LINEAR-SYSTEMS APPROACH TO SIMULATION OF OPTICAL DIFFRACTION

The diffractive processes within an optical system can be simulated by computer to compute the diffraction-altered electric-field distributi on at the output of the system from the electric-field distribution at the input. In the paraxial approximation the system can be described by an ABCD ray matrix whose elements in turn can be used to simplify t he computation such that only a single computational step is required. We describe two rearrangements of such computations that allow the si mulation to be expressed in a linear systems formulation, in particula r using the fast-Fourier-transform algorithm. We investigate the sampl ing requirements for the kernel-modifying function or chirp that arise s. We also use the special properties of the chirp to determine the sp reading imposed by the diffraction. This knowledge can be used to redu ce the computation if only a limited region of either the input or the output is of interest. (C) 1998 Optical Society of America.