CN110487425A - A kind of wavefront sensing methods and its device based on defocus type light-field camera - Google Patents

Abstract

The invention discloses a wavefront detection device of a defocused light field camera, comprising: a converging lens for converging the wavefront to be measured; a microlens array for converging the wavefront to be measured on the converging lens The previously formed light spot is divided; CCD detector is used for accepting the light spot array information formed after microlens array divides light spot, and the distance between described microlens array and described CCD detector is equal to described microlens unit focal length; The microlens array is located at the focal distance of the converging lens at the defocus amount f _defcous ; the defocus amount is f _defcous =r·n·f, and n is the corresponding CCD of a microlens unit in the microlens array The number of pixels of the detector, f is the focal length of the microlens unit, and r is the number of microlens units occupied by the light spot of the equivalent sub-aperture. The invention also discloses a wavefront detection method based on a defocused light field camera. The invention can optimize the field of view, dynamic range and measurement accuracy of wavefront detection.

Description

A wavefront detection method and device based on a defocused light field camera

technical field

The invention relates to the field of wavefront detection, in particular to a wavefront detection method and a device thereof.

Background technique

As a new optical technology developed in recent decades, adaptive optics uses optoelectronic devices to measure the dynamic error of the wavefront in real time, and calculates and controls it through a high-speed computer system, so that the active device can correct the wavefront in real time. Adaptive optics enables the optical system to automatically adapt to changes in external conditions and maintain a good working condition. It has important applications in the fields of high-resolution imaging and laser transmission.

The wavefront sensor is an important part of the adaptive optics system, and the adaptive optics technology mainly performs wavefront sensing by measuring the first derivative (slope) or second derivative (curvature) of the wavefront distortion. The Shack-Hartmann sensor is currently the most widely used wavefront sensor. It uses a microlens array to segment the incident wavefront, measures the average slope of the wavefront in each sub-aperture, and then restores the wavefront aberration. The Shack-Hartmann sensor has many advantages such as compact structure, high light energy utilization rate, and the ability to work on continuous or pulsed targets, but at the same time, it also has a small dynamic range, insufficient weak light detection capability, and difficulty in adjusting wavefront measurements. defects such as spatial resolution. In 1996, Ragazzoni proposed a quadrangular pyramid wavefront sensor. The basic principle is that the light beam is focused on the apex of the quadrangular pyramid and then split, and the local slope of the wavefront is calculated by the intensity difference between the four sub-pupil images on the detection surface. The quadrangular pyramidal wavefront sensor has a higher spatial resolution than the Hartmann sensor, and its sensitivity and weak light detection ability are more prominent during closed-loop correction.

In addition, in 2003, Clare and Lane of New Zealand proposed a method of placing a microlens array on the rear focal plane of the objective lens and combining a CCD photodetector for wavefront detection. However, the wavefront detection method in the prior art has a certain size of the microlens aperture (usually several times the diffraction limit), and the measurement accuracy of the wavefront sensor of the light field camera is restricted by the signal saturation phenomenon, so it can only perform Relatively rough wavefront measurement, and the problem that the application of defocused wavefront sensors in adaptive optics technology is limited to a certain extent.

Contents of the invention

The present invention aims to solve one of the technical problems in the related art at least to a certain extent. An object of the present invention is to provide a wavefront detection device based on a defocused light field camera with high measurement accuracy, simple structure, and conforming to the development trend of adaptive optics.

Therefore, the second object of the present invention is to provide a wavefront detection method for a defocused light field camera with a large field of view, a large dynamic range, high measurement accuracy, a simple structure, and in line with the development trend of adaptive optics.

The technical scheme adopted in the present invention is:

In a first aspect, the present invention provides a wavefront detection device based on a defocused light field camera, including:

a converging lens for converging the wavefront to be measured;

A microlens array, configured to divide the spot formed by the converging lens converging the wavefront to be measured;

The CCD detector is used to receive the light spot array information formed after the microlens array divides the light spot, and the distance between the microlens array and the CCD detector is equal to the focal length of the microlens unit;

The microlens array is located at the defocus amount f _defcous with the focal distance of the converging lens _; The number of pixels of the CCD detector, f is the focal length of the microlens unit, and r represents the number of microlens units occupied by the light spot of the equivalent sub-aperture.

