<title>White light interferometry: innovative algorithms and performances</title>

Abstract

White light interferometry can be seen as a multichannel process since each wavelength constitutes an independent information carrier. The simultaneous observation of different wavelengths allows the absolute evaluation of optical path differences (OPD). Two basic detection schemes are available which are chosen as a function of the application requirements. In the first one, all wavelengths are superimposed on the photodetector and we get a single composite output signal. Therefore, the OPD has to be scanned in order to detect the interference fringe pattern which appears only for OPD shorter than the light source correlation length. The second scheme consists to separate optically the different wavelengths for a parallel detection and to measure the absolute value of the OPD without any mechanical displacement of the interferometer. This paper explores the case of surface profilometry for the presentation of the latest proposed signal processing algorithms and to compare the capabilities and perspectives of those two approaches.