WO2021068594A1 - 一种基于扩展旋转对称结构光照明的波前重建装置及方法 - Google Patents

一种基于扩展旋转对称结构光照明的波前重建装置及方法 Download PDF

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WO2021068594A1
WO2021068594A1 PCT/CN2020/102933 CN2020102933W WO2021068594A1 WO 2021068594 A1 WO2021068594 A1 WO 2021068594A1 CN 2020102933 W CN2020102933 W CN 2020102933W WO 2021068594 A1 WO2021068594 A1 WO 2021068594A1
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structured light
lens
value
current
rotationally symmetric
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PCT/CN2020/102933
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French (fr)
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白剑
赵磊
卢斌杰
周骧东
侯晶
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浙江大学
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Priority to US17/284,861 priority Critical patent/US11846558B2/en
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
    • G01M11/02—Testing optical properties
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
    • G01M11/02—Testing optical properties
    • G01M11/0207—Details of measuring devices
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01M—TESTING STATIC OR DYNAMIC BALANCE OF MACHINES OR STRUCTURES; TESTING OF STRUCTURES OR APPARATUS, NOT OTHERWISE PROVIDED FOR
    • G01M11/00—Testing of optical apparatus; Testing structures by optical methods not otherwise provided for
    • G01M11/02—Testing optical properties
    • G01M11/0242—Testing optical properties by measuring geometrical properties or aberrations
    • G01M11/0257—Testing optical properties by measuring geometrical properties or aberrations by analyzing the image formed by the object to be tested
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/10—Beam splitting or combining systems
    • G02B27/12—Beam splitting or combining systems operating by refraction only
    • G02B27/126—The splitting element being a prism or prismatic array, including systems based on total internal reflection
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/20—Filters
    • G02B5/205—Neutral density filters

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  • the invention relates to the field of optical measurement technology, and more specifically, to a wavefront reconstruction device and method based on extended rotationally symmetric structured light illumination.
  • Computational imaging is widely used to improve imaging quality, simplify imaging systems, and break through the physical limitations of optical systems and image acquisition equipment to achieve super-resolution.
  • Phase recovery as a way of realizing computational light field imaging, has been widely used since it was proposed in the 1970s because of its stable and reliable convergence effect.
  • the traditional iterative phase recovery method is based on the Fourier transform and the inverse Fourier transform iterating repeatedly between the space domain and the Fourier domain, and imposes the real amplitude limit in the Fourier domain, and imposes the space in the spatial domain. Support domain restriction. This method converges quickly in the first few iterations, but then falls into a stagnation and often converges to the local optimal solution, which makes it difficult to achieve accurate wavefront reconstruction.
  • the diffraction spots collected in the Fourier domain are often center-symmetrical, and are limited by the size of the pixel unit of the image acquisition device, and the amount of information of the collected diffraction spots is often less.
  • people have proposed a variety of improvement measures, such as sub-aperture stitching methods, based on the partial overlap between adjacent sub-apertures to increase the amount of information in the diffraction spot.
  • the sub-aperture stitching method is more complicated and easy to introduce stitching errors.
  • Another method is to add a diffractive optical element such as a random phase plate to the optical system to increase the amount of diffraction information, but the processing error of the random phase plate will reduce the accuracy of wavefront reconstruction.
  • the purpose of the present invention is to provide a wavefront reconstruction device and method based on extended rotationally symmetric structured light illumination to solve the problem of the traditional iterative phase recovery method falling into a local optimal solution, and at the same time to overcome the traditional diffractive optical element modulation process introduced Error, through the use of spatial light modulator to generate structured light, avoiding the movement error.
  • a wavefront reconstruction device based on extended rotationally symmetric structured light illumination includes: a laser (1), an attenuating mirror (2), a microscope objective lens (3), and a needle Hole (4), collimating lens (5), beam splitting prism (6), spatial light modulator (7), lens to be tested (8) and image acquisition device (9);
  • the attenuating mirror (2) is located parallel to the laser (1)
  • the microscopic objective lens (3) is located parallel to the attenuating mirror (2)
  • the pinhole (4) is located parallel to the microscopic objective lens
  • the collimating lens (5) is located parallel behind the pinhole (4) and the collimating lens ( The front focus of 5) is located at the pinhole (4)
  • the beam splitting prism (6) is located parallel to the back of the collimating lens (5)
  • the spatial light modulator (7) is located parallel to the beam splitting prism (6)
  • the lens to be measured (8) is perpendicular to the beam emitted by the laser (1) and shares a co-optical axis with the beam splitting prism (6)
  • the image acquisition device (9) is located parallel to the lens to be measured ( 8) at the back focus;
  • the lens to be tested (8) includes the object to be tested;
  • the laser (1) emits a laser beam
  • the laser beam is attenuated by the attenuating mirror (2) in turn, the collimating lens (5) is expanded into plane parallel light, the beam splitting prism (6) splits the light and the
  • the spatial light modulator (7) modulates and generates structured light; the structured light is sequentially reflected by the beam splitting prism (6) and converged by the lens to be measured (8) before reaching the image acquisition device (9), and the image
  • the collecting device (9) collects the diffraction spot containing the information of the object to be measured and the structured light.
