinates of the back-scattered field, z is the corresponding depth of the sample signal, According to the different sample scanning modes, when the device adopts a mode of scanning incident light by the biaxial galvanometer B, the incident light can undergo spatially-varying aberration, thereby causing additional intra-frame phase fluctuation, and when the device adopts a displacement platform to move the sample, the incident light is fixed and cannot undergo spatially-varying aberration.
4. Performing inverse Fourier transform on the detected spectrum signals to obtain complex amplitude signals of the three-dimensional back-scattered field from the sample and the reference reflector;
5. In order to compensate the measurement phase error, firstly, according to the clock signal output by the Mach-Zehnder interferometer clock box, calculating the phase error caused by wavelength variation between different axial scanning detection, and compensating the phase error to the corresponding axial scanning signal in the three-dimensional back scattering field:
Where z MZI is the corresponding depth of the clock signal, For the hilbert phase difference between the interference signals generated by the mach-zehnder interferometer clock bins,AndThe phase distribution of the original and first phase compensated sample signal, respectively.
6. Calculating the inter-frame variation of the light field distribution of the reference mirror according to the complex amplitude field of the reference mirror obtained by multiple measurements (corresponding to the scanning of different positions by the focused light), and further compensating to the corresponding three-dimensional back-scattered field, including calculating the inter-frame phase difference of the light field of the reference mirrorThe phase distribution of each frame compensated to the sample signal is aimed at unifying the scanning errors of inconsistent distribution among all fields of the sample signal into one same phase distribution error, and the phase compensation process is described as follows:
Where z R is the depth of the reference mirror signal, E R is normalized by E R＝ER0/|ER0 |, E R0 is the backscattered light field from the reference mirror, Is the phase distribution of the sample signal that is ultimately phase compensated.
7. Fig. 3 is a schematic diagram of the phase compensation result in the present invention, showing the distribution change of the back-scattered field after the above two steps of phase compensation operation, i.e. the intra-frame phase error has been successfully compensated, but the inter-frame phase drift and a specific introduced phase distribution error remain, as shown in fig. 3 b.
8. The phase error remaining after the phase compensation operation is completed is expressed as: Wherein the method comprises the steps of For introducing specific phase distribution errors (abbreviated as),For inter-frame phase drift (dc quantity independent of background distribution), the reflection matrix R e can be expressed as:
Where R is an ideal reflection matrix with no phase error, D is an error matrix composed of phase distribution errors of the reference frame, and E is an error matrix composed of inter-frame phase fluctuations. The process of decomposition of the reflection matrix and reconstruction of the image is as follows:
And Are all time-reversal operators, and the singular value decomposition of matrix R can be expressed asRepresents the conjugate transpose, U and V are unitary matrices, Σ is a diagonal matrix composed of a descending arrangement of singular values (positive real numbers) σ i (i { i e [1, N ] }), and the matrix U d =DU represents that the matrix U is weighted by a phase-only diagonal matrix D, the matrixRepresenting matrix V by a phase-only diagonal matrixWeighting; And Is a two-dimensional wavefront reshaped by the column vector U i、Vi of matrix U, V, and M (M < N) is the optimal number of singular values for reconstruction. Therefore, the background phase change irrelevant to distribution has no influence on image reconstruction, namely the image reconstruction is insensitive to inter-frame phase drift, the uniform phase distribution error has no influence on the image reconstruction, and the post-processing and the image reconstruction of a reflection matrix formed by the compensated complex scattered field are not influenced by the scanning detection of the device.
8. Rearranging two-dimensional fields with the same depth in all the three-dimensional backscattering fields after phase compensation into column vectors, and arranging the column vectors in a reflection matrix according to a scanning track, thereby forming a reflection matrix with a specified depth;
9. The remolding process is carried out on two-dimensional fields with different depths in the three-dimensional back scattering complex field, and a depth-resolved reflection matrix is constructed;
10. filtering most of multiple scattering contributions from the reflection matrix of each depth by adopting a digital pinhole, and then carrying out singular value decomposition and two-dimensional image reconstruction;
11. In the image reconstruction, in order to determine the number of required main singular values, correlation analysis is carried out on image pairs formed by images reconstructed by different numbers of singular values and images reconstructed by corresponding residual singular values, so as to determine the number of optimal main singular values and realize the optimal reconstruction of a two-dimensional image;
12. And arranging the best reconstructed two-dimensional images obtained by each depth according to the depth, so that a successfully recovered three-dimensional target can be obtained, and ultra-deep imaging in the turbid medium can be realized.
