CN112704470A - Spectrum-splitting frequency domain coherence tomography system - Google Patents

Abstract

Translated fromChinese

本发明公开了一种分光谱频域相干断层成像系统，利用可调滤波器将宽光谱光源输出的光波滤波为若干个带宽较窄的分光谱，分别依次输入一个基于频域光学相干断层成像系统的干涉仪，并依次检测对应的分光谱干涉信号；通过数据后处理，将分光谱干涉信号相位对齐集成为一个合成干涉信号，傅里叶变换得到物体不同深度解析的更高分辨率、更高信噪比的样本断层图像。由于分光谱输出以较低的光强照射样本，该成像系统可以避免样本损伤或对样本造成不适，同时能够通过后续数据处理将若干个较低光强原始信号合成为一个高信噪比的图像，从而提升谱域光学相干断层成像的性能，易于临床转化和应用。

The invention discloses a subspectral frequency domain coherence tomography imaging system, which uses an adjustable filter to filter light waves output from a wide-spectrum light source into several subspectral spectra with narrower bandwidths, which are respectively input into an optical coherence tomography imaging system based on frequency domain. The interferometer is used to detect the corresponding spectral interference signals in turn; through data post-processing, the spectral interference signals are phase-aligned and integrated into a composite interference signal, and the Fourier transform can obtain higher resolution and higher resolution at different depths of the object. A sample tomogram of the signal-to-noise ratio. Since the sub-spectral output illuminates the sample with a lower light intensity, the imaging system can avoid damage to the sample or cause discomfort to the sample, and at the same time, it can combine several original signals of lower light intensity into a high signal-to-noise ratio image through subsequent data processing. , thereby improving the performance of spectral domain optical coherence tomography, which is easy for clinical translation and application.

Description

Spectrum-splitting frequency domain coherence tomography system

Technical Field

The invention relates to the field of optical imaging, in particular to a spectral frequency domain coherence tomography system.

Background

Optical Coherence Tomography (OCT) is a tomographic imaging technique based on the principle of light interference, and uses the interference of a reference arm light and a sample arm light to detect reflected or scattered signals of light at different depths of a sample, thereby obtaining the tomographic structure information of the sample. OCT has been widely used in the field of ophthalmology and cardiovascular diagnosis in clinical practice, and has become the gold standard for diagnosis of ophthalmic diseases in particular. The currently mainstream OCT system is based on the Fourier Domain OCT (FDOCT) imaging principle. FDOCT is mainly classified into two types, one is spectral-Domain OCT (SDOCT), i.e., spectral-Domain OCT, in which the intensity of interference signals of different wavelengths or wave numbers is detected by a spectrometer at a detection end, and a sample tomographic image is further obtained by fourier transform. The other technique is Swept-Source OCT (SS OCT), which uses a fast Swept-Source to transform the input wavelength, thereby detecting the intensity of interference signals of different wavelengths or wave numbers, and further obtains a sample tomographic image through fourier transform. The SDOCT and the SSOCT are two different implementation forms of the FDOCT, the principle based on which is similar in nature is used for equivalently acquiring information of different depths of a sample by detecting interference signals with different wavelengths or wave numbers, and the mechanical position movement of a reference arm of a time domain OCT system is avoided, so that the imaging speed and the signal-to-noise ratio of an image are remarkably improved. The invention belongs to a new technology of SDOCT branching.

OCT is used for biomedical tissue imaging. Generally, in order to avoid damage to the imaged biomedical tissue, the OCT incident light intensity is controlled within a certain safety threshold. The light intensity safety threshold for maximum light incidence in OCT varies from application to application and from type to type of biological tissue being illuminated. In general, it is desirable to increase the incident light intensity as much as possible within a safe threshold because the signal-to-noise ratio of the image is directly and positively correlated with the incident light intensity. However, for certain clinical-specific applications, such as ophthalmic imaging, too strong incident light is likely to cause discomfort to the patient's eye. Although ophthalmic OCT generally employs near-infrared bands, such as those around 830nm or 1064nm, the patient's eye is not sensitive to near-infrared light intensity; however, in recent years OCT with rapid development [ Xiao Shu et al, 'design visual-light optical coherence tomography attacks themselves ics cl ics', Quant Imaging Med Surg 2019; 769 (5) 769-781) the imaging technique uses the visible light band between 450-700nm, which causes discomfort to the eyes of the patient during imaging. Because OCT imaging needs eyes to keep still, and focus positioning is carried out by watching a certain target; the use of more sensitive visible light imaging makes it difficult for the patient to keep the eye still and in focus during imaging, which may be accompanied by eye movement, significantly affecting the imaging quality. It is therefore desirable that the incident light intensity is not too high in terms of patient comfort and avoidance of imaging artifacts, but this is in contrast to the clinical need to improve the image signal-to-noise ratio and image quality to obtain high-resolution images for disease diagnosis. The visible light OCT has a shorter wavelength, has a higher resolution than the current mainstream near-infrared light OCT, and can acquire blood flow and blood oxygen information required for diagnosing a number of major diseases while performing structural imaging because blood in a living body is more sensitive to absorption of visible light, so that the visible light OCT is a new imaging technology which is emerging at present and is generally seen in the field. However, the clinical transformation and application of visible light OCT is limited due to the inherent contradiction between the discomfort of imaging the diseased eye and the improvement of the image signal-to-noise ratio. Therefore, there is a need for a new technique that can make the OCT system obtain a high snr image with a low incident light intensity, not only can make the visible light OCT technique practical and further implement clinical transformation, but also can be used in any existing SDOCT system to enhance the snr and image quality of the image.