  • the image acquisition device (9) is a CCD camera.
  • the wavelength of the laser beam emitted by the laser (1) is 632.8 nm.
  • the present invention also provides a wavefront reconstruction method based on extended rotationally symmetric structured light illumination.
  • the wavefront reconstruction method based on extended rotationally symmetric structured light illumination is implemented based on the above-mentioned wavefront reconstruction device based on extended rotationally symmetric structured light illumination.
  • the wavefront reconstruction method based on extended rotationally symmetric structured light illumination includes the following steps:
  • the step S1 includes:
  • S1.1 Determine the initial placement direction of the spatial light modulator, and obtain the light parameters and rotation parameters of the structured light generated by the spatial light modulator;
  • the light parameters of the structured light include the period and amplitude of the structured light;
  • the rotation parameters of the structured light include a single rotation angle The total number of rotations N and the current number of rotations n; among them, And N is a multiple of 4; the initial angle of the structured light The initial value of the rotation number n is 1;
  • step S1.4 If the current rotation number is greater than N/4, perform step S1.4;
  • step 2.1 If the number of changes of the direction of the spatial light modulator is equal to 3, perform step 2.1;
  • step S1.2 If the number of changes in the direction of the spatial light modulator is not equal to 3, rotate the spatial light modulator 90 degrees counterclockwise; update the current rotation number to 1, update the current structured light angle to 0°, and return to step S1.2;
  • the step S2 includes:
  • the determining the square root of the intensity of the current diffracted spot as the amplitude value of the estimated value of the spectrum surface further includes:
  • the inverse diffraction method is used to return to the space domain to obtain the estimated value of the superposition value.
  • the updating the design value of the rotationally symmetric structured light and the estimated value of the lens to be tested specifically includes:
  • O (k(N/4-1)+n+1) is the updated estimated value of the lens to be tested
  • O (k(N/4-1)+n) is the estimated value of the current lens to be tested
  • U (n)(k) is the estimated value of the superimposed value of the current iteration
  • U (n)(k-1) is the estimated value of the superimposed value of the previous iteration
  • ⁇ is a constant
  • I ill (n)(k+1) is the updated design value of the rotationally symmetric structured light.
  • the present invention has the following advantages:
  • the wavefront reconstruction device based on the extended rotation symmetry structured light illumination of the present invention uses a spatial modulator to modulate the structured light, avoiding errors caused by mechanical rotation modulation.
  • the wavefront reconstruction method of the present invention restores the wavefront and structure to be measured at the same time. Light, effectively suppress the error caused by the spatial light modulator, and realize the accurate reconstruction of the wavefront of the lens to be measured.
  • the use of structured light illumination increases the amount of information in the collected diffraction spots and improves the accuracy of the algorithm's convergence.
  • Figure 1 is a structural diagram of a wavefront reconstruction device based on extended rotationally symmetric structured light illumination of the present invention
  • Figure 2 is a flow chart of the diffraction spot collection of the present invention
  • Fig. 3 is a schematic flow chart of the wavefront phase recovery method based on extended rotationally symmetric structured light illumination of the present invention
  • Figure 4 is the original image to be restored, in which, part (a) is the amplitude image to be restored, and part (b) is the phase image to be restored;
  • Fig. 5 is a recovery diagram obtained by using the present invention, in which part (a) is a recovered amplitude chart, and part (b) is a recovered phase chart;
  • Fig. 6 is a recovery diagram obtained by using a serial transmission algorithm, in which part (a) is a recovered amplitude chart, and part (b) is a recovered phase chart.
  • a wavefront reconstruction device based on expanded rotationally symmetric structured light illumination includes a laser 1, an attenuating mirror 2, a microscope objective lens 3, a pinhole 4, a collimating lens 5, a beam splitting prism 6, and The spatial light modulator 7, the lens to be tested 8 and the image acquisition device 9, the attenuating mirror 2 is located in parallel behind the laser 1, the microscope objective lens 3 is located in parallel behind the attenuating mirror 2, and the pinhole 4 is parallel Is located behind the microscopic objective lens 3 and the pinhole 4 is located at the focal point of the microscopic objective lens 3, the collimating lens 5 is located parallel behind the pinhole 4, and the front focal point of the collimating lens 5 is located At the pinhole 4, the beam splitting prism 6 is located parallel to the back of the collimating lens 5, the spatial light modulator 7 is located parallel to the beam splitting prism 6, and the lens to be tested 8 is perpendicular to the beam emitted by the laser 1 And the light splitting co-optical axis with the dichroic prism
  • the laser 1 After the laser 1 emits a laser beam, the laser beam is sequentially attenuated by the attenuating mirror 2, the microscope objective lens 3 is amplified and converged, the collimating lens 5 is expanded into plane parallel light, and the beam splitting surface of the beam splitting prism 6
  • the upper surface splits light and the spatial light modulator 7 modulates to generate structured light; the structured light is reflected by the lower surface of the splitting surface of the beam splitting prism 6 to the lens 8 to be measured, and the lens 8 to be measured will carry information about the object to be measured
  • the structured light After being condensed, the structured light reaches the image acquisition device 9, and the image acquisition device 9 collects the diffraction spot containing the information of the object to be measured and the structured light.
