THEORETICAL PREDICTION OF THE EFFECT OF SHEAR DISTORTION IN THE MICHELSON INTERFEROMETER

The preferred device for effecting the image shear in shearography tod ay is the Michelson interferometer. In this paper we present a geometr ical proof of the existence of a new effect, namely, a second-order de viation of the image separation of the Michelson interferometer from a pure shear. We call it shear distortion. At present, this effect is o f purely theoretical interest. However, we refer to a newly developed shearographic technique which has the potential to substantially incre ase both the accuracy and the sensitivity of shearographic measurement s, and for which the effect of shear distortion is likely to become im portant.