Further, it also includes an optical matching system, the optical matching system is arranged at the input end of the converging lens, and is used to match the wavefront to be measured to the converging lens.

Further, a processing module is also included, the processing module is used to reorganize the spot array to obtain an equivalent sub-aperture image, and after calculating the centroid offset of the measured wavefront through the equivalent sub-aperture image, use the reconstruction The matrix calculates the Zernike aberration coefficients of each order of the wavefront to be measured to obtain the phase distribution of the wavefront to be measured.

Further, it also includes calculating the Zernike aberration coefficient solving algorithm of each order of the wavefront to be measured:

(1) Input the ideal plane wave into the wavefront detection device, calculate the centroid position S _0x , S _0y in each sub-aperture after recombining the equivalent sub-aperture image;

(2) Assuming that the wavefront to be measured can be fully represented by the first k-order Zernike aberrations, the first k-order Zernike aberrations are sequentially generated as the input of the wavefront detection device, and the wavefront detection device is recombined into an equivalent sub-aperture image, and each sub-aperture image is calculated. The position of the center of mass in the aperture and the offset of the center of mass relative to the plane wave entry ΔS _kx (n)=S _kx (n)-S _0x (n), ΔS _ky (n)=S _ky (n)-S _0y (n );

(3) Arrange the centroid offsets of Zernike aberrations of each order obtained in step (2) according to the form of formula (1), and obtain the restoration matrix D ^2n×k .

(4) calculate the generalized inverse matrix of restoration matrix, obtain reconstruction matrix D ⁺ ;

(5) When the wavefront to be measured is incident on the wavefront sensor of the light field camera, the CCD image is reorganized into the sub-aperture image in the manner described in step 2 and the centroid offset is calculated to obtain the vector

G＝[ΔS _x (1), ΔS _y (1), ΔS _x (2), ΔS _y (2),...ΔS _x (n), ΔS _y (n)] ^T (2)

(6) The Zernike aberration coefficients of each order included in the wavefront to be measured can be obtained by A=D ⁺ ·G.

Further, the F-number of the microlens element is an integer multiple of the F-number of the converging lens.

Further, the pixel size of the CCD detector matches the aperture of a single microlens element.

Further, the aperture of the microlens unit is an integer multiple of the pixel size of the CCD detector.

Further, the focal lengths of each microlens unit in the microlens array are equal, the fill factor of the microlens unit is greater than 99%, the transmittance is greater than 99%, and the distance between the microlens array and the CCD detector is Equal to the focal length of the microlens unit.

Further, the microlens array is a refractive microlens array or a reflective microlens array or a binary diffraction element.

In a second aspect, the present invention provides a wavefront detection method for a defocused light field camera, including:

Use a converging lens to converge the wavefront to be measured;

Using a microlens array to divide the light spot formed by the converging lens to converge the wavefront to be measured to form a light spot array, the microlens array includes a plurality of microlens units;

Using a CCD detector to receive the optical signal of the spot array;

The defocus of described converging lens and described lens array is f _defcous =r n f, n is the pixel number of the corresponding CCD detector of a microlens unit in the microlens array, and f is the focal length of microlens unit , r represents the number of microlens units occupied by the light spot of the equivalent sub-aperture.

Further, it also includes:

The optical signal of the spot array is received by the CCD detector, and recombined to obtain an equivalent sub-aperture image. After calculating the centroid offset of the wavefront to be measured through the equivalent sub-aperture image, the reconstruction matrix is used to calculate the The Zernike aberration coefficients of each order of the wavefront are measured to obtain the phase distribution of the wavefront to be measured.