  • the wavelength of the light wave emitted by the laser 1 is 632.8 nm.
  • the image acquisition device 9 is a CCD camera, which is used to acquire diffracted spot images.
  • the present invention also provides a wavefront reconstruction method based on extended rotationally symmetric structured light illumination.
  • the method includes the following steps:
  • S1 Set up the wavefront reconstruction device, and collect the diffraction spot by the image acquisition device 9. As shown in FIG. 2, collecting the diffraction spot includes the following steps:
  • S1.1 Set the initial placement direction of the spatial light modulator 7, and obtain the period and amplitude of the input phase grating structured light.
  • the light beam reaches the spatial light modulator 7 after passing through the dichroic prism 6.
  • the spatial light modulator 7 includes an input pattern. After being modulated by the spatial light modulator 7, the input phase grating structure light is obtained. Measure the structured light of the lens 8.
  • the rotation parameters of the input pattern in the spatial light modulator 7 By adjusting the period and amplitude of the input pattern in the spatial light modulator 7, the period and amplitude of the structured light can be adjusted.
  • the rotation parameters of the structured light can be adjusted .
  • the rotation parameters of structured light include single rotation angle The total number of rotations N and the number of rotations n; among them, And N is a multiple of 4; the initial angle of structured light The initial value of the rotation number n is 1.
  • phase recovery is performed on the diffracted spot collected by S1 to obtain the wavefront information of the lens to be tested. As shown in Figure 3, it specifically includes the following steps:
  • S2.4 Use the square root of the actual measured light intensity value of the angle corresponding to the current rotation number n to replace the amplitude value of the estimated value of the spectrum surface.
  • the actual measured light intensity value of the angle corresponding to the current rotation number n refers to the intensity of the diffraction spot corresponding to the current current rotation number n.
  • O (k(N/4-1)+n+1) is the updated estimated value of the lens to be tested
  • O (k(N/4-1)+n) is the estimated value of the current lens to be tested
  • U (n)(k) is the estimated value of the superimposed value of the current iteration
  • U (n)(k-1) is the estimated value of the superimposed value of the previous iteration
  • ⁇ is a constant
  • I ill (n)(k+1) is the updated design value of the rotationally symmetric structured light.
  • the estimated value of the superposition value of the current iteration is obtained by returning to the spatial domain using the inverse diffraction method.
  • the present invention uses a spatial light modulator to modulate the incident parallel light into a structured light similar to a phase grating.
  • the pixel unit of the spatial light modulator is not infinitely small, so that it can generate different Structured light, by collecting diffracted spots on the focal plane, using algorithms to update the target surface and structured light surface at the same time, not only restores the target to be measured, but also restores the true structured light wavefront, which overcomes the problem of inaccurately known structured light information.
  • Recovery error The invention can realize the high-steep wavefront phase recovery, and does not need to move the image acquisition device, and avoids the rotation error caused by the traditional rotating illumination by introducing the spatial light modulator.
  • the wavefront reconstruction method based on rotationally symmetric structured light illumination can achieve 100% restoration of the wavefront, which overcomes the shortcomings of traditional iterative methods that are easy to converge to a local optimal solution.
  • the wavefront reconstruction method based on the rotation-expanded symmetrical structured light illumination of the present invention can overcome the restoration error caused by the actual unideal illumination light, taking the restoration of the lena and cameraman diagrams as an example, as shown in FIG. Comparing the restoration of the rotating structured light illumination with the traditional multi-image iterative phase restoration method, the restoration results are shown in Figure 5 and Figure 6. It can be seen from the figure that the recovery effect of the method of the present invention is significantly better than the traditional multi-image iterative phase recovery method.

