Unambiguous interferometric surface profilometry using ferroelectric liquid crystal modulators

Begbie, M.L., Lesso, J.P., Sibbett, W. and Padgett, M. (2001) Unambiguous interferometric surface profilometry using ferroelectric liquid crystal modulators. Journal of Electronic Imaging, 10(1), 263 -267. (doi: 10.1117/1.1313241)

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Publisher's URL: http://dx.doi.org/10.1117/1.1313241


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 (|μ<sub>xy</sub>|) which varies monotonically as the optical path difference is increased from zero. To calculate |μ<sub>xy</sub>|, 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 |μ<sub>xy</sub>| which can reintroduce ambiguity into the height measurement. We present a numerical correction which allows recovery |μ<sub>xy</sub>| 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.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Padgett, Professor Miles
Authors: Begbie, M.L., Lesso, J.P., Sibbett, W., and Padgett, M.
Subjects:Q Science > QC Physics
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Journal of Electronic Imaging

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