Disclosure of Invention

The invention aims to provide a spectral frequency domain coherence tomography system which can irradiate a sample with lower light intensity, avoid sample damage or discomfort to the sample, and simultaneously can synthesize a plurality of lower light intensity original signals into an image with high signal to noise ratio through subsequent data processing, thereby improving the performance and the practicability of spectral domain OCT (optical coherence tomography), particularly visible light OCT, and facilitating clinical transformation and application of related technologies.

In order to achieve the purpose, the invention discloses a spectral frequency domain coherence tomography system, which is characterized in that a wide spectrum light source used by OCT is externally connected with a wavelength tunable filter, light waves output by the wide spectrum light source are filtered into a plurality of spectral spectrums with narrower bandwidths, the spectral spectrums are respectively and sequentially input into an interferometer of the OCT system, and corresponding spectral spectrum interference signals are detected; and aligning the phases of the spectral interference signals through data post-processing, splicing the spectral interference signals into a synthesized interference signal, and finally obtaining the OCT image with higher resolution and higher signal-to-noise ratio for analyzing different depths of the object through Fourier transform.

The invention provides a spectral frequency domain coherence tomography system which mainly comprises a broad spectrum light source, an adjustable filter, a beam splitter, a plurality of polarization regulators for optical fiber polarization regulation, a plurality of lenses for focusing and collimation, a reference arm plane mirror, a sample arm scanning lens, a grating of a spectrometer part, a line scanning camera and other core elements. The imaging principle of the spectral frequency domain coherence tomography system is that light waves generated by a broad spectrum light source are output from an adjustable filter, and after the light waves are split by a light splitter, one path of light is led to a reference arm and is reflected by a plane mirror of the reference arm; the other light is directed to the sample arm, and the sample is illuminated by a scanning device, such as a scanning galvanometer or a motor, and the light reflected or scattered back from the sample interferes with the light wave reflected from the reference arm. The interference light wave is divided into components with different wavelengths through the grating, and after being focused by the lens, the components of the interference signals with different wavelengths are detected by the line scanning camera. When the tunable filter changes the output wavelength range, interference signals of different wavelength components passing through the grating are focused on pixels at different positions of the line scanning camera. Therefore, by sequentially changing the output of the tunable filter, interference signals in different wavelength ranges corresponding to different spectral spectrums, i.e., spectral spectrum interference signals, can be sequentially detected. And further carrying out data post-processing to match the phases of the interference signals in different wavelength ranges, and further splicing the interference signals into a synthesized interference signal to finally obtain a synthesized image. Compared with an image obtained by single spectral imaging, the synthetic image has higher resolution and higher signal-to-noise ratio.

An important component of the spectral frequency domain coherence tomography system is to splice spectral interference signals detected by a line scanning camera, i.e. interference signals of different wavelength ranges corresponding to different spectral spectrums, through frequency axes, after phase alignment, the synthesized interference signals are obtained by splicing. And further carrying out Fourier transform on the synthesized interference signal to obtain a synthesized high-resolution and high-signal-to-noise-ratio image. Preferably, an implementation method for phase-aligning and splicing the spectral interference signals into the synthetic interference signal can be implemented by the following steps: first, a single reflective element, such as a transparent glass plate, is placed outside the imaging range of the sample (e.g., sample depth position of 0-1mm, >1mm outside the sample imaging range), as allowed by the OCT system. Because the interference signals obtained by the OCT system contain the interference signals of samples with different depths (including the added single reflection element based on the frequency domain OCT imaging principle), the interference signals corresponding to the single reflection element can be separated by a time domain filtering or Fourier domain filtering method. And further carrying out Fourier transform on interference signals corresponding to the separated single reflection elements to obtain phases of different spectral interference signals, comparing and registering the phases, matching the phase of one spectral interference signal with the phase of the other spectral interference signal, and splicing the spectral interference signals into a synthesized interference signal. For other spectral interference signals, the synthesis can be performed step by step in the above manner.

According to the invention, by means of a spectrum spectral frequency domain coherence tomography technology, a spectrum interference signal obtained by irradiating a sample with a spectrum with lower light intensity is spliced through a frequency axis in a data post-processing process, and after phases are aligned, a synthesized interference signal is obtained by splicing; and further, a high-resolution and high-signal-to-noise-ratio synthetic image is obtained through Fourier transform, a practical method which is more friendly to sample imaging and can simultaneously obtain a high-signal-to-noise-ratio image is provided for the clinical application sensitive to light intensity, and the large-scale clinical application of spectral domain OCT (optical coherence tomography), particularly visible light OCT technology, is facilitated. The technology provided by the invention can also be used for splicing interference signals obtained by sequentially irradiating a sample by a plurality of independent spectral light sources, and a synthetic interference signal is obtained by splicing through frequency axis splicing and phase matching in the data post-processing process; further obtaining a synthetic image through Fourier transform; the resolution and signal-to-noise ratio of the composite image are significantly enhanced over images obtained from a single light source.