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Abstract

一种基于扩展旋转对称结构光照明的波前重建装置，该装置包括依次设置的激光器（1）、衰减镜（2）、显微物镜（3）、针孔（4）、准直透镜（5）、分光棱镜（6）、空间光调制器（7）、待测透镜（8）、图像采集装置（9）。还提供了一种基于扩展旋转对称结构光照明的波前重建方法，其利用空间光调制器将入射的平行光调制为类相位光栅的结构光，通过改变空间光调制器的调制图案、利用空间光调制器的像素单元不是无限小的特性，使之生成不同的结构光，通过在焦平面采集衍射光斑，利用算法同时更新目标面与结构光面，不仅恢复出待测目标，也恢复出真实的结构光波前，克服由于未精确已知结构光信息带来的恢复误差。

Description

一种基于扩展旋转对称结构光照明的波前重建装置及方法
本申请要求于2019年10月10日提交中国专利局、申请号为201910959034.6、发明名称为“一种基于扩展旋转对称结构光照明的波前重建装置及方法”的中国专利申请的优先权，其全部内容通过引用结合在本申请中。
技术领域
本发明涉及光学测量技术领域，更确切的说是一种基于扩展旋转对称结构光照明的波前重建装置及方法。
背景技术
计算成像被广泛应用于提高成像质量，简化成像系统，突破光学系统与图像采集设备的物理限制实现超分辨等。相位恢复作为一种实现计算光场成像的一种方式，自上世纪70年代被提出后，由于其稳定可靠的收敛效果被广泛应用。上世纪九十年代美国罗切斯特大学将相位恢复方法成功应用于哈勃望远镜的像差矫正中。传统的迭代相位恢复方法是基于傅里叶变换和逆傅里叶变换在空间域和傅里叶域之间反复迭代，并在傅里叶域中施加真实振幅的限制，在空间域中施加空间支持域限制。此方法在前几次迭代中会快速收敛但随后陷入停滞最后往往收敛于局部最优解中，难以实现波前的精确重建。
为了改善此问题，人们做了大量的研究。在傅里叶域采集的衍射光斑往往是中心对称的，并且受限于图像采集装置像素单元的大小，采集的衍射光斑的信息量往往较少。为此人们提出了多种多样的改善措施，如子孔径拼接方法，基于相邻子孔径间部分重叠以增加衍射光斑的信息量。子孔径拼接方法较为复杂而且容易引入拼接误差。另外一种方法是在光学系统中加入衍射光学元件如随机相位板等提高衍射信息量，但是随机相位板的加工误差会降低波前重建精度。
发明内容
本发明的目的是提供一种基于扩展旋转对称结构光照明的波前重建 装置及方法，以解决传统迭代相位恢复方法陷入局部最优解的问题，同时克服了传统衍射光学元件调制过程中引入的误差，通过使用空间光调制器产生结构光，规避了移动误差。
本发明的技术方案如下：
一种基于扩展旋转对称结构光照明的波前重建装置，所述基于扩展旋转对称结构光照明的波前重建装置包括：激光器(1)、衰减镜(2)、显微物镜(3)、针孔(4)、准直透镜(5)、分光棱镜(6)、空间光调制器(7)、待测透镜(8)和图像采集装置(9)；
所述衰减镜(2)平行位于所述激光器(1)之后，所述显微物镜(3)平行位于所述衰减镜(2)之后，所述针孔(4)平行位于所述显微物镜(3)之后且所述针孔(4)位于所述显微物镜(3)的焦点处，所述准直透镜(5)平行位于所述针孔(4)之后且所述准直透镜(5)的前焦点位于所述针孔(4)处，所述分光棱镜(6)平行位于所述准直透镜(5)之后，所述空间光调制器(7)平行位于分光棱镜(6)之后，所述待测透镜(8)垂直于所述激光器(1)出射光束且与所述分光棱镜(6)分光共光轴，所述图像采集装置(9)平行位于所述待测透镜(8)的后焦点处；所述待测透镜(8)包括待测物；
所述激光器(1)发出激光光束，所述激光光束依次经所述衰减镜(2)衰减、所述准直透镜(5)扩为面平行光、所述分光棱镜(6)分光和所述空间光调制器(7)调制生成结构光；所述结构光依次经所述分光棱镜(6)反射和所述待测透镜(8)会聚后到达所述图像采集装置(9)，所述图像采集装置(9)采集含有待测物和结构光信息的衍射光斑。
可选的，所述图像采集装置(9)为CCD相机。
可选的，所述激光器(1)发出的激光光束的波长为632.8nm。
本发明还提供一种基于扩展旋转对称结构光照明的波前重建方法，所述基于扩展旋转对称结构光照明的波前重建方法基于上述的基于扩展旋转对称结构光照明的波前重建装置实现，所述基于扩展旋转对称结构光照明的波前重建方法包括以下步骤：
S1：搭建所述基于扩展旋转对称结构光照明的波前重建装置，由图像采集装置(9)采集衍射光斑；
S2：采用基于扩展旋转对称结构光照明的相位恢复方法，对所述图像采集装置采集的衍射光斑进行相位恢复，获得待测透镜的波前信息；
所述步骤S1包括：
S1.1：确定空间光调制器的初始放置方向，获取所述空间光调制器生成的结构光的光参数和旋转参数；所述结构光的光参数包括所述结构光的周期和振幅；所述结构光的旋转参数包括单次旋转角度
Figure PCTCN2020102933-appb-000001
