INTERFEROGRAM ANALYSIS BASED ON THE DATA-DEPENDENT SYSTEMS METHOD FORNANOMETROLOGY APPLICATIONS

A spatial method of wave-front phase detection from an interferogram i s presented. The method uses data-dependent systems methodology, an ap proach that extends and improves the way the stochastic autoregressive moving average models are obtained and interpreted. Its application t o interference data addresses the fundamental problem of recovering th e self-coherence function commonly used to retrieve the wave-front pha se. The self-coherence function is efficiently computed by means of a complex autoregressive model and is used for surface reconstruction. T he method is shown to be robust and suitable for surface testing. The correspondence of the data-dependent systems methodology and its physi cal meaning as related to the classical interferometry are presented. The theoretical development is illustrated by experimental implementat ion, with the results obtained from one- and two-dimensional interfero metric fringe analysis of a computer hard disk.