Drawings

FIG. 1 is a schematic diagram of a spectral spectrum frequency domain coherence tomography system provided by the present invention

FIG. 2 is a diagram of a conventional frequency-domain OCT system

FIG. 3 is a schematic diagram of the output of the spectrum of a broad spectrum light source through a tunable filter as a series of sub-spectral outputs

FIG. 4 is a method for splicing spectral interference signals into synthesized interference signals and obtaining a synthesized image

FIG. 5 is a method for splicing synthetic interference signals based on phase matching of interference signals corresponding to a single reflective element

FIG. 6 is a method for extracting and separating interference signals corresponding to single reflection elements from interference signals based on time-domain filtering

FIG. 7 is a Fourier domain filtering-based method for extracting and separating interference signals corresponding to single reflection elements from the interference signals

FIG. 8 is a schematic diagram of splicing a spectroscopic interference signal into a composite interference signal

FIG. 9 shows that the light intensity of the sample irradiated by the spectral output light wave is much less than the light intensity of the sample irradiated by the original broad spectrum light source

FIG. 10 is a spectral band coherence tomography system integrating multiple light sources of different wavelengths

Detailed Description

The technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

As shown in fig. 1, a spectral-domaincoherence tomography system 50 provided by the present invention mainly includes a broadspectrum light source 1, anadjustable filter 21, abeam splitter 3, a polarization adjuster 4, alens 5, a referencearm plane mirror 6, a samplearm scanning galvanometer 9, agrating 7 of a spectrometer part, aline scanning camera 8, and other core elements. The imaging principle of the spectral frequency domain coherence tomography system is that after light waves generated by a broadspectrum light source 1 are output from anadjustable filter 21 and split by a light splitter, one path of light is led to a reference arm and is reflected by a referencearm plane mirror 6 after being collimated by alens 5; the other path of light is led to a sample arm and irradiates a sample through ascanning galvanometer 9, such as different positions of human eyes; light reflected or scattered back from the sample interferes with the light waves reflected from the reference arm. The polarization adjuster 4 in fig. 1 is used to adjust the polarization state of the light waves of the reference arm and the sample arm. The interference light waves are divided into different wavelength components by the grating, focused by the lens and detected by theline scanning camera 8. That is, the interference signal detected by theline scanning camera 8 is a component of the interference signal of different wavelengths. When thetunable filter 21 changes the output wavelength range, interference signals of different wavelength components passing through the grating are focused on pixels at different positions of the line scan camera. Therefore, by sequentially changing the output of thetunable filter 21, the interference signals 31 in different wavelength ranges corresponding to different spectral components, i.e., thespectral interference signals 31, can be sequentially detected. Further, through data post-processing, theinterference signals 31 in different wavelength ranges are sequentially subjected tofrequency axis splicing 32 andphase alignment 33, and further spliced into acomposite interference signal 34, and thecomposite interference signal 34 is sequentially subjected to spectrum shaping 35 and Fouriertransform 42, so that acomposite image 36 is finally obtained. Thecomposite image 36 has a higher resolution and a higher signal-to-noise ratio than images obtained by single spectral imaging.

As shown in fig. 1, a key component of the spectral frequency domaincoherence tomography system 50 is thetunable filter 21. Preferably, the output wavelength (or frequency) of thetunable filter 21 can be dynamically adjusted in real time by using a control software running on a computer, and using USB or internet or bluetooth or other communication control methods. In the spectral-domain coherence tomography system, thetunable filter 21 filters the light waves output from the broad-spectrum light source 1 into a plurality ofspectral spectrums 22 with narrower bandwidths.

Preferably, to facilitate phase alignment of the spectral interference signals and further stitching into a composite interference signal, a single semi-transparentreflective element 15, such as a transparent glass plate, is placed outside the imaging distance of the sample 10 (e.g., sample depth position of 0-1mm, >1mm outside the sample imaging distance), within the allowed imaging range of the OCT system. In subsequent signal processing, extracting an interference signal corresponding to the single reflection element assists in phase alignment and splicing of spectral interference signals, and further details can be found in fig. 5 and related description.

Fig. 2 is a schematic diagram of a conventional frequency domain oct (sdoct) system. It can be seen that, compared with the spectral spectrum domain coherence fault system provided by the present invention, the conventional SDOCT does not have thetunable filter 21 to regulate the output wavelength of the light source, and emits light of all wavelengths at the same time; the spectral spectrum domain coherence tomography system only outputs light with a part of wavelengths through thetunable filter 21 at a time, and outputs light waves with different wave bands through rapidly adjusting the output wavelengths of thetunable filter 21. In addition, the conventional SD OCT simultaneously detects interference signals of all wavelengths by theline scanning camera 8 using a spectrometer, and the spectral spectrum coherence fault system sequentially detects interference signals 23 (or 31) of wavelengths corresponding to different spectral spectrums in sequence, and interference signals obtained by each spectral spectrum correspond to different pixel positions of the line scanning camera.

