Digital phase-shifting shearography for slope measurement

An electronic speckle shearing interferometry method for the full field measurement of the slope of an object is presented. The abject under study is placed an a rotating platform and illuminated by an expanded laser beam. its image is recorded by a shearing CCD camera and stored directly into a computer. By recording two images before and after giving the object a small angle of rotation, the resulting correlation fringe pattern that represents the object surface slope can be obtained. The theory of the new method and some experimental results are presented. (C) 1999 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(99)01209-X].