Novel 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 introduced. Where high frequency intensity modulation of laser beam and phase lock-in as well as the closed loop control techniques are used. The wobble of interference fringes can be compensated, and sequentially be locked at arbitrarily chosen phases for phase-shifting testing. Comparing with other similar techniques, here the depth of signal modulation is not limited by the magnitude of optical path difference (OPD) and the fringe contrast is not reduced by the modulation, hence a high SNR can be obtained. The experimental results and conclusions are presented.