As shown in fig. 3, thetunable filter 21 adjusts the wavelength band of the broad spectrum light source through the frequency band of the filter, and outputs a series of spectral outputs in different wavelength band ranges. Assuming a wide-spectrum light source output wavelength range of lambda_s1And λ_s2Or corresponding to wave number k_s1And k_s2Wherein k is 2 pi/λ. Preferably, for OCT imaging, the light source bandwidth is at least 30nm, i.e. λ is satisfied_s2-λ_s1≥30n m. The output of the adjustable filter is n sub-spectrums with narrower bandwidth, wherein n is an integer within 1-10000; let the ith spectral wavelength range be λ_i1And λ_i2Wherein i is more than or equal to 1 and less than or equal to n, the output wavelength of the spectrum needs to satisfy the following conditions: lambda [ alpha ]_s1≤λ_i1≤λ_i2≤λ_s2(ii) a And for all 1 ≦ i<j is less than or equal to n, has lambda_i1<λ_j1，λ_i2<λ_j2. Preferably, λ_s1The value range can be 380nm-1350nm, lambda_s2The value range can be 410nm-1380 nm. According to the above definition, there may be a coincidence of the wavelength ranges between two successive sub-spectra, i.e. satisfying λ_i1≤λ_(i+1)1≤λ_i2≤λ_(i+1)2I is less than or equal to n-1 for all 1, and the bandwidths of the sub-spectra are not necessarily equal.

For an OCT system, its axial resolution can be described by the following equation:

where Δ λ is the light source bandwidth. That is, the wider the bandwidth of the light source, the smaller the scale that the OCT system can resolve, i.e., the higher the axial resolution. The bandwidth of thelight wave 22 output by thetunable filter 21 is narrower than that of the output (2) of the original broad-spectrum light source, but after the light wave is spliced into a synthesized interference signal through a subsequent frequency axis, the bandwidth of the original broad-spectrum light source can be restored, so that higher axial resolution is obtained.

Fig. 4 is a method of stitching the spectral interference signals 31 into acomposite interference signal 34 and ultimately resulting in acomposite image 36. As mentioned above, since there may be overlap of wavelength ranges between the spectra, wavelength and frequency bands not containing repeated bands can be spliced together by thefrequency axis splicing 32. Because interference signals of different spectral spectrums are subjected to grating light splitting and lens focusing and then are detected by pixels at different positions of a line scanning camera, the corresponding wavelength of each spectral spectrum interference signal can be identified according to the coordinate position of the detected signal, signals with repeated wavelengths are removed, and non-repeated but continuous wavelength axes are spliced together. On this basis, the wavelength-segmented interference signals are phase-aligned 33 and spliced into acomposite interference signal 34. Finally, the synthesized interference signal is subjected to spectral waveform shaping 35, and afourier transform 42 is performed to obtain asynthesized image 36. Preferably, one method of spectral shaping is to shape the interference signal of an arbitrary envelope into an interference signal having a gaussian-like envelope by multiplying by a window function. Common window functions include Hamming window function, Hanning window function, gaussian window function, etc.

Fig. 5 is a method for extracting an interference signal corresponding to a single reflection element in two spectral interference signals 31, that is, extracting a single-plane interference signal 41 to obtain spectral single-plane interference signals, then obtaining phases of the two spectral single-plane interference signals through fourier transform 42, performing phase comparison and matching 43, performing linearwave number interpolation 44, fourier transform 42,phase delay compensation 45 and inverse fourier transform 46 on one of the original spectral interference signals 31 by using comparison information, and further splicing the original spectral interference signals with the other originalspectral interference signal 31 to form a synthesizedinterference signal 34. As mentioned above, the extraction of the interference signal corresponding to the single reflective element can be achieved by adding a transparent glass plate or similar sample outside the imaging range of the sample, or within the imaging range of OCT. If the sample has a single plane reflecting surface, the single plane reflecting surface can be directly used for extracting phase information.

Fig. 6 is a method for extracting a spectroscopic single-plane interference signal from thespectroscopic interference signal 31 by using a time-domain filtering 47 method. Since the single plane reflects a signal corresponding to one depth, that is, a frequency component in the fourier domain OCT, the signal of the reflecting surface can be effectively extracted by setting a band-pass filter of an appropriate frequency. Because the signal collected by the line scanning camera is an interference signal with uniformly distributed wavelengths obtained by gratingdispersion 7, the signal is resampled byinterpolation 44 from linear wavelengths to linear wave number frequency axes in the post-processing process, so as to obtain a single-plane interference signal of a spectrum corresponding to the frequency axes uniformly distributed by wave numbers.

Fig. 7 is a method of extracting a spectroscopic monoplane interference signal from thespectroscopic interference signal 31 usingfourier filtering 49. At this time,resampling interpolation 44 of linear wavelength to linear wavenumber frequency axis is firstly performed on thespectral interference signal 31, then the signal is transformed to fourier domain by fourier domain filtering, the frequency of the interference signal corresponding to the single reflection element is retained, other frequency bands are filtered, and then the filtered spectral single-plane interference signal is obtained by fourier inverse transformation.

Fig. 8 shows a schematic diagram of thespectroscopic interference signal 31 and the resultingcomposite interference signal 34. It can be seen that the frequency of the interference signal is lower due to the narrower bandwidth of the sub-spectral band. By phase alignment, the interference signal obtained after splicing is similar to that obtained by directly imaging with an original broad-spectrum light source. The difference is that the optical fiber is spliced by a series of spectral interference signals with lower incident energy, and the sample sensitive to light intensity is more friendly when being imaged.

