Pointwise automatic analysis of speckle photographs.

An automatic system for analyzing specklegrams point by point is described. A new method of evaluating Young's fringes based on making a TV camera scan both horizontally and vertically is proposed. Tracking, filtering, and edge locating techniques are developed to acquire fringe data. Experiments show that Young's fringes can be determined with an accuracy of 1% in spacing and 1° in orientation, and the displacement can be found with an accuracy of 1 μm in the range 20 to 100 μm.