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Proceedings Paper

Imaging open-path Fourier transform infrared spectrometer for 3D cloud profiling
Author(s): Julia R. Dupuis; David J. Mansur; James R. Engel; Robert Vaillancourt; Lori Todd; Kathleen Mottus
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Paper Abstract

An imaging open-path Fourier transform infrared (I-OP-FTIR) spectrometer is being developed for real-time three-dimensional cloud profiling. The system employs a single modulator and a novel optical configuration which projects an array of angularly dispersed IR beams, each of which exhibits comparable throughput to a single channel OP-FTIR, to an array of respective retroreflector arrays remotely located at the opposite side of the test grid. The return light from each retroreflector array is imaged onto respective detectors that record the spatially-resolved interferograms which are subsequently transformed and analyzed for molecular content via advanced multicomponent algorithms. The result is a capability to sensitively, quantitatively, and simultaneously measure the molecular absorbance and associated concentration-pathlength of an open release plume over a spatial region. Use of two or more I-OP-FTIR sensors around the perimeter of the release allows for tomographic reconstruction of the concentration map of each molecular species contained in the plume. This approach realizes the high sensitivity of an OP-FTIR spectrometer without adding the expense and logistical difficulties associated with installing a large number of spectrometer units required for the cloud profiling application. In addition, the active spectral measurement supports detection in zero temperature contrast conditions where the plume is the same temperature as the background. A further reduction in cost and weight is achieved through the use of low-cost plastic press molded retroreflector arrays to return the spatially dispersed open path beams.

Paper Details

Date Published: 2 October 2007
PDF: 11 pages
Proc. SPIE 6756, Chemical and Biological Sensors for Industrial and Environmental Monitoring III, 675609 (2 October 2007); doi: 10.1117/12.732519
Show Author Affiliations
Julia R. Dupuis, OPTRA, Inc. (United States)
David J. Mansur, OPTRA, Inc. (United States)
James R. Engel, OPTRA, Inc. (United States)
Robert Vaillancourt, OPTRA, Inc. (United States)
Lori Todd, Univ. of North Carolina/Chapel Hill (United States)
Kathleen Mottus, Univ. of North Carolina/Chapel Hill (United States)

Published in SPIE Proceedings Vol. 6756:
Chemical and Biological Sensors for Industrial and Environmental Monitoring III
Kenneth J. Ewing; James B. Gillespie; Pamela M. Chu; William J. Marinelli, Editor(s)

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