Portable inspection of precision surfaces by phase-shifting interferometry with automatic suppression of phase-shift errors
One important issue in phase-shifting interferometry is to eliminate phase-shift errors so as to enhance achievable measurement accuracy. We propose a new phase-measuring algorithm that can identify the actual amounts of phase shifts directly from interferograms without prior calibration. This is named the A-bucket algorithm and has the advantage of being inherently free from any phase-shift error that is constant across an interferogram. The main emphasis of this paper is given to a practicable application of the A-bucket algorithm to prove that accurate measurement is allowed in portable mode even in the presence of vibration.