总旋转次数N和当前旋转数n；其中，
Figure PCTCN2020102933-appb-000002
且N为4的倍数；所述结构光的初始角度
Figure PCTCN2020102933-appb-000003
所述旋转数n的初始值为1；
S1.2：采集衍射光斑；
S1.3：判断当前旋转数是否大于N/4；
若当前旋转数大于N/4，执行步骤S1.4；
若当前旋转数不大于N/4，按照所述单次旋转角度
Figure PCTCN2020102933-appb-000004
旋转所述结构光，更新当前旋转数为n+1，更新当前所述结构光的角度为
Figure PCTCN2020102933-appb-000005
Figure PCTCN2020102933-appb-000006
为前一次旋转数对应的结构光的角度；返回步骤S1.2；
S1.4：判断所述空间光调制器的方向改变次数是否等于3；
若所述空间光调制器的方向改变次数等于3，执行步骤2.1；
若所述空间光调制器的方向改变次数不等于3，将空间光调制器逆时针旋转90度；更新当前旋转数为1，更新当前结构光的角度为0°，返回步骤S1.2；
所述步骤S2包括：
S2.1：依次输入所述图像采集装置采集的N幅衍射光斑，获取待测透镜的参数、所述结构光的旋转参数和迭代总数；所述待测透镜的参数包括所述待测透镜的焦距和口径，所述结构光的旋转参数包括单次旋转角度
Figure PCTCN2020102933-appb-000007
和当前旋转数n；当前旋转数的初值为1，迭代次数k的初值为1，迭代总数为N_iter；
S2.2：获取当前旋转对称结构光的设计值和当前待测透镜的估计值；若k＝1且n＝1，将结构光的设计值初值确定为所述当前旋转对称结构光的设计值；将待测透镜的初值确定为所述当前待测透镜的估计值；若k＝1且n≠1，将结构光的角度为
Figure PCTCN2020102933-appb-000008
时的设计值确定为所述当前旋转对称结构光的设计值；将待测透镜的初值确定为所述当前待测透镜的估计值；若 k＞1，将前一次迭代中更新后的旋转对称结构光的设计值确定为当前旋转对称结构光的设计值，将前一次迭代中更新后的待测透镜的估计值确定为当前待测透镜的估计值；
S2.3：将所述当前旋转对称结构光的设计值和所述当前待测透镜的估计值叠加，得到叠加值；采用计算衍射方法将所述叠加值计算衍射至频谱面，得到频谱面估计值；
S2.4：将当前衍射光斑的强度的平方根，确定为所述频谱面估计值的振幅值；当前衍射光斑为当前旋转数n对应的衍射光斑；
S2.5：更新旋转对称结构光的设计值和待测透镜的估计值；
S2.6：令n＝n+1；若n≤N/4，返回步骤S2.2；若n＞N/4，执行步骤2.7；
S2.7：令k＝k+1；若k≤N_iter，返回步骤S2.2；若k＞N_iter，迭代结束，将当前迭代更新的待测透镜的估计值确定为最终待测透镜的波前。
可选的，所述将当前衍射光斑的强度的平方根，确定为所述频谱面估计值的振幅值，之后还包括：
采用逆衍射方法返回到空间域，得到所述叠加值的估计值。
可选的，所述更新旋转对称结构光的设计值和待测透镜的估计值，具体包括：
根据所述叠加值的估计值更新所述待测透镜的估计值，公式为：
Figure PCTCN2020102933-appb-000009
根据所述叠加值的估计值更新旋转对称结构光的设计值，公式为：
Figure PCTCN2020102933-appb-000010
其中，O (k(N/4-1)+n+1)为更新后的待测透镜的估计值，O (k(N/4-1)+n)为当前待测透镜的估计值，U (n)(k)为当前迭代的叠加值的估计值，U (n)(k-1)为前一次迭代的叠加值的估计值，α为常数，
Figure PCTCN2020102933-appb-000011
为当前旋转对称结构光的设计值，I ill (n)(k+1)为更新后的转对称结构光的设计值。
本发明与现有技术相比，其优点是：
本发明的基于扩展旋转对称结构光照明的波前重建装置，利用空间调制器调制结构光，规避了机械旋转调制带来的误差，本发明的波前重建方法通过同时恢复待测波前和结构光，有效抑制空间光调制器带来的误差，实现待测透镜波前的精确重建。使用结构光照明，增加了采集的衍射光斑中的信息量，提高了算法的收敛精度。
说明书附图
下面结合附图对本发明作进一步说明：
图1为本发明基于扩展旋转对称结构光照明的波前重建装置的结构图；
图2为本发明衍射光斑采集流程图；
图3为本发明基于扩展旋转对称结构光照明的波前相位恢复方法的流程示意图；
图4为待恢复原图，其中，(a)部分为待恢复的振幅图，(b)部分为待恢复的相位图；
图5为使用本发明得到的恢复图，其中，(a)部分为恢复的振幅图，(b)部分为恢复的相位图；
图6为使用串行传输算法得到的恢复图，其中，(a)部分为恢复的振幅图，(b)部分为恢复的相位图。
图中标号：1-激光器、2-衰减镜、3-显微物镜、4-针孔、5-准直透镜、6-分光棱镜、7-空间光调制器、8-待测透镜、9-图像采集装置。
