CN111627085B - Wavefront split-field curvature sensing method and device and self-adaptive OCT system - Google Patents
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Abstract
The application discloses a wavefront divides visual field curvature sensing method and device, self-adaptation OCT system, includes: the split spherical mirror receives and reflects parallel light returned by a sample arm in the self-adaptive OCT system; the image acquisition module receives the reflected parallel light and acquires far-field images of the sample arms with the same defocus amount on two sides of the focal plane for a plurality of times to obtain a light intensity distribution pattern; the network training module takes the subtraction of the two light intensity distribution patterns obtained each time as input, and takes the intrinsic Zernike polynomial coefficient as output to train the neural network; the wave-front information fitting module obtains the whole wave-front information through nonlinear fitting of a neural network according to the bilateral symmetry of the human eye aberration; the aberration correction module uses the wavefront information as feedback and corrects the aberration by adjusting the deformable mirror to obtain diffraction limited imaging. The method combines the wavefront sensing technology and the machine learning algorithm, can improve the imaging capability of the self-adaptive OCT, and reduces the influence of errors of an optical path and eyes.
Description
Technical Field
The invention relates to the technical field of optical imaging, in particular to a wavefront split-field curvature sensing method and device and a self-adaptive OCT system.
Background
Optical coherence tomography (Optical Coherence Tomography, OCT for short) is a novel imaging technique based on optical coherence properties, which is to analyze and detect the interference signals of back-scattered or reflected light and reference light of a biological tissue sample, perform tomography on the internal structure of the biological tissue sample, and obtain the tissue characteristics of an optical tomographic image so as to determine the target to be identified by diagnosis. Compared with the conventional imaging means, the OCT technology has unique advantages, the imaging effect is close to pathology, and the advantages of non-invasive non-radiation, live real-time observation, high resolution (16 microns), intra-tissue depth imaging, 3D image data and the like are achieved. OCT techniques have become an important tool for detecting retinal diseases.
In order to improve the transverse resolution of optical retina imaging, adaptive Optics (AO) is usually combined with OCT, but in the existing adaptive OCT (AO-OCT) technology, the influence of uniformity of wavefront sensing pupil illuminance is relatively large, and the method has the defects of easy inclination of the pupil, large dispersion influence, insufficient measuring range, low resolving robustness and the like.
Therefore, how to improve the imaging capability of adaptive OCT is a technical problem to be solved by those skilled in the art.
Disclosure of Invention
In view of the above, the present invention aims to provide a wavefront split-field curvature sensing method and device, and an adaptive OCT system, which can improve the imaging capability of the adaptive OCT, reduce the influence of errors of the optical path and the eye, and improve the robustness. The specific scheme is as follows:
a wavefront split field curvature sensing method for an adaptive OCT system, comprising:
the split spherical mirror receives and reflects parallel light returned from a sample arm in the adaptive OCT system;
the image acquisition module receives the reflected parallel light and acquires far-field images of the sample arms with the same defocus amount on two sides of the focal plane for a plurality of times to obtain a light intensity distribution pattern;
the network training module takes the subtraction of the two obtained light intensity distribution patterns as input and takes the intrinsic Zernike polynomial coefficient as output to train the neural network;
the wavefront information fitting module obtains distorted whole wavefront information through trained nonlinear fitting of the neural network according to the bilateral symmetry of the human eye aberration;
an aberration correction module corrects aberration by adjusting a deformable mirror in the adaptive OCT system with the obtained wavefront information as feedback to obtain diffraction limited imaging.
Preferably, in the wavefront split-field curvature sensing method provided by the embodiment of the present invention, far-field images of a sample arm having the same defocus amount at two sides of a focal plane are respectively acquired, and the method specifically includes:
and respectively acquiring far-field images of the sample arms with the same defocus amount at two sides of the focal plane in a single exposure mode.
Preferably, in the wavefront split-field curvature sensing method provided by the embodiment of the present invention, the neural network uses a wavelet function as a hidden layer activation function.
