White-light Interferometry with an Extended Zoom Range

Optical sensors are designed usually for microscopic or for macroscopic applications. White-light interferometry on the other hand enables high-resolution measurements to be made for small and for large fields. In this paper we present a flexible set-up that can be used for both microscopic and macroscopic applications. The magnification can easily be changed in seconds and the zoom range is greater than 160. This set-up is especially designed for the investigation of optically rough surfaces. A novel filtering technique enables fast and accurate data acquisition and evaluation with standard hardware components. Further we demonstrate results of roughness measurements in different scales.