PHASE DEMODULATION IN THE SPACE DOMAIN WITHOUT A FRINGE CARRIER

It is demonstrated that interference phase can be obtained from a fringe pattern using the spatial domain method known as spatial synchronous detection (direct interferometry) but without the usual fringe carrier (e.g. tilt) introduced into the interferometer. This is particularly useful in the study of transient events, where it is not always straightforward to introduce these carrier fringes. Spatial domain analysis is considerably faster than frequency domain (Fourier) methods, and could enable phase to be calculated in real time on relatively cheap personal computers. The main disadvantage of the new technique is that the sign of the recovered phase is lost, and must be inferred from object constraints.