Preferably, in the wavefront split-field curvature sensing method provided by the embodiment of the present invention, the method further includes:
the spectroscope or the reflecting mirror receives the parallel light reflected by the split spherical mirror and reflects the parallel light to the image acquisition module.
Preferably, in the wavefront split-field curvature sensing method provided by the embodiment of the present invention, the image acquisition module is a CCD camera.
Preferably, in the wavefront split-field curvature sensing method provided by the embodiment of the present invention, the image acquisition module moves through a guide rail installed below the image acquisition module.
The embodiment of the invention also provides a wavefront split-field curvature sensing device, which comprises:
the split spherical mirror is used for receiving and reflecting parallel light returned by a sample arm in the adaptive OCT system;
the image acquisition module is used for receiving the reflected parallel light and respectively acquiring far-field images of the sample arms with the same defocus amount on two sides of the focal plane for a plurality of times to obtain a light intensity distribution pattern;
the network training module is used for subtracting two obtained light intensity distribution patterns from each other to be input, and training a neural network by taking the intrinsic Zernike polynomial coefficient as output;
the wave-front information fitting module is used for obtaining distorted whole wave-front information through trained nonlinear fitting of the neural network according to the bilateral symmetry of the human eye aberration;
an aberration correction module for correcting aberration by adjusting a deformable mirror in the adaptive OCT system with the obtained wavefront information as feedback to obtain diffraction limited imaging.
Preferably, in the wavefront split-field curvature sensing device provided by the embodiment of the present invention, the device further includes:
and the spectroscope or the reflecting mirror is used for receiving the parallel light reflected by the split spherical mirror and reflecting the parallel light to the image acquisition module.
Preferably, in the wavefront split-field curvature sensing device provided by the embodiment of the present invention, the image acquisition module is a CCD camera; the CCD camera is moved by a guide rail installed below the CCD camera.
The embodiment of the invention also provides an adaptive OCT system, which comprises: the low-coherence light source, the optical fiber coupler, the reference arm, the sample arm and the spectrometer are used for providing weak-coherence light and are connected through optical fibers; the sample arm comprises a first spectroscope, a deformable mirror and a scanning mechanism, and also comprises the wavefront split-view field curvature sensing device provided by the embodiment of the invention; wherein,,
the optical fiber coupler is used for dividing the weak coherent light into a first light beam and a second light beam, wherein the first light beam enters the sample arm, and the second light beam enters the reference arm;
the reference arm is used for reflecting the first light beam and returning the first light beam back to the optical fiber coupler;
the sample arm is used for focusing the second light beam to the deformable mirror through the first spectroscope, reflecting the second light beam to the scanning mechanism through the deformable mirror, scanning the fundus to be detected through the scanning mechanism, returning the scanned light back along an original path, dividing the scanned light beam into two parts after the scanned light beam reaches the first spectroscope, reflecting one part of the scanned light beam to the wavefront split-view curvature sensing device to obtain distorted whole wavefront information, taking the obtained wavefront information as feedback, correcting aberration by adjusting the deformable mirror in the adaptive OCT system, and enabling the other part of the scanned light beam to enter the optical fiber coupler;
the spectrometer is used for receiving light reflected by the reference arm and the sample arm and collecting interference patterns.
From the above technical solution, the wavefront split-field curvature sensing method and device, and the adaptive OCT system provided by the present invention include: the split spherical mirror receives and reflects parallel light returned by a sample arm in the self-adaptive OCT system; the image acquisition module receives the reflected parallel light and acquires far-field images of the sample arms with the same defocus amount on two sides of the focal plane for a plurality of times to obtain a light intensity distribution pattern; the network training module takes the subtraction of the two light intensity distribution patterns obtained each time as input, and takes the intrinsic Zernike polynomial coefficient as output to train the neural network; the wave-front information fitting module obtains distorted whole wave-front information through trained neural network nonlinear fitting according to the bilateral symmetry of the human eye aberration; the aberration correction module corrects the aberration by adjusting a deformable mirror in the adaptive OCT system with the obtained wavefront information as feedback to obtain diffraction limited imaging.