Further, it also includes:

Said utilizing the reconstruction matrix to calculate each order Zernike aberration coefficient of the wavefront to be measured, to obtain the phase distribution of the wavefront to be measured, specifically includes sub-steps:

(1) Input the ideal plane wave into the wavefront sensor of the light field camera, calculate the centroid position S _0x , S _0y in each sub-aperture after recombining the equivalent sub-aperture image;

(2) Assuming that the wavefront to be measured can be fully represented by the first k-order Zernike aberrations, the first k-order Zernike aberrations are sequentially generated as the input of the wavefront sensor of the light field camera, and the reconstructed light field camera image is an equivalent sub-aperture image, calculated The position of the center of mass in each sub-aperture and the offset of the center of mass relative to the plane wave entrance ΔS _kx (n)=S _kx (n)-S _0x (n), ΔS _ky (n)=S _ky (n)-S _0y (n);

(3) arrange the centroid offsets of each order of Zernike aberrations obtained in step (2) according to the form of formula (1), and obtain the restoration matrix D ^{2n × k} ;

(4) calculate the generalized inverse matrix of restoration matrix, obtain reconstruction matrix D ⁺ ;

(5) When the wavefront to be measured is incident on the wavefront sensor of the light field camera, the CCD image is reorganized into the sub-aperture image in the manner described in step 2 and the centroid offset is calculated to obtain the vector

G＝[ΔS _x (1), ΔS _y (1), ΔS _x (2), ΔS _y (2),...ΔS _x (n), ΔS _y (n)] ^T (2)

(6) The Zernike aberration coefficients of each order included in the wavefront to be measured can be obtained by A=D ⁺ ·G.

The beneficial effects of the present invention are:

The present invention overcomes the problems in the prior art that the aperture of the microlens has a certain size (usually several times the diffraction limit) and the measurement accuracy of the wavefront sensor of the light field camera is saturated by the signal by adopting the defocusing method of the microlens array. Due to the restriction of the phenomenon, the technical problem of only rough wavefront measurement is achieved, and the measurement of the wavefront with a large field of view, a large dynamic range, and high measurement accuracy is realized with a simple optical system.

Description of drawings

Fig. 1 is a structural schematic diagram of a wavefront detection method based on a defocused light field camera of the present invention;

Fig. 2 is a cross-sectional view of a wavefront detection method based on a defocused light field camera of the present invention;

Fig. 3 is a structural schematic diagram of data reorganization of a wavefront detection method based on a defocused light field camera according to the present invention;

Fig. 4 is a structural schematic diagram of calculating the defocus amount of the microlens array based on the wavefront detection method of the defocused light field camera of the present invention;

Fig. 5A is the detection diagram of inputting the wavefront to be measured;

Fig. 5B is a schematic diagram of the distribution of Zernike polynomial coefficients input to the wavefront to be measured;

FIG. 6A is a detection diagram of reconstructing the wavefront to be measured by an existing light field camera;

Fig. 6B is a schematic distribution diagram of a comparison diagram of the Zernike polynomial coefficients of the wavefront reconstruction of the existing light field camera and the Zernike polynomial coefficients of the wavefront to be measured;

FIG. 7A is a detection diagram of reconstructing the wavefront to be measured by a defocused light field camera;

FIG. 7B is a schematic diagram showing the distribution of the Zernike polynomial coefficients of the wavefront reconstruction of the defocused light field camera and the Zernike polynomial coefficients of the wavefront to be measured.

Detailed ways

It should be noted that, in the case of no conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

F number: the reciprocal of the relative aperture.

Please refer to FIG. 1 . FIG. 1 is a schematic structural diagram of a wavefront detection device based on a defocused light field camera according to the present invention. It specifically includes an optical matching system 1 , a converging lens 2 , a microlens array 3 , and a CCD detector 4 .

A converging lens 2 is set at the output end of the optical matching system 1, and the output surface of the optical matching system 1 coincides with the front focal plane of the converging lens 2; a microlens array 3 is set near the rear focal plane of the converging lens 2, and there is A certain amount of defocus is set at the output end of the microlens array 3 to a CCD detector 4 for receiving optical signals. The microlens array 3 includes a plurality of identical microlens units arranged on the same plane at a certain period.

