High precision strain measurements using speckle statistical interferometry

Abstract

A novel inteferometric method named as ‘statistical interferometry’ is described. In the method, in contrast to the conventional deterministic interferometry, the complete randomness of the interfering two light fields, i. e., therandom interference of the fully developed speckle fields, plays an essential role and is used as a standard of phase in a statistical sense. Some experiments of in-plane strain of object were conducted to demonstrate the validity of the method. As an experimental result, the accuracy of the measurements of strain was estimated to 10-7 strain with the spatial resolution <100μm. The method has the advantages of simplicity of the optical system required and at the same time providing high accuracy.