Measuring the strains of diffuse surfaces by digital speckle-interferometry

This paper describes a method of digital speckle-interferometry with controllable phase difference between the object and reference beams, in which the errors associated with speckle noise are reduced. This allows one to determine with high accuracy the phase shift caused by loading of an object. This in turn makes it possible not only to substantially enhance the accuracy with which the surface displacements and strains of a test object are determined but also to completely automate the process of determining them. (C) 1996 The Optical Society of America.