The optical matching system 1 is used for pre-modulating the wavefront to be measured, such as modulating the wavefront to be measured into parallel light and entering it into the converging lens 2 . The F-number of the microlens array 3 (i.e. the reciprocal of the relative aperture) matches the F-number of the converging lens 2 to ensure that the pixels under the microlens are fully utilized and do not generate data aliasing. The CCD detector 4 and the microlens array 3 The distance between is equal to the focal length of the above-mentioned microlens. The wavefront distortion to be measured passes through the optical matching system 1 and the converging lens 2 to form a spot of a certain area on the microlens array 3 , and the microlens array 3 divides the spot and images it on the CCD detector 4 as a spot array. The equivalent sub-aperture image can be obtained by reorganizing the image received by the CCD detector 4. After calculating the centroid offset of the measured wavefront, use the reconstruction matrix to calculate

Please refer to FIG. 2 , which is a cross-sectional view of a wavefront detection device based on a defocused light field camera. The light passing through the front focal point A of the converging lens 2 passes through the converging lens 2 and the microlens array 3 in sequence, and irradiates the CCD detector 4 after being refracted, and illuminates the pixels on the CCD detector 4 . Wherein no matter how the incident direction of the light changes, the propagation directions of the light passing through the point A are parallel to each other after being refracted by the microlens. That is, the relative positions of the illuminated pixels on the CCD detector 4 and the corresponding microlens units of the microlens array 3 are fixed.

In other modified embodiments, other lens structures may be designed to replace the converging lens 2 according to differences in application scenarios, so as to obtain higher wavefront measurement sensitivity or a larger wavefront sensing field of view. For example, in the large field of view adaptive optics technology, the lens group can be used to increase the detection field of view; or the telephoto lens structure can be used to shorten the system size.

In this embodiment, the micro-transmission mirror array 3 is a refracting micro-lens array. In other modified embodiments, other element arrays that realize the function of the micro-lens array can be used, such as reflective micro-lens arrays, and binary diffraction elements.

In other modified embodiments, an object-image conjugate system can be added between the microlens array 3 and the CCD detector 4, so as to flexibly adjust the spatial resolution of the wavefront sensing and reduce the difficulty of assembling the light field camera.

Please refer to FIG. 3 . FIG. 3 is a schematic structural diagram of data reorganization of a wavefront detection device based on a defocused light field camera. In combination with the multiple microlens units of the microlens array 3, the No. 1 pixel in the pupil image of each microlens unit is reorganized into an image according to the arrangement order of the microlens units in the microlens array 3, and the reorganized image represents The light spot on the focal plane of the light wave in a certain area at the entrance pupil is equivalent to the sub-aperture image of the Hartmann detector.

The following example is used to further illustrate the process of data reorganization, assuming that the microlens array 3 is a lens array with 300 rows and 400 columns, that is, the microlens array 3 includes 1.2w microlens units, and each microlens unit is connected to 30* 30 pixels relative setting. 30×30 sub-aperture images can be extracted, and each sub-aperture image is 300×400 pixels. For the sub-aperture images at the central angle, we extract the pixel values at the center of each microlens in order, and reassemble them in order. A 300×400 image is a sub-aperture image.

Further, we extract the pixel value of the No. 1 pixel of the microlens unit at position (0,0), that is, the pixel value of the sub-aperture image at position (0,0), and the pixel value of the microlens unit at position (0,1) The pixel value of the No. pixel is the pixel value at the position (0, 1) of the sub-aperture image, and so on in this order until the pixel values of No. 1 pixel of all the microlens units are extracted. By analogy, pixel values of the remaining pixels are extracted from all microlens units to generate sub-aperture images of the remaining pixels.

Using the centroid algorithm, the centroid offset of the incident wavefront to be measured can be calculated, and then the phase information contained in the wavefront to be measured can be recovered.