The invention combines the wavefront sensing technology and the machine learning algorithm, estimates the change of the wavefront curvature through the light intensity distribution of the split spherical mirror before and after the focus, calculates the wavefront information through the nonlinear fitting of the neural network, corrects the aberration through the wavefront information, improves the rapid aberration measurement and the chromatic aberration correction in the self-adaptive OCT imaging process, reduces the tissue interference, realizes the diffraction limit imaging, can rapidly improve the imaging capability of the self-adaptive OCT, reduces the influence of errors of an optical path and eyes, improves the robustness, and has good application prospect.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the related art, the drawings that are required to be used in the embodiments or the related technical descriptions will be briefly described, and it is apparent that the drawings in the following description are only embodiments of the present invention, and other drawings may be obtained according to the provided drawings without inventive effort for those skilled in the art.
FIG. 1 is a flow chart of a wavefront split field curvature sensing method provided by an embodiment of the present invention;
FIG. 2 is a schematic diagram of light transmission between a split spherical mirror and a CCD camera according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of curvature sensing provided by an embodiment of the present invention;
FIG. 4 is a schematic diagram of data resolution provided in an embodiment of the present invention;
FIG. 5 is a schematic structural diagram of a wavefront field curvature sensing device according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of an adaptive OCT system according to an embodiment of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The invention provides a wavefront split-field curvature sensing method, which is shown in fig. 1 and comprises the following steps:
s101, receiving parallel light returned from a sample arm in the self-adaptive OCT system by a split spherical mirror and reflecting the parallel light;
it should be noted that, the split spherical mirror is formed by dividing a standard spherical mirror into two halves, that is, the split spherical mirror is divided into two parts, and fig. 2 shows a structure of the split spherical mirror 11, which can be imaged before and after focusing respectively;
s102, an image acquisition module receives the reflected parallel light and acquires far-field images of a sample arm, which are formed by the same defocus amount, on two sides of a focal plane (namely before and after focusing) for a plurality of times, so as to obtain a light intensity distribution pattern;
in particular implementations, as shown in FIG. 2, the image acquisition module 12 may be a CCD camera. In practical application, the image acquisition module 12 can move through a guide rail arranged below the image acquisition module, namely, after parallel light reflected by the split spherical mirror enters the CCD camera, two images can be ensured to be one focus before the other focus through the movement of the guide rail;
s103, the network training module takes the subtraction of two light intensity distribution patterns obtained each time as input, takes the intrinsic Zernike polynomial coefficient as output, and trains the neural network;
it should be noted that when the fitting order is increased, the problem of serious rank deficiency, or that is, the same result can be achieved by fewer orders, since the linear correlation is too strong before, in order to fit certain frequency components to it, a very high order needs to be increased, and an excessive high order can cause matrix morbidity, and the current highest fitting can only use 16-18 orders or use nonlinear optimization to process the result. The invention uses an 'eigenmode' to solve the problem that a Zernike polynomial on a semicircular aperture is orthogonalized, and an aberration is expressed by an eigen Zernike polynomial coefficient based on the substrate by adopting the eigenmode;
s104, the wave-front information fitting module obtains distorted whole wave-front information through trained neural network nonlinear fitting according to the bilateral symmetry of the human eye aberration;
s105, using the obtained wavefront information as feedback, the aberration correction module corrects the aberration by adjusting a deformable mirror in the adaptive OCT system so as to obtain diffraction limit imaging.
