Phase-retrieval problem and orthogonal expansions: curvature sensing

An analytical solution of the curvature-sensing equation is proposed. The approach developed is based on the construction of a set of special polynomials that allows a solution in terms of Zernike polynomials by direct integration. The calculation results show that it is possible to retrieve the Zernike coefficients of wave-front distortion independently of each other by use of a few points of integration. Because the method developed requires a small number of operations, it allows the wave-front distortion of interest to be obtained in real time, which is important for adaptive-optics applications.