Research On Image Quality Detection Of Optical System With Sparse Subaperture Stitching

The wavefront aberration of optical system,which determines the imaging quality and reflects the level of optical system installation and harmonic processing,is the most important characteristic index.The image quality of optical system is usually detected by plane mirror self-collimation method.With the increase of optical system aperture,the high precision inspection needs to seek the large aperture and high precision plane mirror,so that it virtually increases the difficulty and cost.In 1980 s,the subaperture stitching,which mainly include overlap sub-aperture stitching and sparse sub-aperture stitching,was first proposed by Kim C.J of the Arizona Optical Center of the United States.It is to replace the large aperture standard plane mirror with several small sub-apertures plane mirror.When the size of the optical system is more than meter level,the overlap sub-aperture stitching needs complex mechanical mechanism,and the overlap area,in which the point-to-point accurate matching,is more than 15%,therefore it is low efficiency.Sparse sub-aperture splicing has the advantages of high efficiency,high feasibility,low cost and easy to expand,which provides an effective way.The main task of this thesis is to study the theory and key technical problems of sparse sub-aperture stitching,and to explore the sparse sub-aperture detection technology.The main contents of this thesis are as follows:(1)This paper investigates the background and significance of the subject,briefly summarizes the sub-aperture stitching detection technology and two typical sub-aperture stitching algorithms.The common methods and limitations of wavefront detection for large aperture optical systems based on sub-aperture detection are discussed.Then the sparse sub-aperture splicing detection technology is proposed and its history and technical status are investigated.Based on the analysis of its development trend and application prospect,the principle of sparse sub-aperture splicing detection technology and the composition of the experimental system are discussed,and the key problems and technical difficulties of the technique are analyzed.(2)According to the principle of sparse sub-aperture stitching,the mathematical model of the number,size and arrangement of sub-aperture is established in the unit circle.The numerical results are analyzed.For optical system below 1.5 m,the optimal arrangement of seven sub-apertures in the unit circle is selected.For the optical system with larger aperture,the cost of the sub-aperture plane mirror is taken into account.The sparse sub-aperture alignment model needs further optimization.(3)Sparse sub-aperture stitching algorithm is the final implementation of sparse sub-aperture stitching detection technology.In this paper,two typical splicing algorithms are studied: discrete phase based stitching algorithm and Zernike polynomial stitching algorithm.Finally,a splicing algorithm based on the orthogonal polynomial of sparse sub-aperture region is proposed,which constructs the orthogonal polynomial of sparse sub-aperture region.The correlation between the polynomial and the Zernike polynomial in the sampling region is analyzed,and its orthogonality is verified.Finally,the sparse sub-aperture region orthogonal polynomial is used as the base function and the matrix splicing technique is fused.The sub-aperture data splicing is processed,and the feasibility of the algorithm is verified by simulation.(4)Two verification experiments were built.4D interferometer was used to test a 150 mm plane mirror and a Φ 400 mm parallel light tube respectively.The experiments were compared with the full-aperture detection wavefront.The feasibility of the algorithm is verified,and the errors in the experiment are classified and analyzed.