Fig. 9 compares the light intensity comparison graphs of the spectral incident sample and the original wide-spectrum light source full-spectrum incident sample (the spectrallight intensity 56 compares the full-spectrum light intensity 57. obviously, the incident light intensity can be obviously reduced by using the spectral light waves and inputting the samples in sequence, and for the application represented by visible light OCT, the discomfort of the patient in the imaging process is reduced, the rapid eye movement in the imaging process is avoided, the imaging quality is improved.

As shown in fig. 10, another implementation method of the spectral coherence tomography system proposed by the present invention is to input nlight sources 61 with narrow bandwidth into the SDOCT system interferometer through theoptical switch 63, wherein n is an integer within 1-10000. By means of the spectrometer, interference signals 31 of different wavelength ranges corresponding to different light sources are sequentially detected. Further, through data post-processing, the interference signals 31 in different wavelength ranges are phase-matched and further spliced into acomposite interference signal 34, and finally acomposite image 36 is obtained. Thecomposite image 36 has a higher resolution and a higher signal-to-noise ratio than images obtained by imaging with a single light source.

In the system shown in FIG. 10, which includes n narrow-bandwidth light sources as inputs, assume that the ith lightsource output wavelength 62 ranges from λ_i1And λ_i2Wherein i is more than or equal to 1 and less than or equal to n and lambda_i1≤λ_i2. Preferably, λ_i1The value range can be 380nm-1380nm, lambda_i2The value range can be 380nm-1380 nm. According to the above definition, there may be a coincidence of wavelength ranges between different light sources, and the bandwidths of the outputs of the light sources are not necessarily equal. The interference signals obtained by the incidence of each light source are respectively used for finding out the corresponding wavelength or frequency range through the pixel position detected on the line scanning camera, after the size sorting, the repeated wavelength or frequency components are removed, and after the phase positions are aligned, the synthesized interference signals are obtained by splicing.

The embodiments described above are only a part of the embodiments of the present invention, and not all of them. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Claims (10)

