Accurate measurement of absolute retardation using holography.

A simple and accurate method of measurement of absolute retardation using holography is described. In this, the retardation added in the object beam between the exposure causes a shift in the fringe pattern in the reconstruction. This is achieved by rotating the direction of polarization of the beam between the exposures. The method makes use of a single view, and it has some specific advantages over the present methods in vogue. Some experimental results are presented as supporting evidence. The method is useful for the measurement of general displacements, strains, and material properties.