White-light interferometry with reference signal

Joanna Schmit; Artur G. Olszak; Shawn D. McDermed

doi:10.1117/12.472209

20 June 2002 White-light interferometry with reference signal

Joanna Schmit, Artur G. Olszak, Shawn D. McDermed

Proceedings Volume 4777, Interferometry XI: Techniques and Analysis; (2002) https://doi.org/10.1117/12.472209
Event: International Symposium on Optical Science and Technology, 2002, Seattle, WA, United States

Abstract

White light interferometer (WLI) has become a common tool for measuring surfaces with large height range and/or roughness. Typically, the object is scanned through focus, thus varying the optical path difference (OPD) between the object and reference beams. The rate of the OPD change affects the quality and accuracy of the surface measurement. For high quality measurements a scanning device is often enhanced by a closed loop feedback while the scanning speed is assumed to be known and constant. In this paper we describe a white light interferometer that yields excellent results without requiring a high-end scanner. These results are achieved by embedding an additional interferometer with a long coherence length source that provides an interferometric reference signal that is used to monitor the motion of the scanner during each measurement in real time. The information about the scanner motion is then used in a WLI algorithm. This yields significant improvements in both the accuracy and repeatability of topography measurements.

Citation Download Citation

Joanna Schmit, Artur G. Olszak, and Shawn D. McDermed "White-light interferometry with reference signal", Proc. SPIE 4777, Interferometry XI: Techniques and Analysis, (20 June 2002); https://doi.org/10.1117/12.472209

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