Please refer to FIG. 4 . FIG. 4 is a structural schematic diagram of calculating the defocus amount of a microlens array based on a wavefront detection method of a defocused light field camera according to the present invention. The wavefront measurement accuracy of the light field camera is generally determined by the aperture of the microlens unit in the microlens array 3 , the smaller the aperture of the microlens unit, the higher the slope measurement accuracy. However, the aperture of the microlens unit is usually on the order of hundreds of microns, and the spot area on the rear focal plane of the converging lens 2 is much smaller than the size of the microlens unit, so the light field camera cannot accurately perceive the centroid offset. Therefore, the area of the light spot is enlarged by placing the microlens array 3 behind the back focal plane of the converging lens 2 . Namely by introducing a defocusing amount, so that the spot area on the back focal plane of the converging lens 2 matches the size of the microlens unit, preferably, the aperture of the microlens unit is an integer multiple of the pixel size of the CCD detector, So that the light field camera can accurately perceive the centroid offset.

The setting principle of the defocus amount is to ensure that the spot area of the equivalent sub-aperture on the microlens array is greater than the aperture of the microlens unit, specifically can be expressed as f _defcous = r n f, where n is the CCD under a single microlens The number of pixels, f is the focal length of the microlens, and r is the number of microlens units occupied by the light spot of the equivalent sub-aperture, and the usual value range is 2-4.

In this embodiment, the defocus amount calculated according to the above method can ensure that the light spots in the equivalent sub-aperture cover multiple microlens units, and improve the measurement accuracy of the wavefront detector.

The process of adopting the present invention to recover the measured wavefront is:

(1) Input the ideal plane wave into the wavefront detector, and calculate the centroid position in each sub-aperture after recombining the equivalent sub-aperture image;

(2) Assuming that the wavefront to be measured can be fully represented by the first k-order Zernike aberrations, the first k-order Zernike aberrations are sequentially generated as the input of the wavefront detector, and the information of the spot array received by the wavefront detector is reorganized into an equivalent Aperture image, calculate the position of the centroid in each sub-aperture and the offset of the centroid relative to the plane wave entrance ΔS _kx (n)=S _kx (n)-S _0x (n), ΔS _ky (n)=S _ky (n )-S _0y (n);

(3) Arrange the centroid offsets of Zernike aberrations of each order obtained in step (2) according to the form of formula (1) to obtain the restoration matrix D.

(4) Calculate the generalized inverse matrix of the restoration matrix D to obtain the reconstruction matrix;

(5) When the wavefront to be measured with distortion is incident on the wavefront sensor of the light field camera, reorganize the CCD image according to the method in step (2) and calculate the centroid offset to obtain the vector

G＝[ΔS _x (1), ΔS _y (1), ΔS _x (2), ΔS _y (2),...ΔS _x (n), ΔS _y (n)] ^T (2)

(6) The Zernike aberration coefficients of each order included in the wavefront to be measured can be obtained by A=D ⁺ ·G.

The present invention utilizes the combination of a converging lens, a microlens array and a CCD detector to solve the defects of poor linearity and low wavefront measurement accuracy of the existing light field camera wavefront sensor by optimizing the design of the optical structure, and constructs a visual It is a wavefront sensor with large field, large dynamic range, high measurement accuracy and simple structure.

Here, the abscissa and ordinate of the following figures are analyzed and explained. The left ordinate and bottom abscissa in FIG. 5A , FIG. 6A , and FIG. 7A are used to represent the spatial coordinates of the wavefront, that is, the coordinate (0, 0) represents the center position of the wavefront. The ordinate on the right represents the Zernike polynomial coefficients. As shown in 5B, FIG. 6B and FIG. 7B, the ordinate represents the Zernike polynomial coefficients, and the abscissa represents the Zernike polynomial order.

Please refer to FIGS. 5A-5B together, wherein FIG. 5A is a schematic diagram of the input wavefront to be measured, and FIG. 5B is a Zernike polynomial coefficient of the input wavefront to be measured corresponding to FIG. 5A .

