Chopping adaptive phase-shifting interferometry

An adaptive phase-shifting interferometry, insensitive to the disturbance of constant term of phase perturbations induced by environmental vibration and air turbulence is discussed. Where the polarization characteristic and high frequency intensity modulation of laser beam and phase lock-in as well as the closed loop control techniques are used, and a chopping adaptive phase-shifting interference system was set up. The wobble of interference fringes can be compensated, and sequentially be locked at arbitrarily chosen phase for phase-shifting testing. Compared with other similar techniques, here the depth of signal modulation is not limited by the magnitude of optical path difference and the fringe contrast is not reduced by the modulation, hence a high signal-to-noise can be obtained. The principle and structure of the chopping adaptive phase-shifting interferometer are described. The experimental results and conclusions are presented.