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Proceedings Paper

Effects of incomplete light extinction in frequency-agile, rapid scanning spectroscopy
Author(s): D. A. Long; S. Wójtewicz; J. T. Hodges
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Paper Abstract

The effect of finite beam extinction ratio on the precision and accuracy of cavity ring-down decay time constant measurements was examined using the frequency-agile, rapid scanning, cavity ring-down spectroscopy (FARS-CRDS) technique. This new approach to CRDS uses a waveguide-based electro-optic phase modulator (EOM) to provide a laser beam extinction ratio as high as 80 dB: a value that is ≈30 dB greater than that typically achieved with acousto-optic-modulator- based beam switches. We find that the observed measurement precision scales inversely with extinction ratio, such that an EOM enables measurement of the cavity ring-down decay time with a relative precision of ≈8×10-5. We demonstrate that insufficient extinction can be the dominant cause of statistical uncertainty for extinction ratios below 60 dB. Furthermore, insufficient extinction can result in non-exponential decays, which cause systematic measurement biases in cavity losses and absorption.

Paper Details

Date Published: 29 May 2013
PDF: 6 pages
Proc. SPIE 8726, Next-Generation Spectroscopic Technologies VI, 87260O (29 May 2013); doi: 10.1117/12.2016056
Show Author Affiliations
D. A. Long, National Institute of Standards and Technology (United States)
S. Wójtewicz, National Institute of Standards and Technology (United States)
Nicolaus Copernicus Univ. (Poland)
J. T. Hodges, National Institute of Standards and Technology (United States)


Published in SPIE Proceedings Vol. 8726:
Next-Generation Spectroscopic Technologies VI
Mark A. Druy; Richard A. Crocombe, Editor(s)

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