Holographic lateral shear interferometer for differential interference contrast method

A new holographic lateral shear interferometer is described for observation of a phase object by differential interference contrast method. In this interferometer, an afocal optical system is used which is composed of two lenses with the same focal length and a pair of three-beam holograms are placed in the object plane and in the image plane. These holograms play the role of beam-splitters that divide the wavefront from a phase object into two wavefronts and shear them. To give the phase retardation of pi /2 between these sheared wavefronts, one of the holograms is moved laterally. This interferometer is easily adjustable to any amount of shear by moving a phase object placed behind the first hologram along the optical axis.