Compensation for center offset error in annular subaperture stitching interferometry

In order to reduce the center offset error in aspheric surface testing by annular subaperture stitching interferometry, the mechanism of action of center deviation error in the surface shape measurement was analyzed, and the error model based on the testing principle and geometrical relationship was established. A compensation method for the center offset error based on two-dimensional matrices of pixel was proposed. The method is effective for searching the center offset of the initial surface shape measurement data and reducing the eliminate error of the wavefront error caused by the center offset error, and the error among the centers of annular subapertures can also be decreased. The error compensation experiment for the annular subaperture stitching interferometry was carried out with Zygo interferometer. The errors of peak to valley value and root mean square are -0.015λ and 0.003λ respectively compared with the null aspheric surface testing result. The experiment results show that the proposed method greatly reduces the surface measurement errors and improves the measurement precision of annular subaperture stitching interferometry.