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Proceedings Paper

Precision heterodyne ellipsometry with an improved conic fitting algorithm
Author(s): Lionel R. Watkins; Matthew J. Collett
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Paper Abstract

Ellipsometers based on heterodyne interferometers are inherently capable of precise measurements, with the ellipsometric angles determined from the amplitude and phase of a pair of quadrature signals. These signals are generally displayed as a Lissajous figure and the primary limitation to accuracy is determined by the goodness-of-fit to the ellipse, especially for ellipses with high ellipticity. In this paper we describe an improvement to the ellipse­ fitting algorithm of Halir & Flusser. A Michelson interferometer was constructed and a polarizer-quarterwave plate combination used to generate ellipses of moderate to extreme ellipticity. We show experimentally that our method yields excellent fits, even for axis ratios approaching 300: 1, yielding a one-sigma error of 0.5 mrad (less than λ/10000) in the presence of measurement noise.

Paper Details

Date Published: 22 June 2013
PDF: 5 pages
Proc. SPIE 8769, International Conference on Optics in Precision Engineering and Nanotechnology (icOPEN2013), 87692F (22 June 2013); doi: 10.1117/12.2019043
Show Author Affiliations
Lionel R. Watkins, The Univ. of Auckland (New Zealand)
Matthew J. Collett, The Univ. of Auckland (New Zealand)

Published in SPIE Proceedings Vol. 8769:
International Conference on Optics in Precision Engineering and Nanotechnology (icOPEN2013)
Chenggen Quan; Kemao Qian; Anand Asundi, Editor(s)

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