Displacement measurement of speckles using a 2-D level-crossing technique

This paper proposes a new displacement method for measuring speckles using a 2-D level-crossing technique. The crossing points in space of the speckle intensity traversing a specified level are analyzed two-dimensionally by using a TV-computer system. In an actual analysis, an occurrence rate histogram of the distance vectors determined by connecting the crossing points obtainable before and after displacement of speckles is investigated. It is found that the vectorial displacement of speckles can be measured from the position of the maximum occurrence in the bivariate histogram with respect to the magnitude and angle by which the displacement vector is characterized. The vectorial displacement of speckles is related to the movement of an object.