In the wavefront split-view field curvature sensing method provided by the embodiment of the invention, a wavefront sensing technology and a machine learning algorithm are combined, the change of the wavefront curvature is estimated through the light intensity distribution of the split spherical mirror before and after the focus, the wavefront information is calculated through nonlinear fitting of a neural network, the wavefront information is used for correcting the aberration, the rapid aberration measurement and chromatic aberration correction in the self-adaptive OCT imaging process are improved, the tissue interference is reduced, the diffraction limit imaging is realized, the imaging capability of the self-adaptive OCT can be rapidly improved, the influence of errors of an optical path and eyes is reduced, the robustness is improved, and the application prospect is good.
The curvature sensing principle of the wavefront split-field curvature sensing method according to the embodiment of the present invention will be described in detail below by taking fig. 3 as an example:
the wavefront at the pupil is locally changed in curvature, and the light intensity distribution of the corresponding in-focus image and out-of-focus image is correspondingly changed. According to the transmission equation of the near-field electromagnetic wave, the wave front information can be calculated as shown in the formula (1):
wherein,,
for strength (I)>
Is phase, is a gradient operator, and the obtained result is slope, is 2 The result is curvature, which is the laplace operator. />
Is the intra-pupil coordinate,/->
As pupil coordinates in the image plane, γ=1 is defaulted in the above formula. It can be seen that the results are related to the slope curvature.
For an adaptive optics system, the defocus amount is generally only a few focal depths, and the defocus star image is very close to the pupil shape, and after subtraction, it can be considered that:
wherein R is the radius of the light spot.
Formula (1) is thus approximated by formula (2):
wherein P is 1 And P 2 Is two symmetrical planes with defocus amount l at two sides of the focal plane, and Deltaz is P 1 P 2 The distance of the conjugate position relative to the entrance pupil is shown in formula (3):
Δz＝f(f-l)/l (3)
is provided with
The formula (4) can be obtained by substituting the formula (2).
Solving the poisson equation according to the formula (4), wherein the deformable mirror in the adaptive OCT system can automatically converge towards the surface shape meeting the poisson equation; here, the wavefront of the full aperture is estimated using half the aperture.
Through fast Fourier transform
Therefore, can obtain:
with P 1 For example, the conversion relationship between the focal plane and the pupil plane is shown in formula (6), and the relationship between the focal plane and the pupil plane is defined as P 1 The light intensity distribution obtained by the position is
At P 2 The light intensity distribution obtained by the position is +.>
In a specific implementation, in the wavefront split-field curvature sensing method provided by the embodiment of the present invention, sample arm far-field images with the same defocus amount at two sides of a focal plane are respectively acquired, and the method specifically includes: and respectively acquiring far-field images of the sample arms with the same defocus amount at two sides of the focal plane in a single exposure (single-shot) mode. The method can realize acquisition of front and back images of the focal plane without moving parts, realizes simultaneous measurement, and finally obtains complete wavefront distortion information through a synthesis algorithm based on sub-field detection of the extended target of the bottom of the eye by utilizing the characteristic that curvature sensing is less affected by aperture.
In a specific implementation, in the wavefront field curvature sensing method provided by the embodiment of the present invention, the neural network may use a wavelet function as a hidden layer activation function. The wavelet neural network combines the characteristics of multi-scale representation of wavelet transformation, and simultaneously maintains the characteristics of good generalization capability and strong nonlinear mapping capability of the neural network.
It should be appreciated that machine learning is a branch of artificial intelligence, and is aimed at autonomously learning in a large amount of empirical data, summarizing and finding the relationships between variables in a system, summarizing and using algorithms to continuously improve weight values, and finally predicting unknown data. When the existing rules and formulas can not describe common aberration and systematic errors, the machine learning model is built to process a large amount of data, so that great flexibility and adaptability are shown. As shown in FIG. 4, the present invention rotates the two light intensity distribution patterns, aligns them, then subtracts them, takes the subtracted two light intensity distribution patterns as input, and takes the intrinsic Zernike polynomial coefficient as output to train the neural network.
In addition, it should be noted that the invention builds a model of systematic errors (gravity, temperature, airflow, vibration, actuator errors, optical element surface shape errors, polarization errors, light intensity flickering) based on the deep learning algorithm end-to-end, realizes calibration of the system, and reduces the pressure of hardware realization.
