Speckle shearing interferometry using a diffractive optical beamsplitter

A novel shearing interferometer is described that uses an optimized phase grating as the shearing element. The method has a number of advantages over a conventional Michelson interferometer shearing device, including light efficiency, simplicity, and low cost. Quantitative fringe analysis is easily carried out by in-plane translation of the grating and the use of standard phase-shifting algorithms. The influence of higher diffraction orders on the noise in the measured phase distributions is discussed. (C) 1997 Society of Photo-Optical Instrumentation Engineers.