Research on non-null convex aspherical sub-aperture stitching detection technology

In order to realize the high-precision detection of large-caliber convex aspherical mirrors, we study the convex aspheric non-null sub-aperture stitching detection technology, and establish a set of non-null stitching detection algorithm model, in which the test errors introduced by non-null detection of the coaxial sub-aperture and the off-axis sub-aperture are modeled and analyzed. At the same time, testing error elimination, stitching coefficients calculation and full-aperture surface acquiring are also analyzed. Finally, combined with actual project, stitching detection of a convex hyperboloid with a diameter of 130 mm is performed. The non-null detection error form of each test sub-aperture of the aspheric surface is discussed, and error elimination, full-aperture surface acquiring and other work are carried out. It can be found from the stitching result that the stitching is smooth, continuous, and there is no stitching trace. To further verify the stitching accuracy, we compare the stitching result with the sub-aperture testing result. The self-test sub-aperture evaluation method is used to calculate the residual map of the self-test sub-aperture and the stitching result in the self-test sub-aperture range. The PV and RMS values of the residual map are 0.016λ and 0.003λ, respectively. From the above results, it can be concluded that the test results of the self-test sub-aperture and the stitching result are consistent within the self-test sub-aperture range, thus verifying the stitching accuracy of the algorithm.