FIG. 4 is a graphical representation of the results of the present invention for ultra-deep imaging in a scattering medium, from which it can be seen that conventional SS-OCT methods can reconstruct microspheres only at shallow depths, when the imaging depth is increased (beyond the corresponding depth of microspheres identified as 1), the three-dimensional distribution of microspheres becomes obscured and unrecognizable due to multiple scattering of light within the turbid medium. In contrast, the matrix SS-OCT approach successfully restores the three-dimensional structure distribution of the microspheres and minimizes background noise. The contrast finds that the matrix SS-OCT system expands the imaging depth by three times compared with the traditional SS-OCT system, and realizes the three-dimensional structural reconstruction of the super depth.
The foregoing is merely a preferred embodiment of the present invention, and the present invention has been disclosed in the above description of the preferred embodiment, but is not limited thereto. Any person skilled in the art can make many possible variations and modifications to the technical solution of the present invention or modifications to equivalent embodiments using the methods and technical contents disclosed above, without departing from the scope of the technical solution of the present invention. Therefore, any simple modification, equivalent variation and modification of the above embodiments according to the technical substance of the present invention still fall within the scope of the technical solution of the present invention.

Claims (8)

1.一种浑浊介质中基于扫频光学相干层析技术的超深度三维成像装置，其特征在于，包括依次相连的高速扫频光源、马赫-曾德尔干涉仪时钟箱、耦合器A、包括样品臂和参考臂的干涉仪、耦合器B、平衡探测器和用于处理数据的计算机；所述的参考臂包括准直透镜A和聚焦透镜A；所述的样品臂包括依次相连的准直透镜B、分束镜、聚焦透镜B、样品，以及分束镜一侧依次相连的聚焦透镜C和参考反射镜、另一侧依次相连的双轴振镜A和准直透镜C；所述的样品臂的输入端通过准直透镜B与耦合器A相连，输出端通过准直透镜C与耦合器B相连，所述的样品臂还包括设置于准直透镜B和分束镜之间的双轴振镜B或还包括设置于样品底面，支撑样品的二轴位移平台；1. An ultra-deep three-dimensional imaging device based on swept-frequency optical coherence tomography technology in a turbid medium, characterized in that it comprises a high-speed swept-frequency light source, a Mach-Zehnder interferometer clock box, a coupler A, an interferometer including a sample arm and a reference arm, a coupler B, a balanced detector and a computer for processing data, which are connected in sequence; the reference arm comprises a collimating lens A and a focusing lens A; the sample arm comprises a collimating lens B, a beam splitter, a focusing lens B, a sample, which are connected in sequence, and a focusing lens C and a reference reflector which are connected in sequence on one side of the beam splitter, and a biaxial galvanometer A and a collimating lens C which are connected in sequence on the other side; the input end of the sample arm is connected to the coupler A through the collimating lens B, and the output end is connected to the coupler B through the collimating lens C, and the sample arm also comprises a biaxial galvanometer B arranged between the collimating lens B and the beam splitter, or also comprises a two-axis displacement platform arranged on the bottom surface of the sample to support the sample; 基于浑浊介质中基于扫频光学相干层析技术的超深度三维成像装置用于超深度三维成像方法，包括：The ultra-deep three-dimensional imaging device based on the swept frequency optical coherence tomography technology in turbid media is used for the ultra-deep three-dimensional imaging method, comprising: 采用二轴位移平台移动样品或利用样品臂输入端的双轴振镜B扫描入射光，以实现聚焦光对样品各个位置的遍历扫描；Use a two-axis