Translated fromChinese

1.一种分光谱频域相干断层成像系统，其特征在于，该分光谱频域相干断层成像系统(50)利用可调滤波器(21)将宽光谱光源(1)输出的光波滤波为若干个光强较宽光谱光源(1)输出的光波光强弱、带宽较宽光谱光源(1)输出的光波带宽窄的分光谱(22)，将分光谱(22)分别依次输入一个基于频域光学相干断层成像(SDOCT)系统的干涉仪，并依次检测对应的分光谱干涉信号(23或31)；通过数据后处理，将分光谱干涉信号(23或31)相位对齐拼接为一个合成干涉信号(34)，最后通过傅里叶变换得到物体不同深度解析的高分辨率高信噪比的SDOCT图像；1. A spectral frequency domain coherence tomography imaging system, characterized in that the spectral spectral frequency domain coherence tomography imaging system (50) utilizes a tunable filter (21) to filter the light waves output by the wide-spectrum light source (1) into several A sub-spectrum (22) with a narrow light wave bandwidth output by the light source (1) with a relatively wide light intensity and a relatively wide bandwidth of the light wave output by the light source (1), and the sub-spectra (22) are respectively input into a frequency domain-based The interferometer of the optical coherence tomography (SDOCT) system detects the corresponding spectral interference signals (23 or 31) in sequence; through data post-processing, the spectral interference signals (23 or 31) are phase-aligned and spliced into a composite interference signal (34), and finally obtain high-resolution and high-signal-to-noise ratio SDOCT images of different depths of the object through Fourier transform;其中，可调滤波器(21)通过程序控制输出中心波长和带宽范围，并可在成像过程中快速调整可调滤波器的输出范围；SDOCT系统的干涉仪部分与当前成熟的SDOCT系统类似，包含分光器(3)，偏振调节器(4)，透镜(5)，参考臂平面镜(6)，样本臂扫描振镜(9)，光谱仪部分的光栅(7)，线扫描相机(8)这一系列核心元件，偏振调节器(4)用于调节参考臂和样本臂光波的偏振态；所述分光谱频域相干断层成像系统的成像原理是，从宽光谱光源输出的光波经过可调滤波器输出后，经过分光器分光，一路光通向参考臂，被平面镜(6)反射；另一路光通向样本臂，通过样本臂扫描振镜(9)或其他扫描装置照射样本(10)，从样本(10)反射或散射回来的光与从参考臂反射的光波发生干涉；干涉光波通过光栅分为不同波长分量，经过透镜聚焦后，被线扫描相机(8)检测，也就是说，线扫描相机(8)检测到的干涉信号是不同波长的干涉信号的分量；当可调滤波器(21)改变输出波长范围时，经过光栅的不同波长分量的干涉信号会被透镜聚焦于线扫描相机(8)不同位置的像素上，因此通过依次改变可调滤波器(21)的输出，线扫描相机(8)顺序检测到不同分光谱所对应的不同波长范围的干涉信号(31)，即分光谱干涉信号(31)；进一步通过数据后处理，将不同波长范围的干涉信号(31)依次进行频率轴拼接(32)和相位对齐(33)，进一步拼接为一个合成干涉信号(34)，该合成干涉信号(34)依次经过光谱整形(35)和傅里叶变换(42)，最终得到合成的图像(36)，该合成的图像(36)相比单独分光谱成像得到的图像分辨率更高，信噪比也更高；Among them, the tunable filter (21) can control the output center wavelength and bandwidth range through the program, and can quickly adjust the output range of the tunable filter during the imaging process; the interferometer part of the SDOCT system is similar to the current mature SDOCT system, including Beam splitter (3), polarization adjuster (4), lens (5), reference arm plane mirror (6), sample arm scanning galvanometer (9), grating of spectrometer section (7), line scan camera (8) this A series of core components, the polarization adjuster (4) is used to adjust the polarization state of the light waves of the reference arm and the sample arm; the imaging principle of the spectral sub-frequency domain coherence tomography imaging system is that the light waves output from the wide-spectrum light source pass through a tunable filter After the output, the light is split by the spectroscope, and one path of light leads to the reference arm and is reflected by the plane mirror (6); the other path of light leads to the sample arm, and the sample (10) is irradiated by the sample arm scanning galvanometer (9) or other scanning device, and the The light reflected or scattered back by the sample (10) interferes with the light wave reflected from the reference arm; the interfering light wave is divided into different wavelength components by the grating, and after being focused by the lens, is detected by the line scan camera (8), that is, the line scan The interference signals detected by the camera (8) are components of interference signals of different wavelengths; when the tunable filter (21) changes the output wavelength range, the interference signals of different wavelength components passing through the grating will be focused by the lens on the line scan camera ( 8) On pixels at different positions, therefore by sequentially changing the output of the tunable filter (21), the line scan camera (8) sequentially detects interference signals (31) in different wavelength ranges corresponding to different sub-spectra, that is, the sub-spectrum interference signal (31); further through data post-processing, the interference signals (31) in different wavelength ranges are sequentially spliced in frequency axis (32) and phase aligned (33), and further spliced into a composite interference signal (34). The interference signal (34) undergoes spectral shaping (35) and Fourier transform (42) in sequence, and finally a composite image (36) is obtained, which has a higher resolution than the image obtained by separate spectral imaging , the signal-to-noise ratio is also higher;该分光谱频域相干断层成像系统(50)利用可调滤波器(21)将宽光谱光源(1)输出的光波滤波为若干个较窄的分光谱(22)，每个分光谱对应的光强小于原始宽光谱光源所对应的光强，从而避免对光强敏感的样本造成损伤；The subspectral frequency-domain coherence tomography imaging system (50) uses a tunable filter (21) to filter the light wave output from the wide-spectrum light source (1) into several narrower sub-spectra (22), and the light corresponding to each sub-spectrum The intensity is lower than the light intensity corresponding to the original broad-spectrum light source, so as to avoid damage to samples sensitive to light intensity;所述可调滤波器(21)的输出波长通过运行在计算机上的控制软件，采用USB或网线或蓝牙或其他通讯控制方式进行动态实时调整。