Coherence scanning in a geometrically desensitized interferometer

Leslie L. Deck; Peter J. de Groot; Xavier Colonna de Lega

doi:10.1117/12.334345

29 December 1998 Coherence scanning in a geometrically desensitized interferometer

Leslie L. Deck, Peter J. de Groot, Xavier Colonna de Lega

Proceedings Volume 3520, Three-Dimensional Imaging, Optical Metrology, and Inspection IV; (1998) https://doi.org/10.1117/12.334345
Event: Photonics East (ISAM, VVDC, IEMB), 1998, Boston, MA, United States

Abstract

A geometrically desensitized interferometer (GDI) uses two beams incident on the same sample area at different angles of incident to generate an interference pattern with an equivalence wavelength larger than the illumination wavelength. The instrument is well adapted to the metrology of both smooth and rough samples that are beyond the range of conventional interferometers, while providing more accuracy than conventional moire techniques. In this paper, we extend the capabilities of a GDI with an equivalent wavelength of 12.5 micron using coherence scanning in a manner similar to that of scanning white light interferometry. We also present new analysis techniques to accommodate speckle phenomena that can be more prominent in GDI than in white light interferometry. Our scanning GDI can rapidly characterize the surface flatness and relative heights of discontinuous surface features over large measurement volumes.

Citation Download Citation

Leslie L. Deck, Peter J. de Groot, and Xavier Colonna de Lega "Coherence scanning in a geometrically desensitized interferometer", Proc. SPIE 3520, Three-Dimensional Imaging, Optical Metrology, and Inspection IV, (29 December 1998); https://doi.org/10.1117/12.334345

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