具体实施方式
下面结合本发明实施例中的附图，对本发明实施例中技术方案进行详细的描述，显然，所描述的实施例仅是本发明一部分实施例，而不是全部的实施例；基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例都属于本发明保护的范围。
如图1所示，一种基于扩展旋转对称结构光照明的波前重建装置，包括依次设置的激光器1、衰减镜2、显微物镜3、针孔4、准直透镜5、分光棱镜6、空间光调制器7、待测透镜8和图像采集装置9，所述衰减镜2 平行位于所述激光器1之后，所述显微物镜3平行位于所述衰减镜2之后，所述针孔4平行位于所述显微物镜3之后且所述针孔4位于所述显微物镜3的焦点处，所述准直透镜5平行位于所述针孔4之后且所述准直透镜5的前焦点位于所述针孔4处，所述分光棱镜6平行位于所述准直透镜5之后，所述空间光调制器7平行位于分光棱镜6之后，所述待测透镜8垂直于所述激光器1出射光束且与所述分光棱镜6分光共光轴，所述图像采集装置9平行位于所述待测透镜8的后焦点处，所述待测透镜8包括待测物。
所述激光器1发出激光光束后，所述激光光束依次经所述衰减镜2衰减、所述显微物镜3放大会聚、所述准直透镜5扩为面平行光、所述分光棱镜6分光面上表面分光和所述空间光调制器7调制生成结构光；所述结构光经所述分光棱镜6分光面下表面反射至待测透镜8，所述待测透镜8将带有待测物信息的结构光会聚后到达所述图像采集装置9，所述图像采集装置9采集含有待测物和结构光信息的衍射光斑。
作为其中一种实施方式，所述激光器1发出的光波波长为632.8nm。
作为其中一种实施方式，所述图像采集装置9为CCD相机，用于采集衍射光斑图像。
基于上述的基于扩展旋转对称结构光照明的波前重建装置，本发明还提供一种基于扩展旋转对称结构光照明的波前重建方法，该方法包括以下步骤：
S1：搭建所述波前重建装置，由图像采集装置9采集衍射光斑，如图2所示，采集衍射光斑包括以下步骤：
S1.1：设置空间光调制器7的初始放置方向，获取输入类相位光栅结构光的周期和振幅。光束经过分光棱镜6后到达空间光调制器7，空间光调制器7包括输入图案，经空间光调制器7调制后得到输入类相位光栅结构光，即前述提到经分光棱镜6反射后到达待测透镜8的结构光。通过调节空间光调制器7中输入图案的周期和振幅，便可以调节结构光的周期和振幅，同样的，通过调节空间光调制器7中输入图案的旋转参数，便可以调节结构光的旋转参数。结构光的旋转参数包括单次旋转角度
Figure PCTCN2020102933-appb-000012
总旋转次数N和旋转数n；其中，
Figure PCTCN2020102933-appb-000013
且N为4的倍数；结构光的初 始角度
Figure PCTCN2020102933-appb-000014
旋转数n的初始值为1。
S1.2：采集衍射光斑。
S1.3：判断n是否大于N/4。若是，则执行步骤S1.4；若否，令n＝n+1，
Figure PCTCN2020102933-appb-000015
按照单次旋转角度
Figure PCTCN2020102933-appb-000016
旋转所述结构光，返回S1.2，采集旋转后的衍射光斑。
S1.4：判断空间光调制器方向改变次数是否等于3。若是，则执行步骤S2；否则，空间光调制器逆时针旋转90度，初始化旋转数和初始角度，令n＝1，
Figure PCTCN2020102933-appb-000017
返回步骤S1.2。
S2：采用基于扩展旋转对称结构光照明的相位恢复方法，对S1采集到的衍射光斑进行相位恢复，获得待测透镜的波前信息。如图3所示，具体包括以下步骤：
S2.1：输入图像采集装置9采集的N幅衍射光斑，获取待测透镜8的焦距f和口径D，获取输入类相位光栅结构光的单次旋转角度
Figure PCTCN2020102933-appb-000018
在0～90°内旋转数n，初始角度
Figure PCTCN2020102933-appb-000019
初始旋转数n＝1，迭代总数N_iter，初始迭代次数k＝1。
S2.2：获取当前旋转对称结构光的设计值和当前待测透镜的估计值。若k＝1且n＝1，将结构光的设计值初值确定为所述当前旋转对称结构光的设计值；将待测透镜的初值确定为所述当前待测透镜的估计值；若k＝1且n≠1，将结构光的角度为
Figure PCTCN2020102933-appb-000020
时的设计值确定为所述当前旋转对称结构光的设计值；将待测透镜的初值确定为所述当前待测透镜的估计值；若k＞1，将前一次迭代中更新后的旋转对称结构光的设计值确定为当前旋转对称结构光的设计值，将前一次迭代中更新后的待测透镜的估计值确定为当前待测透镜的估计值。
S2.3：将所述当前旋转对称结构光的设计值和所述当前待测透镜的估计值叠加，得到叠加值；采用计算衍射方法将所述叠加值计算衍射至频谱面，得到频谱面估计值。
