An Experimental Single Fourier Transform Optical Processor Applied to Film Grain Analysis and a Ship Wave Detection Method

摘要

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, the 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. The output light intensity was determined as a function of the filter angular position. The output intensity when considered to be periodic was found to have a discernible spectral content due to the ship wave. (Author)