An experimental single Fourier transform optical processor applied to film grain analysis and a ship wave detection method

Abstract

A single Fourier transform optical system was constructed and tested on two projects. First, film grain in a single Fourier transform operation was studied and a mathematical model of the film grain and a semi-quantitative prediction of the grain's transform were developed and verified using the experimental system. The film grain was found to have a noise-like spatial frequency spectrum which was a decreasing function of frequency, and that this spectrum could be considered Gaussian only in the case of fine grain films containing binary signal images. Second, a system was used to investigate a proposed method of detecting a ship wave. A deterministic relation between a ship wave and the Fourier transform of its photograph was shown to exist. A sample photograph of a ship wave was inserted into the system and operated on by a matched filter rotated In a plane normal to the optical axis.