Comparative analysis of absolute methods to test rotationally asymmetric surface deviation

摘要

We have provided a comparative analysis of methods that involves multi-angle averaging, pseudo multi-angle averaging, single-rotation and variants based on the combinations. All these methods require measurement results being determined at rotational positions, serving for the interferometric measurement of rotationally asymmetric surface deviation of a specimen. Zernike coefficients and power spectral density (PSD) are computed and used for detailed comparison. The experimental results show that single-rotation method gives noticeably smoother result, thus it is limited to applications of measuring low spatial frequency deviations, taking the advantage of quick measurement time with fairly accurate rms results and potentially less influence of environment; in contrast, the result with multi-angle averaging contains more information of mid and high spatial frequency but it's time-consuming. The pseudo multi-averaging method is the concise variant with fewer measurements. Its result contains more noise errors depending on the number of rotational measurements of multi-averaging method.