Abstract

The sampled slope of a 2-D coherent wavefront can be measured by a relatively simple optical-digital processor based on the Fourier differentiation theorem. A linear amplitude filter is used to estimate the phase derivatives in two orthogonal directions. ¹ However, this simple version of the processor has a major shortcoming in that the processor cannot sense pi phase discontinuities. By employing an additional set of filters, the sampled derivatives of the modulus and phase can be measured. With the help of the Fletcher-Reeves conjugate gradient nonlinear optimization technique, a sampled estimate of a more general wavefront can be obtained. The principle of operation and computer simulation results are presented.

© 1989 Optical Society of America