Testing micro devices with fringe projection and white-light interferometry

Optical sensors are very suitable for the analysis of microscopic structures 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 objects with vertical dimensions of some μm. White-light interferometry is especially useful for highly resolved 3-D measurements. Furthermore, we present a new technique, the scanning fringe projection (SFP), which enables absolute 3-D measurements with one single grating period.