Vibration-induced phase errors in high-speed phase-shifting speckle-pattern interferometry

We present results from numerical simulations of a dynamic phase-shifting s peckle interferometer used in the presence of mechanical vibrations. The si mulation is based on a detailed mathematical model of the system, which is used to predict the expected frequency response of the rms measurement erro r, in the time-varying phase difference maps, as a result of vibration. The performance of different phase-shifting algorithms is studied over a range of vibrational frequencies. Phase-difference evaluation is performed by me ans of temporal phase shifting and temporal phase unwrapping. It is demonst rated that longer sampling windows and higher framing rates are preferred i n order to reduce the phase-change error that is due to vibration. A numeri cal criterion for an upper limit on the length of time window for the phase -shifting algorithm is also proposed. The numerical results are finally com pared with experimental data, acquired with a phase-shifting speckle interf erometer of 1000 frames/s. (C) 2001 Optical Society of America.