The output wavelength of the tunable filter (21) is dynamically adjusted in real time through the control software running on the computer, using USB or network cable or Bluetooth or other communication control methods.2.根据权利要求1所述的分光谱频域相干断层成像系统，其特征在于，分光谱频域相干断层成像系统(50)利用可调滤波器(21)将宽光谱光源(1)输出的光波滤波为若干个光强较宽光谱光源(1)输出的光波光强弱，带宽较宽光谱光源(1)输出的光波带宽窄的分光谱(22)；宽光谱光源(1)输出波长范围为λ_s1和λ_s2，光源带宽至少为30nm，即满足λ_s2-λ_s1≥30nm；可调滤波器(21)输出为n个带宽较窄的分光谱，其中n是1-10000之内的整数；假设第i个分光谱波长范围为λ_i1和λ_i2,其中1≤i≤n，那么分光谱输出波长满足以下条件：λ_s1≤λ_i1≤λ_i2≤λ_s2；且对于所有1≤i<j≤n，有λ_i1<λ_j1，λ_i2<λ_j2；连续两个分光谱之间可能有波长范围的重合，即满足λ_i1≤λ_(i+1)1≤λ_i2≤λ_(i+1)2对于所有1≤i≤n-1，且各分光谱的带宽不一定相等。2. The spectral frequency domain coherence tomography system according to claim 1, wherein the spectral spectral frequency domain coherence tomography system (50) utilizes a tunable filter (21) to output the wide-spectrum light source (1). The light wave filtering is divided into a sub-spectrum (22) with a narrow bandwidth of light waves output by a plurality of light-intensity wide-spectrum light sources (1) with weak light intensity and a wide-bandwidth spectral light source (1). are λ_s1 and λ_s2 , the light source bandwidth is at least 30 nm, that is, λ_s2 -λ_s1 ≥30 nm; the output of the tunable filter (21) is n sub-spectra with narrow bandwidth, where n is within 1-10000 Integer; assuming that the i-th sub-spectral wavelength range is λ_i1 and λ_i2 , where 1≤i≤n, then the sub-spectral output wavelength satisfies the following conditions: λ_s1 ≤λ_i1 ≤λ_i2 ≤λ_s2 ; and for all 1≤ i<j≤n, λ_i1 <λ_j1 , λ_i2 <λ_j2 ; there may be overlapping wavelength ranges between two consecutive sub-spectra, that is, λ_i1 ≤λ_(i+1)1 ≤λ_i2 ≤λ_(i+1)2 for all 1≤i≤n-1, and the bandwidth of each sub-spectrum is not necessarily equal.3.根据权利要求2所述的分光谱频域相干断层成像系统，所述宽光谱光源(1)输出波长范围λ_s1和λ_s2，以及可调滤波器(21)输出分光谱波长范围λ_i1和λ_i2，其中1≤i≤n且为整数，λ_s1取值范围可为380nm-1350nm，λ_s2取值范围可为410nm-1380nm。3. The spectral frequency domain coherence tomography system according to claim 2, wherein the wide-spectrum light source (1) outputs wavelength ranges λ_s1 and λ_s2 , and a tunable filter (21) outputs a spectral wavelength range λ_i1 and λ_i2 , where 1≤i≤n and an integer, the value range of λ_s1 may be 380nm-1350nm, and the value range of λ_s2 may be 410nm-1380nm.4.根据权利要求3所述的分光谱频域相干断层成像系统，其特征在于，将不同分光谱所对应的不同波长范围的干涉信号(31)拼接为合成干涉信号(34)并最终得到合成的图像(36)的一种方法可通过如下步骤实现：由于各分光谱之间波长范围可能有重合，可通过频率轴拼接(32)的方法将不包含重复段的波长频率段拼接起来，由于不同分光谱干涉信号经过光栅分光、透镜聚焦后被线扫描相机的不同位置的像素检测，因此根据所检测信号的坐标位置识别各分光谱干涉信号所对应的波长，将波长重复的信号去掉，并将波长非重复但连续的频率轴拼接起来；在此基础上，对各波长分段干涉信号进行相位对齐(33)，拼接为合成的干涉信号(34)；最后，对合成的干涉信号(34)进行光谱整形(35)，通过傅里叶变换(42)得到合成后的图像(36)，光谱整形的方法是将任意包络的干涉信号通过乘以一个窗函数整形为具有类似高斯包络的干涉信号，所述窗函数包括Hamming窗函数，Hanning窗函数，高斯窗函数等。4. The spectral frequency domain coherence tomography system according to claim 3, wherein the interference signals (31) of different wavelength ranges corresponding to different spectral spectra are spliced into a composite interference signal (34) and finally a composite interference signal (34) is obtained. A method of generating the image (36) can be realized by the following steps: since the wavelength ranges between the sub-spectra may overlap, the wavelength and frequency segments that do not contain repeated segments can be spliced together by the method of frequency axis splicing (32). Different spectral interference signals are detected by the pixels at different positions of the line scan camera after grating light splitting and lens focusing. Therefore, the wavelengths corresponding to each spectral interference signal are identified according to the coordinate positions of the detected signals, and the signals with repeated wavelengths are removed. Splicing non-repetitive but continuous frequency axes of wavelengths; on this basis, phase alignment is performed on each wavelength segmented interference signal (33), and spliced into a synthesized interference signal (34); finally, the synthesized interference signal (34) is spliced together. ) to perform spectral shaping (35), and obtain the synthesized image (36) through Fourier transform (42). The method of spectral shaping is to shape the interference signal of any envelope into a Gaussian-like envelope by multiplying it by a window function. The interference signal, the window function includes Hamming window function, Hanning window function, Gaussian window function and so on.5.根据权利要求4所述的分光谱频域相干断层成像系统，其特征在于，将两个不同分光谱所对应的不同波长范围的干涉信号(31)拼接为合成干涉信号(34)的方法具体包括：为了便于将不同分光谱所对应的不同波长范围的干涉信号(31)进行相位对齐，并进一步拼接成合成干涉信号(34)，在样本(10)成像距离之外、SDOCT系统所允许的成像范围之内放置一个半透明的单反射元件(15)，对两个分光谱干涉信号(31)分别提取其中的单反射元件对应的干涉信号，即提取单平面干涉信号(41)，得到两个分光谱单平面干涉信号，通过傅里叶变换(42)分别获得两个分光谱单平面干涉信号的相位，进行相位比对和匹配(43)，利用相位比对和匹配信息对其中一个分光谱干涉信号(31)进行线性波数插值(44)、傅里叶变换(42)、相位延迟补偿(45)、傅里叶逆变换(46)后，再与另一个分光谱干涉信号(31)进一步拼接为合成干涉信号(34)。