Development of an Automatic Analyzer of Speckle Photographs

Abstract

A micro-computer controlled electro-optical system for automatic evaluation of displacement distribution from specklegrams in double-exposure speckle photography is developed. It is capable of random addressing of a laser beam on the specklegrams by using a pair of galvanomirror deflectors and electronic scanning of the resultant Young fringes by a linear photodiode array to determine their orientation and spacing. The fringes and oriented normal to the diode array by rotating a Dove prism until the computed value of the degree of modulation in the video signal becomes maximum, and then their spacing is evaluated. Examples of the automatic evaluation are shown as a vectorial diagram of in-plane displacement.