Study On Technology Of Wavefront Sensing Based On Image Information Of Focal Plane

Along with the increasingly urgent demand for large diameter imagingtelescope, increasing the caliber of the telescope and the increase of the asphericoptical element has posed great challenges to the optical processing and testing.How to timely detect the high-order surface shape error correction, how in theprocess of the optical system with adjustable on-line detection aberration changes, inorder to adjust the primary mirror supporting plan, and the optical system withadjustable how dynamic detecting system in the process of optical system usingwave aberration to carry out fault diagnosis and the image clearer. The system ofwavefront solutions based on the focal plane image information, also known as thefocal plane detector, has some irreplaceable advantages comparing to a pupil surfacewave detector, by gathering multi-frames from a given focal aberration of shortexposure images and obtain phase information wavefront of the optical system bycalculating the wavefront, and can use Zernike polynomial fitting of each individualaberrations. The realizations of phase solver technology mainly include PhaseRetrieval (PR) and Phase Diversity (PD). Focal plane wave detector can be used inthe optical system in-line detection, namely directly measure of the transfer functionof the system of a whole system and wavefront aberration without changing theoptical system; On-orbit quantitative detection; Mosaic mirror image of confocal detection field, etc.Based on the analysis of domestic and foreign research progress, we have donea large number of simulation and the actual optical experimental work, in this paper,and have carried on the deep discussion and analysis of the principle of the PR andPD technology, performance and practical application, and on the a large number ofverification in optical detection, specific work is as follows:1. Through theoretical analysis and simulation, this paper analyzes the variousalgorithms of PR, establish and perfect the PR mathematical model. Phase retrievaltechnique is mainly studied the Gerchberg-Saxton algorithm and gradient searchalgorithm, when any amount of input images and their defocus amount as input, thispaper educes the objective function of the gradient search algorithm respectively ongeneralized pupil, wavefront and Nick coefficient of partial derivative, and revealsthe relationship between the GS algorithm with gradient search algorithm. For singleand multiple images are used as input, designs simulation experiment with GSalgorithm and gradient search algorithm, the experimental results show that for asingle image as input, the gradient search algorithm is superior to GS algorithm, formulti-frame different defocus amount of images as input, GS algorithms andgradient search algorithm can be a good solution calculated wavefront, but thegradient search algorithm convergence speed significantly better than the GSalgorithm.2. The objective function of the phase difference algorithm was modified tosolve the adaptive optics system of non-common path aberration detection ofinaccurate defocus and use the multi-channel constrained wavefront solution set andthe aberration detection with deformable mirror adjustment each iterationconvergence ultimately. The betterment method has higher accuracy in solving thewavefront theoretically.3. Build an experimental based on the PRWS method comparing with ZYGOinterferometer. This paper utilizes liquid crystal space light modulator (LC-SLM) toproduce single aberration and random aberration, and validates the ability of PRWS measurement for any aberrations. Experimental results demonstrate that agreementis obtained among the errors distribution, PV value and RMS value of ZYGOinterferometer. The measurement precision of wavefront is3/1000wavelength RMS.Therefore, the feasibility and accuracy of the proposed method can be confirmed.4. In order to verify the performance of phase retrieval wavefront sensingdemonstration system and the phase difference wavefront detector demonstrationsystem by using its own light source to complete the wavefront detection taskindependently. This paper sets up two detection mirror surface shape of experimentplatforms with the method of PRWS and PDWS, and compares both PRWSmeasurement results and PDWS measurement results with ZYGO interferometermeasurement results, experimental results demonstrate that good agreement isobtained among the errors distribution, PV value and RMS value of ZYGOinterferometer, so as to realize the estimation of large mirror aberration, whichvalidates the accuracy of PRWS and PDWS. PRWS technology and PDWStechnology can effectively estimate the aberration of spherical mirror.