In a specific implementation, the wavefront field curvature sensing method provided by the embodiment of the present invention may further include: the spectroscope or the reflecting mirror receives the parallel light reflected by the split spherical mirror and reflects the parallel light to the image acquisition module.
Based on the same inventive concept, the embodiment of the invention also provides a wavefront split-field curvature sensing device, and because the principle of solving the problem of the wavefront split-field curvature sensing device is similar to that of the wavefront split-field curvature sensing method, the implementation of the wavefront split-field curvature sensing device can be referred to the implementation of the wavefront split-field curvature sensing method, and the repetition is omitted.
In specific implementation, the wavefront field curvature sensing device provided by the embodiment of the present invention, as shown in fig. 5, specifically includes:
a split spherical mirror 11 for receiving and reflecting parallel light returned from a sample arm in the adaptive OCT system;
the image acquisition module 12 is used for receiving the reflected parallel light and respectively acquiring far-field images of the sample arms with the same defocus amount on two sides of the focal plane for a plurality of times to obtain a light intensity distribution pattern;
the network training module 13 is configured to train the neural network by subtracting the two light intensity distribution patterns obtained each time as input and by taking the intrinsic zernike polynomial coefficient as output;
the wavefront information fitting module 14 is configured to obtain distorted entire wavefront information through nonlinear fitting of the trained neural network according to bilateral symmetry of the human eye aberration;
an aberration correction module 15 for correcting aberration by adjusting a deformable mirror in the adaptive OCT system with the obtained wavefront information as feedback to obtain diffraction limited imaging.
In the wavefront split view field curvature sensing device provided by the embodiment of the invention, the interaction of the split spherical mirror and the four modules can be combined with a wavefront sensing technology and a machine learning algorithm, so that the rapid aberration measurement and chromatic aberration correction in the self-adaptive OCT imaging process are improved, the tissue interference is reduced, the diffraction limit imaging is realized, the imaging capability of the self-adaptive OCT is further improved, the influence of errors of an optical path and eyes is reduced, and the robustness is improved.
In a specific implementation, the wavefront field curvature sensing device provided by the embodiment of the present invention may further include: the spectroscope or the reflecting mirror is used for receiving the parallel light reflected by the split spherical mirror and reflecting the parallel light to the image acquisition module.
In a specific implementation, in the wavefront field curvature sensing device provided by the embodiment of the present invention, the image acquisition module may be a CCD camera; in practical applications, the CCD camera may be moved by a guide rail mounted thereunder.
For more specific working procedures of the above modules, reference may be made to the corresponding contents disclosed in the foregoing embodiments, and no further description is given here.
Based on the same inventive concept, an embodiment of the present invention further provides an adaptive OCT system, as shown in fig. 6, including: a low coherence light source 1 for providing weak coherence light, a fiber coupler 2, a reference arm 3, a sample arm and a spectrometer 4, which are connected to each other by a fiber; the sample arm comprises a first spectroscope 10, a deformable mirror 20 and a scanning mechanism 30, and further comprises the wavefront split-field curvature sensing device 40 provided by the embodiment of the invention; wherein,,
an optical fiber coupler 2 for dividing the weak coherent light into a first beam and a second beam, the first beam entering the sample arm and the second beam entering the reference arm 3;
a reference arm 3 for reflecting the first light beam back into the optical fiber coupler 2;
the sample arm is used for focusing the second light beam to the deformable mirror 20 through the first spectroscope 10, reflecting the second light beam to the scanning mechanism 30 through the deformable mirror 20, scanning the fundus to be detected through the scanning mechanism 30, returning the scanned light beam back along the original path, dividing the scanned light beam into two parts after the scanned light beam reaches the first spectroscope 10, reflecting one part of the scanned light beam to the wavefront split-field curvature sensing device 40 to obtain distorted whole wavefront information, taking the obtained wavefront information as feedback, correcting aberration by adjusting the deformable mirror 20 in the adaptive OCT system, and entering the other part of the scanned light beam into the optical fiber coupler 2;
and a spectrometer 4 for receiving the light reflected back from the reference arm 3 and the sample arm and collecting the interference pattern.