S2.4：使用当前旋转数n对应角度实际测量光强值的平方根取代所述频谱面估计值的振幅值。当前旋转数n对应角度实际测量光强值是指当前当前旋转数n对应的衍射光斑的强度。
S2.5：同时更新旋转对称结构光设计值
Figure PCTCN2020102933-appb-000021
以及待测透镜估计值 O (k(N/4-1)+i)。更新公式为：
Figure PCTCN2020102933-appb-000022
Figure PCTCN2020102933-appb-000023
其中，O (k(N/4-1)+n+1)为更新后的待测透镜的估计值，O (k(N/4-1)+n)为当前待测透镜的估计值，U (n)(k)为当前迭代的叠加值的估计值，U (n)(k-1)为前一次迭代的叠加值的估计值，α为常数，
Figure PCTCN2020102933-appb-000024
为当前旋转对称结构光的设计值，I ill (n)(k+1)为更新后的转对称结构光的设计值。
当前迭代的叠加值的估计值采用逆衍射方法返回到空间域得到。
S2.6：将更新旋转对称结构光设计值
Figure PCTCN2020102933-appb-000025
确定为将此角度下的结构光逆时针旋转90度后的旋转对称结构光的设计值；
S2.7：令i＝i+1，如果i≤N/4，则返回S2.2，否则执行步骤S2.8；
S2.8：令k＝k+1，如果k≤N_iter，则返回S2.2，否则结束迭代，输出待测透镜估计值作为最终的待测透镜的波前。
本发明利用空间光调制器将入射的平行光调制为类相位光栅的结构光，通过改变空间光调制器的调制图案、利用空间光调制器的像素单元不是无限小的特性，使之生成不同的结构光，通过在焦平面采集衍射光斑，利用算法同时更新目标面与结构光面，不仅恢复出待测目标，也恢复出真实的结构光波前，克服由于未精确已知结构光信息带来的恢复误差。本发明能够实现高陡度波前相位恢复，而且不需要移动图像采集装置，通过引入空间光调制器规避了传统旋转照明带来的旋转误差。
在理想情况下，基于旋转对称结构光照明的波前重建方法能够实现波前的100％的恢复，克服了传统迭代方法易于收敛至局部最优解的弊端。本发明的基于旋转扩展对称结构光照明的波前重建方法能够克服实际不理想照明光带来的恢复误差，以恢复lena与cameraman图为例，如图4所示。将旋转结构光照明与传统多图迭代相位恢复方法恢复对比，恢复结果如图5和图6所示。从图中可以看出，本发明的方法恢复效果明显优于 传统多图迭代相位恢复方法。
上面结合附图对本发明的实施方式作了详细说明，但是本发明并不限于上述实施方式，在所属技术领域普通技术人员所具备的知识范围内，还可以在不脱离本发明宗旨的前提下做出各种变化。

Claims (6)

  1. 一种基于扩展旋转对称结构光照明的波前重建装置，其特征在于，所述基于扩展旋转对称结构光照明的波前重建装置包括：激光器(1)、衰减镜(2)、显微物镜(3)、针孔(4)、准直透镜(5)、分光棱镜(6)、空间光调制器(7)、待测透镜(8)和图像采集装置(9)；
    所述衰减镜(2)平行位于所述激光器(1)之后，所述显微物镜(3)平行位于所述衰减镜(2)之后，所述针孔(4)平行位于所述显微物镜(3)之后且所述针孔(4)位于所述显微物镜(3)的焦点处，所述准直透镜(5)平行位于所述针孔(4)之后且所述准直透镜(5)的前焦点位于所述针孔(4)处，所述分光棱镜(6)平行位于所述准直透镜(5)之后，所述空间光调制器(7)平行位于分光棱镜(6)之后，所述待测透镜(8)垂直于所述激光器(1)出射光束且与所述分光棱镜(6)分光共光轴，所述图像采集装置(9)平行位于所述待测透镜(8)的后焦点处；所述待测透镜(8)包括待测物；
    所述激光器(1)发出激光光束，所述激光光束依次经所述衰减镜(2)衰减、所述准直透镜(5)扩为面平行光、所述分光棱镜(6)分光和所述空间光调制器(7)调制生成结构光；所述结构光依次经所述分光棱镜(6)反射和所述待测透镜(8)会聚后到达所述图像采集装置(9)，所述图像采集装置(9)采集含有待测物和结构光信息的衍射光斑。
  2. 根据权利要求1所述的基于扩展旋转对称结构光照明的波前重建装置，其特征在于，所述图像采集装置(9)为CCD相机。
  3. 根据权利要求1所述的基于扩展旋转对称结构光照明的波前重建装置，其特征在于，所述激光器(1)发出的激光光束的波长为632.8nm。
  4. 一种基于扩展旋转对称结构光照明的波前重建方法，其特征在于，所述基于扩展旋转对称结构光照明的波前重建方法基于权利要求1-3任一项所述的基于扩展旋转对称结构光照明的波前重建装置实现，所述基于扩展旋转对称结构光照明的波前重建方法包括以下步骤：
    S1：搭建所述基于扩展旋转对称结构光照明的波前重建装置，由图像采集装置(9)采集衍射光斑；
    S2：采用基于扩展旋转对称结构光照明的相位恢复方法，对所述图像采集装置采集的衍射光斑进行相位恢复，获得待测透镜的波前信息；
