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Phase shifting interferometry: reference phase error reduction

: Schwider, J.

Applied optics 28 (1989), No.18, pp.3889-92
ISSN: 0003-6935
ISSN: 1539-4522
ISSN: 1559-128X
Journal Article
Fraunhofer HHI ()
light interferometry; measurement errors; reference phase error reduction; accuracy; phase shifting interferometry; nonlinearities; phase shifter movements; calibration errors; phase drifts; low frequency mechanical vibrations; sinusoidal fashion; characteristic error function; computer simulations

The accuracy of phase shifting interferometry is limited by reference phase errors caused by nonlinearities in the phase shifter movements, calibration errors of this device, phase drifts during the measuring interval, and low frequency mechanical vibrations. Since the error depends on the phase to be measured in a sinusoidal fashion one can greatly reduce its influence on the measuring results. For this purpose a function also containing the characteristic error function, is fitted to the measured data. In a second step the error function is subtracted from the measured phase values. In most cases an error reduction by 1 order of magnitude seems achievable as has been demonstrated by computer simulations.