Please refer to Figures 6A-6B together, where Figure 6A is a schematic diagram of the wavefront reconstruction result of an existing light field camera, and Figure 6B is the Zernike polynomial coefficient of the wavefront reconstruction result corresponding to Figure 6A and the Zernike polynomial of the wavefront to be measured Coefficient comparison chart. The circular marks are the Zernike polynomial coefficients of the wavefront to be measured, and the rhombic marks are the Zernike polynomial coefficients of the wavefront reconstruction results. The existing light field camera is used to detect and reconstruct the wavefront, and the reconstruction result is shown in Figure 6A. As shown in Figure 6B, there is a large gap between the Zernike polynomial coefficients obtained by wavefront reconstruction with the existing light field camera and the input Zernike polynomial coefficients of the wavefront to be measured, the residual error is about 0.4λ, and its measurement accuracy is low.

Please refer to Figures 7A-7B together, where Figure 7A is a schematic diagram of the wavefront reconstruction result of a wavefront detection device based on a defocused light field camera, and Figure 7B is the Zernike polynomial coefficient of the wavefront reconstruction result corresponding to Figure 7A Comparison plot with the Zernike polynomial coefficients of the wavefront to be measured. The circle marks are the Zernike polynomial coefficients of the wavefront to be measured, and the square marks are the Zernike polynomial coefficients of the wavefront reconstruction results. As shown in Figure 7B, the Zernike polynomial coefficients obtained from the wavefront reconstruction of the out-of-focus line light-field camera are basically consistent with the input Zernike polynomial coefficients of the wavefront to be measured, and the residuals are all less than 0.005λ, indicating high measurement accuracy. That is, compared with the existing wavefront detection method, the wavefront detection method based on the defocused light field camera provided by the present invention has an obvious optimization effect in measurement accuracy.

The present invention also provides a wavefront detection method based on a defocused light field camera corresponding to the above wavefront detection device, for detecting the wavefront to be measured. In the method, the optical signal of the spot array is received by the CCD detector, and recombined to obtain an equivalent sub-aperture image, and after the centroid offset of the wavefront to be measured is calculated through the equivalent sub-aperture image, the reconstructed The matrix calculates the Zernike aberration coefficients of each order of the wavefront to be measured to obtain the phase distribution of the wavefront to be measured.

The above is a specific description of the preferred implementation of the present invention, but the invention is not limited to the described embodiments, those skilled in the art can also make various equivalent deformations or replacements without violating the spirit of the present invention , these equivalent modifications or replacements are all within the scope defined by the claims of the present application.

Claims (10)

