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Proceedings Paper

Interferometer with dynamic reference
Author(s): Jan Liesener; Hans J. Tiziani
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Paper Abstract

Interferometric testing of optical surfaces is problematic when strong asphericities are present. The spatial frequencies of the interference fringes exceed the detector resolution where the slope difference between test beam and reference beam is too large. CGHs are frequently used to avoid this effect but availability and flexibility is a problem. Alternatively we propose a new method to extend the dynamic range of interferometric measurements. For this purpose the reference beam in an interferometer is adapted. An active element containing a spatial light modulator (SLM) is used to vary the slope of the reference beam within a few degrees in both x- and y-directions. Hereby different areas of the interferogram become evaluable. Furthermore the active element can introduce phase shifts necessary for the phase shift interferometry algorithms. Several interferograms with different reference beam slopes are recorded and finally the phase functions are "stitched" together. By using an SLM for the reference beam tilt, no mechanical motion of any hardware which would limit the accuracy is necessary. A calibration of the tilts can be performed with interferometric accuracy.

Paper Details

Date Published: 26 February 2004
PDF: 8 pages
Proc. SPIE 5252, Optical Fabrication, Testing, and Metrology, (26 February 2004);
Show Author Affiliations
Jan Liesener, Univ. Stuttgart (Germany)
Hans J. Tiziani, Univ. Stuttgart (Germany)

Published in SPIE Proceedings Vol. 5252:
Optical Fabrication, Testing, and Metrology
Roland Geyl; David Rimmer; Lingli Wang, Editor(s)

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