Determination of modulation and background intensity by uncalibrated temporal phase stepping in a two-bucket spatially phase stepped speckle interferometer

A new phase stepping method is presented, based on the combination of spatial and temporal phase stepping. The method comprises one fixed spatial phase step of π/2 and two arbitrary, unknown temporal phase steps. The method prevents phase errors caused by phase changes during temporal phase stepping. It is therefore in particular useful for dynamic applications, but will also improve system performance for quasi-static applications in non-ideal environments.