1. A wavefront detection device of a defocused light field camera, characterized in that it comprises: A converging lens for converging the wavefront to be measured; A microlens array, configured to divide the light spot formed by converging the wavefront to be measured by the converging lens, and the microlens array includes a plurality of microlens units; The CCD detector is used to receive the light spot array information formed after the microlens array divides the light spot, and the distance between the microlens array and the CCD detector is equal to the focal length of the microlens unit; The microlens array is located at the defocus amount f _defcous with the focal distance of the converging lens _; The number of pixels of the CCD detector, f is the focal length of the microlens unit, and r represents the number of microlens units occupied by the light spot of the equivalent sub-aperture. 2 . The wavefront detection device according to claim 1 , further comprising an optical matching system, the optical matching system is arranged at the input end of the converging lens, and is used to match the wavefront to be measured to the converging lens. 3 . 3. The wavefront detection device according to claim 1, further comprising a processing module configured to reorganize the spot array information to obtain an equivalent sub-aperture image, through the equivalent sub-aperture image After calculating the centroid offset of the measured wavefront, the reconstruction matrix is used to calculate the Zernike aberration coefficients of each order of the measured wavefront to obtain the phase distribution of the measured wavefront. 4. The wavefront detecting device according to claim 3, characterized in that, Described processing module calculates each order Zernike aberration coefficient of wavefront to be measured by following algorithm: P1: Input the ideal plane wave into the wavefront detection device, calculate the centroid position S _0x , S _0y in each sub-aperture after recombining the equivalent sub-aperture image; P2: Assuming that the wavefront to be measured can be fully represented by the first k-order Zernike aberrations, the first k-order Zernike aberrations are sequentially generated as the input of the wavefront detection device, and the information of the spot array received by the wavefront detection device is reorganized into an equivalent sub-aperture Image, calculate the position of the centroid in each sub-aperture and the offset of the centroid relative to the plane wave entrance ΔS _kx (n)=S _kx (n)-S _0x (n), ΔS _ky (n)=S _ky (n) -S _0y (n); P3: arrange the centroid offsets of Zernike aberrations of each order obtained in step P2 according to the form of formula (1), and obtain the restoration matrix D ^2n×k ; P4: Calculate the generalized inverse matrix of the restoration matrix D ^2n×k to obtain the reconstruction matrix D ⁺ ; P5: When the wavefront to be measured is incident on the wavefront detection device, reorganize the spot array information into the sub-aperture image and calculate the centroid offset to obtain the vector G＝[ΔS _x (1), ΔS _y (1), ΔS _x (2), ΔS _y (2),...ΔS _x (n), ΔS _y (n)] ^T (2) P6: The Zernike aberration coefficients of each order included in the wavefront to be measured can be obtained by A=D ⁺ ·G. 5. The wavefront detecting device according to claim 1, characterized in that, the F-number of the microlens unit is smaller than the F-number of the converging lens. 6. The wavefront detection device according to claim 1, wherein the aperture of the microlens unit is an integer multiple of the pixel size of the CCD detector. 7. The wavefront detection device according to claim 1, wherein the focal lengths of each microlens unit in the microlens array are equal, the fill factor of the microlens unit is greater than 99%, and the transmittance is greater than 99%. %. 8. A wavefront detection method based on a defocused light field camera, comprising: Use a converging lens to converge the wavefront to be measured; Using a microlens array to divide the light spot formed by the converging lens to converge the wavefront to be measured to form a light spot array, the microlens array includes a plurality of microlens units; Using a CCD detector, placing the microlens array of the CCD detector at the focal plane of the microlens array to receive the spot array light signal; The defocus of described converging lens and described lens array is f _defcous =r n f, n is the pixel number of the corresponding CCD detector of a microlens unit in the microlens array, and f is the focal length of microlens unit , r represents the number of microlens units occupied by the light spot of the equivalent sub-aperture. 9. The wavefront detection method according to claim 8, further comprising: The optical signal of the spot array is received by the CCD detector, and recombined to obtain an equivalent sub-aperture image. After calculating the centroid offset of the wavefront to be measured through the equivalent sub-aperture image, the reconstruction matrix is used to calculate the The Zernike aberration coefficients of each order of the wavefront are measured to obtain the phase distribution of the wavefront to be measured. 10. The wavefront detection method according to claim 9, further comprising: Use the reconstruction matrix to calculate the Zernike aberration coefficients of each order of the wavefront to be measured to obtain the phase distribution of the wavefront to be measured, which specifically includes sub-steps: P1: Input the ideal plane wave into the defocused light field camera, and recombine to obtain the equivalent sub-aperture image, and calculate the centroid position S _0x , S _0y in each sub-aperture; P2: Assuming that the wavefront to be measured can be fully represented by the first k-order Zernike aberration, the first k-order Zernike aberration is sequentially generated as the input of the defocused light field camera, and the image received by the CCD detector is reorganized into an equivalent sub-aperture image, Calculate the centroid position in each sub-aperture and the centroid offset relative to the plane wave entry ΔS _kx (n)=S _kx (n)-S _0x (n), ΔS _ky (n)=S _ky (n)-S _0y (n); P3: Arrange the centroid offsets of Zernike aberrations of each order obtained in step (2) according to the form of formula (1), and obtain the restoration matrix D ^2n×k : P4: Calculate the generalized inverse matrix of the restoration matrix D to obtain the reconstruction matrix D ⁺ ; P5: When the wavefront to be measured is incident on the defocused light field camera, the image received by the CCD detector is reorganized into the sub-aperture image and the centroid offset is calculated to obtain the vector G＝[ΔS _x (1), ΔS _y (1), ΔS _x (2), ΔS _y (2),...ΔS _x (n), ΔS _y (n)] ^T (2); P6: The Zernike aberration coefficients of each order included in the wavefront to be measured can be obtained by A=D ⁺ ·G.