Testing micro devices with fringe projection and white-light interferometry

Optical sensors are very suitable for the analysis of microscopic structure s and micro devices. We compare two very promising methods: the white-light interferometry and the fringe projection technique for the application to this task. The fringe projection is very useful for fast measurement of obj ects with vertical dimensions of some mum. White-light interferometry is es pecially useful for highly resolved 3-D measurements. Furthermore, we prese nt a new technique. the scanning fringe projection (SFP), which enables abs olute 3-D measurements with one single grating period. (C) 2001 Elsevier Sc ience Ltd. All rights reserved.