Specifically, the invention adopts a frequency domain optical coherence tomography (Spectral Domain Optical Coherence Tomography, SDOCT) basic architecture, weak infrared laser penetrates the subcutaneous tissue of the fundus to be detected, different tissue layers refract optical signals due to structural difference and interfere with each other, and the fundus to be detected is recombined by an algorithm after returning to an optical host. The SDOCT can obtain the characteristic information of all depth positions without longitudinal scanning, has high imaging speed, and has high imaging capability, small influence of errors of an optical path and eyes per se, high robustness, corrected interference patterns finally obtained, no chromatic aberration and high accuracy due to the arrangement of the wavefront split-view field curvature sensing device.
In this specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, so that the same or similar parts between the embodiments are referred to each other. For the device and the system disclosed in the embodiments, the description is relatively simple, and the relevant parts refer to the description of the method part because the device and the system correspond to the method disclosed in the embodiments.
Those of skill would further appreciate that the various illustrative modules and algorithm steps described in connection with the embodiments disclosed herein may be implemented as electronic hardware, computer software, or combinations of both, and that the various illustrative components and steps have been described above generally in terms of functionality in order to clearly illustrate the interchangeability of hardware and software. Whether such functionality is implemented as hardware or software depends upon the particular application and design constraints imposed on the solution. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present application.
The steps of a method or algorithm described in connection with the embodiments disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. The software modules may be disposed in Random Access Memory (RAM), memory, read Only Memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.
The embodiment of the invention provides a wavefront split-field curvature sensing method and device and an adaptive OCT system, which comprise the following steps: the split spherical mirror receives and reflects parallel light returned by a sample arm in the self-adaptive OCT system; the image acquisition module receives the reflected parallel light and acquires far-field images of the sample arms with the same defocus amount on two sides of the focal plane for a plurality of times to obtain a light intensity distribution pattern; the network training module takes the subtraction of the two light intensity distribution patterns obtained each time as input, and takes the intrinsic Zernike polynomial coefficient as output to train the neural network; the wave-front information fitting module obtains distorted whole wave-front information through trained neural network nonlinear fitting according to the bilateral symmetry of the human eye aberration; the aberration correction module corrects the aberration by adjusting a deformable mirror in the adaptive OCT system with the obtained wavefront information as feedback to obtain diffraction limited imaging. The wavefront sensing technology and the machine learning algorithm are combined, the change of the wavefront curvature is estimated through the light intensity distribution of the split spherical mirror before and after the focus, the wavefront information is calculated through nonlinear fitting of a neural network, the wavefront information is used for correcting the aberration, the rapid aberration measurement and chromatic aberration correction in the self-adaptive OCT imaging process are improved, the tissue interference is reduced, the diffraction limit imaging is realized, the imaging capability of the self-adaptive OCT can be rapidly improved, the influence of errors of an optical path and eyes is reduced, the robustness is improved, and the application prospect is good.
Finally, it is further noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.
The wavefront split field curvature sensing method and device and the adaptive OCT system provided by the invention are described in detail, and specific examples are applied to illustrate the principles and the implementation modes of the invention, and the description of the above examples is only used for helping to understand the method and the core idea of the invention; meanwhile, as those skilled in the art will have variations in the specific embodiments and application scope in accordance with the ideas of the present invention, the present description should not be construed as limiting the present invention in view of the above.