    所述步骤S1包括：
    S1.1：确定空间光调制器的初始放置方向，获取所述空间光调制器生成的结构光的光参数和旋转参数；所述结构光的光参数包括所述结构光的周期和振幅；所述结构光的旋转参数包括单次旋转角度
    Figure PCTCN2020102933-appb-100001
    总旋转次数N和当前旋转数n；其中，
    Figure PCTCN2020102933-appb-100002
    且N为4的倍数；所述结构光的初始角度
    Figure PCTCN2020102933-appb-100003
    所述旋转数n的初始值为1；
    S1.2：采集衍射光斑；
    S1.3：判断当前旋转数是否大于N/4；
    若当前旋转数大于N/4，执行步骤S1.4；
    若当前旋转数不大于N/4，按照所述单次旋转角度
    Figure PCTCN2020102933-appb-100004
    旋转所述结构光，更新当前旋转数为n+1，更新当前所述结构光的角度为
    Figure PCTCN2020102933-appb-100005
    Figure PCTCN2020102933-appb-100006
    为前一次旋转数对应的结构光的角度；返回步骤S1.2；
    S1.4：判断所述空间光调制器的方向改变次数是否等于3；
    若所述空间光调制器的方向改变次数等于3，执行步骤2.1；
    若所述空间光调制器的方向改变次数不等于3，将空间光调制器逆时针旋转90度；更新当前旋转数为1，更新当前结构光的角度为0°，返回步骤S1.2；
    所述步骤S2包括：
    S2.1：依次输入所述图像采集装置采集的N幅衍射光斑，获取待测透镜的参数、所述结构光的旋转参数和迭代总数；所述待测透镜的参数包括所述待测透镜的焦距和口径，所述结构光的旋转参数包括单次旋转角度
    Figure PCTCN2020102933-appb-100007
    和当前旋转数n；当前旋转数的初值为1，迭代次数k的初值为1，迭代总数为N_iter；
    S2.2：获取当前旋转对称结构光的设计值和当前待测透镜的估计值；若k＝1且n＝1，将结构光的设计值初值确定为所述当前旋转对称结构光的设计值；将待测透镜的初值确定为所述当前待测透镜的估计值；若k＝1且n≠1，将结构光的角度为
    Figure PCTCN2020102933-appb-100008
    时的设计值确定为所述当前旋转对称结构光的设计值；将待测透镜的初值确定为所述当前待测透镜的估计值；若k＞1，将前一次迭代中更新后的旋转对称结构光的设计值确定为当前旋转对称结构光的设计值，将前一次迭代中更新后的待测透镜的估计值确定 为当前待测透镜的估计值；
    S2.3：将所述当前旋转对称结构光的设计值和所述当前待测透镜的估计值叠加，得到叠加值；采用计算衍射方法将所述叠加值计算衍射至频谱面，得到频谱面估计值；
    S2.4：将当前衍射光斑的强度的平方根，确定为所述频谱面估计值的振幅值；当前衍射光斑为当前旋转数n对应的衍射光斑；
    S2.5：更新旋转对称结构光的设计值和待测透镜的估计值；
    S2.6：令n＝n+1；若n≤N/4，返回步骤S2.2；若n＞N/4，执行步骤2.7；
    S2.7：令k＝k+1；若k≤N_iter，返回步骤S2.2；若k＞N_iter，迭代结束，将当前迭代更新的待测透镜的估计值确定为最终待测透镜的波前。
  5. 根据权利要求4所述的基于扩展旋转对称结构光照明的波前重建方法，其特征在于，所述将当前衍射光斑的强度的平方根，确定为所述频谱面估计值的振幅值，之后还包括：
    采用逆衍射方法返回到空间域，得到所述叠加值的估计值。
  6. 根据权利要求5所述的基于扩展旋转对称结构光照明的波前重建方法，其特征在于，所述更新旋转对称结构光的设计值和待测透镜的估计值，具体包括：
    根据所述叠加值的估计值更新所述待测透镜的估计值，公式为：
    Figure PCTCN2020102933-appb-100009
    根据所述叠加值的估计值更新旋转对称结构光的设计值，公式为：
    Figure PCTCN2020102933-appb-100010
    其中，O (k(N/4-1)+n+1)为更新后的待测透镜的估计值，O (k(N/4-1)+n)为当前待测透镜的估计值，U (n)(k)为当前迭代的叠加值的估计值，U (n)(k-1)为前一次迭代的叠加值的估计值，α为常数，
    Figure PCTCN2020102933-appb-100011
    为当前旋转对称结构光的设计值， I ill (n)(k+1)为更新后的转对称结构光的设计值。
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