Optical surface error analysis and compensation technique based on Zernike polynomial coefficients

Abstract

Ultra-precision turning technology is widely used in the machining process of optical mirrors. Due to the influence of machine motion error, clamping error, tracking error and other factors, ultra-precision turning often deviates from the ideal position during the actual machining process. Various error factors are coupled with each other, and it is difficult to compensate by establishing an accurate error model at present. This paper proposes an optical surface error compensation method based on zernike polynomials. Firstly, the surface error is reconstructed with Zernike polynomials. Then, by analyzing the frequency distribution of the optical surface error, the error corresponding to a specific Zenick coefficient is selected. Finally, based on the fast tool servo system, the original machining path is corrected according to the error compensation strategy. By compensating a Φ100 mm mirror, the surface accuracy is improved from PV 1.83 μm, RMS 0.47 μm to PV 0.38 μm, RMS 0.04 μm. The experimental results show that the error compensation strategy proposed in this paper can significantly reduce the optical surface error and improve the machining accuracy.