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Journal of Electronic Imaging

Unambiguous interferometric surface profilometry using ferroelectric liquid crystal modulators
Author(s): Mark L. Begbie; John Paul Lesso; Wilson Sibbett; Miles J. Padgett
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Paper Abstract

We present a surface profiler that produces unambiguous, fringe-free, surface profiles. Each point in the output image has a modulus of the complex degree of coherence (|µxy|) which varies monotonically as the optical path difference is increased from zero. To calculate |µxy|, the profiler incorporates a novel Stokes polarimeter employing a polarization image splitter and ferroelectric liquid crystal wave plates. Rapid wave plate addressing, coupled with the image splitter, allows data to be collected in three video frames. We observe that manufacturing inaccuracies in wave plate retardance and alignment introduce an error to the calculated |µxy| which can reintroduce ambiguity into the height measurement. We present a numerical correction which allows recovery |µxy| from the measured data, thereby returning us to an unambiguous surface profile. Results for various surfaces, showing the effects of systematic error and applied correction terms, are given.

Paper Details

Date Published: 1 January 2001
PDF: 5 pages
J. Electron. Imag. 10(1) doi: 10.1117/1.1313241
Published in: Journal of Electronic Imaging Volume 10, Issue 1
Show Author Affiliations
Mark L. Begbie, Univ. of Glasgow (United Kingdom)
John Paul Lesso, Univ. of St. Andrews (United Kingdom)
Wilson Sibbett, Univ. of St. Andrews (United Kingdom)
Miles J. Padgett, Univ. of Glasgow (United Kingdom)

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