displacement platform to move the sample or use the two-axis galvanometer B at the input end of the sample arm to scan the incident light, so as to achieve traversal scanning of each position of the sample by the focused light; 在每个聚焦光扫描位置处，利用双轴振镜A扫描探测并记录相应的三维后向散射场的干涉光谱信号；At each focused light scanning position, the interference spectrum signal of the corresponding three-dimensional backscattering field is detected and recorded using a dual-axis galvanometer A scan; 对探测到的光谱信号做逆傅里叶变换，得到来自样品和参考反射镜的三维后向散射场的复振幅信号；Performing inverse Fourier transform on the detected spectral signal to obtain the complex amplitude signal of the three-dimensional backscattered field from the sample and the reference reflector; 根据马赫-曾德尔干涉仪时钟箱输出的时钟信号，计算不同轴向扫描探测之间的由波长变化引起的相位误差，并补偿至三维后向散射场中对应的轴向扫描信号；According to the clock signal output by the clock box of the Mach-Zehnder interferometer, the phase error caused by the wavelength change between different axial scanning detections is calculated and compensated to the corresponding axial scanning signal in the three-dimensional backscattering field; 根据多次测量,即对应聚焦光扫描不同位置时得到的参考反射镜的复振幅场，计算其光场分布的帧间变化，进一步补偿至对应的三维后向散射场；Based on multiple measurements, i.e., the complex amplitude field of the reference reflector obtained when the focused light scans different positions, the inter-frame variation of its light field distribution is calculated, and further compensated to the corresponding three-dimensional backscattering field; 相位补偿操作完成后，仍残留了未补偿的相位，但不影响后续图像重建；After the phase compensation operation is completed, there is still some uncompensated phase left, but it does not affect the subsequent image reconstruction; 将所有相位补偿后的三维后向散射场中同一深度的二维场重排为列向量，按照扫描轨迹将列向量排列在反射矩阵中，由此构成一个指定深度下的反射矩阵；Rearrange the two-dimensional fields at the same depth in all phase-compensated three-dimensional backscattered fields into column vectors, and arrange the column vectors in a reflection matrix according to a scanning trajectory, thereby forming a reflection matrix at a specified depth; 对三维后向散射的复振幅场中不同深度的二维场均进行上一步的重塑过程，构建深度分辨的反射矩阵；The two-dimensional fields at different depths in the three-dimensional backscattered complex amplitude field are reshaped in the previous step to construct a depth-resolved reflection matrix; 对每个深度的反射矩阵采用数字针孔滤除大部分多重散射贡献，然后再进行奇异值分解和二维图像重建；A digital pinhole is used to filter out most of the multi-scattering contribution from the reflectance matrix at each depth, followed by singular value decomposition and 2D image reconstruction; 图像重建中，为确定所需要的主奇异值数量，对不同数量的奇异值重建的图像和相应剩余奇异值重建的图像所构成的图像对进行相关性分析，以确定最佳主奇异值数量，实现二维图像的最佳重建；In image reconstruction, in order to determine the required number of main singular values, correlation analysis is performed on image pairs consisting of images reconstructed with different numbers of singular values and images reconstructed with corresponding remaining singular values to determine the optimal number of main singular values and achieve optimal reconstruction of two-dimensional images; 最后，将每个深度得到的最佳重建的二维图像按深度排列，可得到成功复原的三维目标，实现浑浊介质中的超深度成像。Finally, the best reconstructed two-dimensional images obtained at each depth are arranged according to depth to obtain a successfully restored three-dimensional target, thus achieving ultra-depth imaging in turbid media. 2.根据权利要求1所述的浑浊介质中基于扫频光学相干层析技术的超深度三维成像装置，其特征在于，所述的二轴位移平台用于样品移动实现聚焦光扫描，或将所述的双轴振镜B设置于样品臂的输入端用于扫描入射光。