Shearing interferometry of diffusely reflecting objects

Holographic interferometry is usually too sensitive for investigating deformations of diffusely reflecting objects and there are practically no methods for controlling the sensitivity. The present paper uses the principles of the "speckle" interferometry to extend the shearing method to diffusely reflecting objects. This method can be used to measure small relative strains in the presence of large absolute deformations. In the case of phase objects the proposed method considerably simplifies the experimental procedure. The theory of the method and experimental results are described. Promising applications of the method in coherent optics are pointed out.