Phase-extraction algorithm in laser-diode phase-shifting interferometry

A phase-shifting interferometer with a laser diode has been studied that is insensitive to the changes in laser power associated with variation in current. The tested phase is measured by six interferograms by a newly developed phase-extraction algorithm. The phase is calculated from a least-squares fit to an interferogram. The systematic phase error that is due to the variation in laser output has been numerically investigated to have a periodicity of 2pi rad compared with the experimental result for the conventional phase-extraction algorithm. Good agreement between them is shown.