<title>Reducing vibration effects in phase-shifting interferometry</title>

Abstract

ABSTRACT A method to reduce the sensitivity of phase-shifting interferometry to external vibrations without sacrificing lateralresolution is described. The returning interferogram is amplitude split to form two series of interferograms; a fast sampled,low spatial resolution data set and a slow sampled, high spatial resolution data set. The fast sampled set is used to calculatethe true phase increment between intensity measurements in the high spatial resolution data set and a generalized phaseextraction algorithm then uses these phase increments when calculating the topographical phases for this set. The measuredtopography thereby benefits from the best qualities of both data sets, providing increased vibration immunity withoutsacrificing high spatial resolution.Keywords: Interferometry, vibration, phase-shifting. 1. INTRODUCTION Phase-shifting interferometry' (PSI) is a technique used to measure surface topography by precisely measuring thephase angles in interferograms generated from combining light reflected from a known reference surface and the test object.The process acquires a sequence of interferograms while the reference phase is adjusted in a controlled manner. Theinterferogram intensities are described by,