Hitherto, phase-shifting schemes in wave-front interferometry required
a minimum of two precise phase steps in order to derive the phase. Th
is paper outlines and demonstrates a novel technique entailing one pre
cise phase step. Numerical analyses of phase-drift errors indicate tha
t the proposed technique compares favourably with performances of the
three- and four-bucket algorithms currently in use. Furthermore, it mi
nimizes the period of computation by necessitating the use of three pr
ocessing frames.