Silicon microelement vibration testing using conventional and heterodyned time-average interferometry with automated temporal and spatial phase stepping

This paper focuses on the applicability of the temporal (TPS) and spatial carrier (SCPS) phase-shifting techniques to the time-average interferogram intensity modulation distribution determination. Both techniques use the same mathematical formulae, but in different domains: temporal and spatial ones. They are sensitive to different types of errors. The influence of main experimental errors: phase-step miscalibration, spatial carrier miscalibration, average intensity changes and intensity noise in both the presented techniques on the fringe function determination (vertical bar J(0)vertical bar or J(0)(2) in case of sinusoidal vibrations), is discussed. The techniques are compared to find the most appropriate one. The time-average technique with heterodyning for small vibration-amplitude measurements is also discussed. The application of the SCPS method to this technique is shown for the first time. (C) 2008 Published by Elsevier Ltd.