Phase shifting algorithms for nonsinusoidal signals compensating nonlinear phase-shift errors and their susceptibility to random noise

In phase-shifting interferometry, nonlinear motion of the phase shifter and non-sinusoidal waveform of the signal are the two most common sources of systematic errors in the measured phase. A j + 4-sample algorithm is derived which compensates for quadratic nonlinearity of the phase shifter and the effect of harmonic components of the signal up to the jth order. The susceptibility of the algorithm to random noise is also discussed.