5. The spectral-spectrum frequency-domain coherence tomography system according to claim 4, characterized in that, a method for splicing interference signals (31) of different wavelength ranges corresponding to two different sub-spectra into a composite interference signal (34) It specifically includes: in order to facilitate phase alignment of the interference signals (31) in different wavelength ranges corresponding to different sub-spectra, and further splicing into a composite interference signal (34), outside the imaging distance of the sample (10), the SDOCT system allows A translucent single-reflection element (15) is placed within the imaging range, and the interference signal corresponding to the single-reflection element is respectively extracted from the two spectral interference signals (31), that is, the single-plane interference signal (41) is extracted to obtain Two sub-spectral single-plane interference signals, respectively obtain the phase of the two sub-spectral single-plane interference signals through Fourier transform (42), perform phase comparison and matching (43), and use the phase comparison and matching information to compare one of them. After the spectral interference signal (31) is subjected to linear wavenumber interpolation (44), Fourier transform (42), phase delay compensation (45), and inverse Fourier transform (46), it is then combined with another spectral interference signal (31). ) are further spliced into a composite interference signal (34).6.根据权利要求5所述的分光谱频域相干断层成像系统，其特征在于，从分光谱干涉信号(31)中提取单平面干涉信号(41)得到分光谱单平面干涉信号的一种方法具体包括：首先对分光谱干涉信号(31)进行时域滤波(47)，由于线扫描相机采集到的信号是以经过光栅色散7得到的波长均匀排布的干涉信号，在后处理过程中通过线性波长到线性波数频率轴的插值(44)对时域滤波后的信号进行重采样，得到以波数均匀排布的频率轴对应的分光谱单平面干涉信号。6. The spectral frequency domain coherence tomography system according to claim 5, characterized in that, a method of extracting a single plane interference signal (41) from a spectral spectral interference signal (31) to obtain a spectral spectral single plane interference signal Specifically, it includes: firstly performing time-domain filtering (47) on the spectral interference signal (31), because the signal collected by the line scan camera is an interference signal with uniform wavelengths obtained by grating dispersion 7, which is passed through the post-processing process The linear wavelength to linear wavenumber frequency axis interpolation (44) resamples the time-domain filtered signal to obtain a subspectral single-plane interference signal corresponding to a frequency axis uniformly arranged in wavenumbers.7.根据权利要求5所述的分光谱频域相干断层成像系统，其特征在于，从分光谱干涉信号(31)中提取单平面干涉信号(41)得到分光谱单平面干涉信号的另一种方法具体包括：对分光谱干涉信号(31)先进行线性波长到线性波数频率轴的重采样插值(44)，然后通过傅里叶域滤波将线性波长到线性波数频率轴的重采样插值后的信号变换到傅里叶域，将单反射元件对应的干涉信号的频率保留，将其他频段滤除，再通过傅里叶反变换得到滤波后的分光谱单平面干涉信号。7. The spectral frequency domain coherence tomography system according to claim 5, wherein the single plane interference signal (41) is extracted from the spectral spectral interference signal (31) to obtain another kind of spectral spectral single plane interference signal. The method specifically includes: firstly performing a resampling interpolation (44) from a linear wavelength to a linear wavenumber frequency axis on the spectral interference signal (31), and then performing Fourier domain filtering to perform the resampling interpolation from the linear wavelength to the linear wavenumber frequency axis. The signal is transformed into the Fourier domain, the frequency of the interference signal corresponding to the single reflection element is retained, other frequency bands are filtered out, and then the filtered sub-spectral single-plane interference signal is obtained through the inverse Fourier transform.8.根据权利要求5所述的分光谱频域相干断层成像系统，其特征在于，所述半透明的单反射元件(15)为透明玻璃片。8 . The spectral frequency domain coherence tomography imaging system according to claim 5 , wherein the semitransparent single reflection element ( 15 ) is a transparent glass sheet. 9 .9.一种分光谱频域相干断层成像系统，其特征在于，该成像系统光源由n个带宽较窄的光源分别依次输入一个基于频域光学相干断层成像(SDOCT)系统的干涉仪，并依次检测对应的分光谱干涉信号(23)；通过数据后处理，将分光谱干涉信号(23)相位对齐拼接为一个合成干涉信号(34)，最后通过傅里叶变换得到物体不同深度解析的SDOCT合成图像，这样的合成图像其分辨率和信噪比优于单个光源作为SDOCT光源所得到的图像。9. A spectral frequency domain coherence tomography imaging system, characterized in that the light source of the imaging system is sequentially input into an interferometer based on a frequency domain optical coherence tomography (SDOCT) system from n light sources with narrower bandwidths, and sequentially. The corresponding spectral interference signal (23) is detected; the spectral interference signal (23) is phase-aligned and spliced into a composite interference signal (34) through data post-processing, and finally SDOCT composites of different depths of the object are obtained through Fourier transform image, the resolution and signal-to-noise ratio of such composite images are better than those obtained with a single light source as the SDOCT light source.10.根据权利要求9所述的分光谱频域相干断层成像系统，其特征在于，所述成像系统光源由n个不同波长范围的光源组成。其中n是1-10000之内的整数；假设第i个分光谱波长范围为λ_i1和λ_i2,其中1≤i≤n，则有λ_i1≤λ_i2，且λ_i1取值范围为380nm-1380nm，λ_i2取值范围为380nm-1380nm。10 . The spectral frequency domain coherence tomography imaging system according to claim 9 , wherein the imaging system light source is composed of n light sources with different wavelength ranges. 11 . where n is an integer within 1-10000; assuming that the i-th subspectral wavelength range is λ_i1 and λ_i2 , where 1≤i≤n, then λ_i1 ≤λ_i2 , and the value range of λ_i1 is 380nm- 1380nm, the value range of λ_i2 is 380nm-1380nm.

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