INTEGRAL EVALUATION OF THE MODAL PHASE COEFFICIENTS IN CURVATURE SENSING - ALBRECHTS CUBATURES

The modal coefficients describing a given wave front as a linear combi nation of a set of orthogonal functions can be determined independentl y of each other by a suitable integration of the signal provided by a curvature sensor. This fact allows us to avoid the use of matrix inver sion routines and overcomes some problems related to the modeling erro r arising in conventional modal fits. Several procedures for evaluatin g these integrals from a discrete set of intensity measurements are co mpared. The results show that, for a given number of sampling points, the combination of an Albrecht's cubature in the inner pupil region wi th a composite trapezoidal integration of the edge signal can give mor e accurate results with smaller noise propagators than other methods a lso analyzed. (C) 1996 Optical Society of America.