Double-exposure holographic interferometry using common-path reference waves

A variation of double-exposure holographic interferometry is presented that permits accurate analysis of the interferogram. This is accomplished by the use of two unique optical components: a reference wave generator that produces two common-path, orthogonally polarized, diffuse reference waves and an optical phase shifter that varies the relative phase of the reconstructed images in small, equal increments. The incorporation of these components into a typical holographic arrangement is described both experimentally and analytically. Analysis of the interferogram, including data acquisition, computation, and graphic display, is given. This technique is demonstrated for optical and nondestructive testing. Determination of the accuracy is also presented.