Least-squares fitting of wavefront using rational function

This paper describes a mathematical method for approximation of the measurement data in optical testing techniques. Presented method uses a least-squares fit of two-dimensional rational function model to interferometric data. It is suitable for an analytical expression of wavefront, and one can obtain sufficient accuracy with a relatively small number of approximation coefficients. Properties of the proposed method are analyzed in this work. It is shown that the technique can be used for analyzing wavefront deformation in optical testing methods.