SPECKLE SHEARING INTERFEROMETRY USING A DIFFRACTIVE OPTICAL BEAMSPLITTER

A novel shearing interferometer is described that uses an optimized ph ase grating as the shearing element. The method has a number of advant ages over a conventional Michelson interferometer shearing device, inc luding 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 h igher diffraction orders on the noise in the measured phase distributi ons is discussed. (C) 1997 Society of Photo-Optical Instrumentation En gineers.