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Design considerations in high-sensitivity off-axis integrated cavity output spectroscopy

Moyer, E. J. and Sayres, D. S. and Engel, G. S. and St. Clair, J. M. and Keutsch, F. N. and Allen, N. T. and Kroll, J. H. and Anderson, J. G. (2008) Design considerations in high-sensitivity off-axis integrated cavity output spectroscopy. Applied Physics B: Lasers and Optics, 92 (3). pp. 467-474. ISSN 0946-2171. doi:10.1007/s00340-008-3137-9.

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Off-axis integrated cavity output spectroscopy (OA-ICOS) has generated much interest because it potentially allows highly sensitive field measurements with robust optical alignment. We discuss here design choices involved in design of an OA-ICOS instrument and how these choices impact instrument sensitivity, using as our example the design of the Harvard ICOS isotope instrument, which demonstrates the highest reported sensitivity for mid-IR OA-ICOS (2.4×10⁻¹¹ cm⁻¹Hz^(-1/2) at 6.7 μm, obtained during measurements of water vapor isotopologues H₂O, HDO, and H₂  ¹⁸O in the laboratory and onboard NASA’s WB-57 high-altitude research aircraft). We compare the sensitivity of several OA-ICOS instruments with differing design parameters, show how comparisons are hindered by differing definitions of instrument performance metrics, and suggest a common metric of MDA_(meas), the fractional absorption equivalent to 1σ uncertainty in an actual measurement, normalized to 1 s integration. We also note that despite an emphasis on sensitivity in the literature, in the Harvard ICOS isotope instrument and likely also similar instruments, systematic errors associated with fitting of the baseline laser power are of equal importance to total measurement uncertainty.

Item Type:Article
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St. Clair, J. M.0000-0002-9367-5749
Additional Information:© 2008 Springer-Verlag. Received 20 March 2008; Revised 10 July 2008; Published 16 August 2008. We are grateful to V. Kasyutich and W. Zhao for helpful discussions on sensitivity metrics (though we also want to exempt them from responsibility for any opinions expressed in this article; those should be assigned to the authors alone). We also thank two anonymous reviewers. Funding for this work was provided in part by a NASA Instrument Incubator Program grant and a NOAA Postdoctoral Fellowship in Climate and Global Change.
Funding AgencyGrant Number
National Oceanic and Atmospheric Administration (NOAA)UNSPECIFIED
Subject Keywords:Optical Cavity; Quantum Cascade Laser; Electronic Noise; Minimum Detectable Absorption; Tunable Diode Laser Absorption Spectroscopy
Issue or Number:3
Record Number:CaltechAUTHORS:20200324-110551180
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Official Citation:Moyer, E., Sayres, D., Engel, G. et al. Design considerations in high-sensitivity off-axis integrated cavity output spectroscopy. Appl. Phys. B 92, 467 (2008).
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:102084
Deposited By: Tony Diaz
Deposited On:24 Mar 2020 18:26
Last Modified:16 Nov 2021 18:08

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