Claims (10)
1. A wavefront split field curvature sensing method for an adaptive OCT system, comprising:
the split spherical mirror receives and reflects parallel light returned from a sample arm in the adaptive OCT system;
the image acquisition module receives the reflected parallel light and acquires far-field images of the sample arms with the same defocus amount on two sides of the focal plane for a plurality of times to obtain a light intensity distribution pattern;
the network training module takes the subtraction of the two obtained light intensity distribution patterns as input and takes the intrinsic Zernike polynomial coefficient as output to train the neural network;
the wavefront information fitting module obtains distorted whole wavefront information through trained nonlinear fitting of the neural network according to the bilateral symmetry of the human eye aberration;
an aberration correction module corrects aberration by adjusting a deformable mirror in the adaptive OCT system with the obtained wavefront information as feedback to obtain diffraction limited imaging.
2. The method according to claim 1, wherein the sample arm far-field images with the same defocus amount on both sides of the focal plane are acquired respectively, specifically comprising:
and respectively acquiring far-field images of the sample arms with the same defocus amount at two sides of the focal plane in a single exposure mode.
3. The wavefront split-field curvature sensing method of claim 2, wherein the neural network uses a wavelet function as a hidden layer activation function.
4. A wavefront split field of view curvature sensing method as in claim 3, further comprising:
the spectroscope or the reflecting mirror receives the parallel light reflected by the split spherical mirror and reflects the parallel light to the image acquisition module.
5. The method of claim 1, wherein the image acquisition module is a CCD camera.
6. The method of claim 5, wherein the image acquisition module is moved by a rail mounted thereunder.
7. A wavefront split field curvature sensing device for an adaptive OCT system, comprising:
the split spherical mirror is used for receiving and reflecting parallel light returned by a sample arm in the adaptive OCT system;
the image acquisition module is used for receiving the reflected parallel light and respectively acquiring far-field images of the sample arms with the same defocus amount on two sides of the focal plane for a plurality of times to obtain a light intensity distribution pattern;
the network training module is used for subtracting two obtained light intensity distribution patterns from each other to be input, and training a neural network by taking the intrinsic Zernike polynomial coefficient as output;
the wave-front information fitting module is used for obtaining distorted whole wave-front information through trained nonlinear fitting of the neural network according to the bilateral symmetry of the human eye aberration;
an aberration correction module for correcting aberration by adjusting a deformable mirror in the adaptive OCT system with the obtained wavefront information as feedback to obtain diffraction limited imaging.
8. The wavefront split field of view curvature sensing device of claim 7, further comprising:
and the spectroscope or the reflecting mirror is used for receiving the parallel light reflected by the split spherical mirror and reflecting the parallel light to the image acquisition module.
9. The wavefront field of view curvature sensing device of claim 8, wherein the image acquisition module is a CCD camera; the CCD camera is moved by a guide rail installed below the CCD camera.
10. An adaptive OCT system, comprising: the low-coherence light source, the optical fiber coupler, the reference arm, the sample arm and the spectrometer are used for providing weak-coherence light and are connected through optical fibers; the sample arm comprising a first beam splitter, a deformable mirror, a scanning mechanism, and a wavefront split field curvature sensing device as claimed in any one of claims 7 to 9; wherein,,
the optical fiber coupler is used for dividing the weak coherent light into a first light beam and a second light beam, wherein the first light beam enters the sample arm, and the second light beam enters the reference arm;
the reference arm is used for reflecting the first light beam and returning the first light beam back to the optical fiber coupler;
the sample arm is used for focusing the second light beam to the deformable mirror through the first spectroscope, reflecting the second light beam to the scanning mechanism through the deformable mirror, scanning the fundus to be detected through the scanning mechanism, returning the scanned light back along an original path, dividing the scanned light beam into two parts after the scanned light beam reaches the first spectroscope, reflecting one part of the scanned light beam to the wavefront split-view curvature sensing device to obtain distorted whole wavefront information, taking the obtained wavefront information as feedback, correcting aberration by adjusting the deformable mirror in the adaptive OCT system, and enabling the other part of the scanned light beam to enter the optical fiber coupler;
the spectrometer is used for receiving light reflected by the reference arm and the sample arm and collecting interference patterns.
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