Optical correlator as a tool for physicists and engineers training in signal processing

Abstract

In many fields of Physics and Engineering the linear systems are studied. The Fourier Transform is a powerful tool for analyzing their behaviour in terms of the frequency contents, both for the input signal and the output signal. The concept of Fourier Transform is generally introduced by mathematical tools. An optical correlator is a set-up that allows to display the decomposition of a signal (1D or 2D) and the processing of this signal. In this communication we use an optical correlator with two arms that gives the display of the Fourier plane and the final plane simultaneously. In the first arm, we can visualize the decomposition of the signal in the Fourier space with the application of a given filter. The effect of the filter on the signal is observed in the second arm. The detection is performed by means of CCD cameras and displayed on the computer monitor. Binary filters help to understand the frequency contents of a signal by substraction of frequencies. Gray level filters and complex valued filters allow the synthesis of any transfer function. In particular we show the application to pattern recognition.