2. According to claim 1, the ultra-deep three-dimensional imaging device based on swept-frequency optical coherence tomography technology in turbid media is characterized in that the two-axis displacement platform is used to move the sample to achieve focused light scanning, or the two-axis galvanometer B is set at the input end of the sample arm to scan the incident light. 3.根据权利要求1或2所述的浑浊介质中基于扫频光学相干层析技术的超深度三维成像装置，其特征在于，所述的参考反射镜放置于其前端聚焦透镜C的离焦位置，且保证参考反射镜的位置深度与样品上表面的位置深度形成相近但可区分的准共路光路。3. The ultra-deep three-dimensional imaging device based on swept-frequency optical coherence tomography technology in turbid media according to claim 1 or 2 is characterized in that the reference reflector is placed at the defocus position of the focusing lens C at its front end, and ensures that the position depth of the reference reflector and the position depth of the upper surface of the sample form a quasi-common path optical path that is similar but distinguishable. 4.根据权利要求3所述的浑浊介质中基于扫频光学相干层析技术的超深度三维成像装置，其特征在于，所述的双轴振镜A，其有效扫描范围需与样品成像区域范围保持一致。4. The ultra-deep three-dimensional imaging device based on swept-frequency optical coherence tomography in turbid media according to claim 3, characterized in that the effective scanning range of the dual-axis galvanometer A must be consistent with the sample imaging area range. 5.根据权利要求1所述的浑浊介质中基于扫频光学相干层析技术的超深度三维成像装置，其特征在于，所述的相位误差，包括：5. The ultra-deep three-dimensional imaging device based on swept frequency optical coherence tomography in turbid media according to claim 1, characterized in that the phase error comprises: 装置存在由多种干扰因素引起的相位误差，包括轴向扫描之间的波长偏移、双轴振镜A的机械抖动以及光路不匹配，按照变化速率的不同，相位误差可分为帧内相位波动和帧间相位漂移：其中，x和y分别为后向散射场的正交坐标，z为样品信号对应深度，为样品扫描位置；The device has phase errors caused by various interference factors, including wavelength offset between axial scans, mechanical jitter of the dual-axis galvanometer A, and optical path mismatch. According to the different rates of change, the phase error can be divided into intra-frame phase fluctuation and inter-frame phase drift: Where x and y are the orthogonal coordinates of the backscattered field, z is the depth corresponding to the sample signal, Scanning location for sample; 根据样品扫描方式的不同，当装置采用双轴振镜B扫描入射光的方式，入射光将经历空间变化的像差，由此造成额外的帧内相位波动；当装置采用位移平台移动样品时，入射光是固定的，不会经历空间变化的像差。Depending on the sample scanning method, when the device uses a dual-axis galvanometer B to scan the incident light, the incident light will experience spatially varying aberrations, thereby causing additional intra-frame phase fluctuations; when the device uses a displacement platform to move the sample, the incident light is fixed and will not experience spatially varying aberrations. 6.根据权利要求1所述的浑浊介质中基于扫频光学相干层析技术的超深度三维成像装置，其特征在于，根据马赫-曾德尔干涉仪时钟箱输出的时钟信号，计算不同轴向扫描探测之间的由波长变化引起的相位误差，并补偿至三维后向散射场中对应的轴向扫描信号，包括：计算马赫-曾德尔干涉仪时钟箱输出的参考信号的希尔伯特变换后的相位差，进行第一步相位补偿操作：6. The ultra-deep three-dimensional imaging device based on swept frequency optical coherence tomography in turbid media according to claim 1, characterized in that, according to the clock signal output by the clock box of the Mach-Zehnder interferometer, the phase error caused by the wavelength change between different axial scanning detections is calculated, and compensated to the corresponding axial scanning signal in the three-dimensional backscattering field, including: calculating the phase difference after Hilbert transformation of the reference signal output by the clock box of the Mach-Zehnder interferometer, and performing the first phase compensation operation: 其中，zMZI是时钟信号对应深度，为马赫-曾德尔干涉仪时钟箱生成的干涉信号之间的希尔伯特相位差，和分别是原始的和第一次相位补偿后的样品信号的相位分布。