A real time phase reversal read-out system with BaTiO<inf>3</inf> crystal as a recording medium for speckle fringe analysis

A real-time phase reversal speckle photography system using BaTiO 3 crystal as a recording medium is developed for phase step calibration. A π-phase shift on the random speckle pattern is accomplished by varying pressure within an air-filled quartz cell inserted in the pump beam in a two-beam coupling arrangement It is shown that phase reversal can be achieved when a π-shifted speckle pattern overlaps on an un-shifted speckle pattern at the observation plane in real-time, results in, destructive interference between the two speckle patterns. This phenomenon is exploited for calibration of the phase shifter. A four frame phase shifting technique is used, and the experimental whole field speckle fringe analysis carried out on a diffuse surface subjected to rotation in its own plane is presented.