High precision optical components with large numerical aperture are widely used in industrial products. The stitching interferometry system was designed to measure high-numerical-aperture sphericity and extended the measurement range of interferometry. Firstly, sub-aperture stitching model and experimental system were analyzed. Adjustment mechanism with seven degrees of freedom was built to keep spherical surface in the null position. Then, optical path difference caused by adjustment errors was described by mathematical model. The misalignment aberrations in measurement result were removed after fitted by the Zernike polynomial and the accurate surface shape of single aperture is gained. Finally, a high-numerical-aperture sphericity was measured by the error homogenization algorithm. The PV and RMS are consistent with the results of full aperture testing.
This paper presents a method of absolutely calibrating the fabrication error of the CGH in the cylindrical interferometry system for the measurement of cylindricity error. First, a simulated experimental system is set up in ZEMAX. On one hand, the simulated experimental system has demonstrated the feasibility of the method we proposed. On the other hand, by changing the different positions of the mirror in the simulated experimental system, a misalignment aberration map, consisting of the different interferograms in different positions, is acquired. And it can be acted as a reference for the experimental adjustment in real system. Second, the mathematical polynomial, which describes the relationship between the misalignment aberrations and the possible misalignment errors, is discussed.