Among them, z MZI is the depth corresponding to the clock signal, is the Hilbert phase difference between the interferometric signals generated by the Mach-Zehnder interferometer clock boxes, and They are the phase distribution of the original sample signal and the phase distribution after the first phase compensation. 7.根据权利要求1或5或6所述的浑浊介质中基于扫频光学相干层析技术的超深度三维成像装置，其特征在于，所述的根据多次测量得到的参考反射镜的复振幅场，计算其光场分布的帧间变化，进一步补偿至对应的三维后向散射场，包括：7. The ultra-deep three-dimensional imaging device based on swept frequency optical coherence tomography in turbid media according to claim 1, 5 or 6, characterized in that the inter-frame variation of the light field distribution is calculated based on the complex amplitude field of the reference reflector obtained by multiple measurements, and further compensated to the corresponding three-dimensional backscattering field, comprising: 计算参考反射镜的光场的帧间相位差补偿至样品信号的每一帧相位分布，其目的是将样品信号所有场之间分布不一致的扫描误差统一为一个相同的相位分布误差，相位补偿过程描述为：Calculate the inter-frame phase difference of the light field of the reference mirror The purpose of compensating the phase distribution of each frame of the sample signal is to unify the inconsistent scanning errors between all fields of the sample signal into the same phase distribution error. The phase compensation process is described as: 其中，zR是参考镜信号对应深度，ER由ER＝ER0/|ER0|归一化得到，ER0是来自参考反射镜的后向散射光场，是最终完成相位补偿的样品信号的相位分布。Where z R is the depth corresponding to the reference mirror signal, ER is normalized by ER = ER0 /| ER0 |, ER0 is the backscattered light field from the reference reflector, It is the phase distribution of the sample signal after phase compensation is finally completed. 8.根据权利要求7所述的浑浊介质中基于扫频光学相干层析技术的超深度三维成像装置，其特征在于，所述的相位补偿操作完成后，仍残留了未补偿的相位，但不影响后续图像重建，包括：8. The ultra-deep three-dimensional imaging device based on swept frequency optical coherence tomography in turbid media according to claim 7, characterized in that after the phase compensation operation is completed, an uncompensated phase still remains, but does not affect subsequent image reconstruction, comprising: 将残留的相位误差表示为：其中为引入的特定的相位分布误差，简化为为帧间相位漂移，是与背景分布无关的直流量；此时，反射矩阵Re可以表示为：The residual phase error is expressed as: in The specific phase distribution error introduced is simplified to is the inter-frame phase drift, which is a DC quantity independent of the background distribution. At this time, the reflection matrix Re can be expressed as: 其中R是无相位误差存在的理想反射矩阵，D是由参考帧的相位分布误差构成的误差矩阵，E是帧间相位波动构成的误差矩阵；反射矩阵的分解与图像的重建过程如下：Where R is the ideal reflection matrix without phase error, D is the error matrix composed of the phase distribution error of the reference frame, and E is the error matrix composed of the phase fluctuation between frames; the decomposition of the reflection matrix and the reconstruction process of the image are as follows: 和都是时间反转算子；矩阵R的奇异值分解可以表示为表示共轭转置；U和V是酉矩阵；Σ是对角矩阵，由正实数奇异值σi降序排列构成，其中 and are all time reversal operators; the singular value decomposition of the matrix R can be expressed as represents conjugate transpose; U and V are unitary matrices; Σ is a diagonal matrix consisting of positive real singular values σ i arranged in descending order, where i∈[1,N]；矩阵Ud＝DU表示矩阵U由一个仅相位的对角矩阵D加权，矩阵表示矩阵V由一个仅相位的对角矩阵加权；和是由矩阵U、V的列向量Ui、Vi重塑的二维波前；M是用于重建的奇异值的最优化数量，其中，M<N。i∈[1,N]; the matrix U d = DU means that the matrix U is weighted by a phase-only diagonal matrix D. Represents the matrix V as a phase-only diagonal matrix Weighting; and is the two-dimensional wavefront reshaped by the column vectors U i , V i of the matrices U, V; M is the optimal number of singular values used for reconstruction, where M<N.
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