Abstract

A hybrid optical–digital processor employs the Fourier differentiation theorem to compute the 2-D gradient of wavefront slopes. By means of a coherent optical processor with linearly varying amplitude transmittance in the Fourier-transform plane¹ and a 2-D detector array in the output plane, an intensity image is produced which contains the derivatives of the input wavefront. Simple on-line digital computations on four images recorded in sequence with electronically switched amplitude transmittances at positions 0, 90, 180, and 270° yield the phase derivatives in orthogonal directions. Phase can be found by integrating the phase gradient.

© 1988 Optical Society of America