Research On The Algorithm Testing Optical Mirror By Subaperture Stitching Interferometry

With the development of space optical technology, the aperture of the optical system is growing, causing the aperture of the optical mirrors becoming larger and larger. It usually needs auxiliary optical components such as compensator, CGH for traditional methods when testing large flat mirror, large convex sphere and asphere mirrors. It is not only difficult to process these large reference mirror and auxiliary optical components, but also time-consuming and expensive. At the same time, it will introduce some processing and alignment errors.As an effective optical testing method, subaperture stitching not only broadens the dynamic range of the interferometer but also accomplish the testing to large plane, sphere and asphere mirrors without additional components. It improves the testing resolution, reduces the cost and shortens the timescale. In this paper, we mainly studied the stitching algorithm and verified the accuracy of the algorithm based on project examples. The contents of the paper include the following four parts:1, Combined with maximum likelihood estimation and orthogonal fitting of Zernike polynomial theory, we established an algorithm model testing optical plane mirror considering that the error of the reference mirror can not be ignored. With the algorithm, both the shapes of the reference mirror and the test mirror can becalculated. Simulation is performed combined with TMT(thirty-meter telescope program) program to verify the accuracy and reliability of the algorithm.2, Subaperture arrangement and correction of projection distortion were studied when testing sphere mirrors with circular subapertures. At the meantime, a reasonable mathematical model was proposed. Subaperture arrangement, correction of projection distortion and stitching could be accomplished when we know the aperture and radius of curvature of the sphere mirror. The effectiveness of the model was also verified with engineering examples.3, We studied the theory of non-null stitching testing to asphere mirrors with circular subapertures, including the radius calculation of the best-fit sphere;subapertures arrangement; non null errors calculation; correction of projection distortion. Combined the triangulation theory and the least-squares fitting theory, an reasonable algorithm model was established and the testing accuracy of the model was calculated with engineering examples.4, we combined the stitching with other compensation technology such as compensator, CGH and established a mixed compensation testing model. The effectiveness of the model was studied with engineering examples. At the same time,we proposed a model accomplishing the alignment between processing coordinate and testing coordinate. Optical processing and testing could be carried on based on this model and the validity of the model was verified with engineering examples.