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Optical Path Switching Based Differential Absorption Radiometry for Substance DetectionA system and method are provided for detecting one or more substances. An optical path switch divides sample path radiation into a time series of alternating first polarized components and second polarized components. The first polarized components are transmitted along a first optical path and the second polarized components along a second optical path. A first gasless optical filter train filters the first polarized components to isolate at least a first wavelength band thereby generating first filtered radiation. A second gasless optical filter train filters the second polarized components to isolate at least a second wavelength band thereby generating second filtered radiation. The first wavelength band and second wavelength band are unique. Further, spectral absorption of a substance of interest is different at the first wavelength band as compared to the second wavelength band. A beam combiner combines the first and second filtered radiation to form a combined beam of radiation. A detector is disposed to monitor magnitude of at least a portion of the combined beam alternately at the first wavelength band and the second wavelength band as an indication of the concentration of the substance in the sample path.
Document ID
20000090560
Acquisition Source
Langley Research Center
Document Type
Other - Patent
Authors
Sachse, Glen W. (NASA Langley Research Center Hampton, VA United States)
Date Acquired
September 7, 2013
Publication Date
May 2, 2000
Subject Category
Optics
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.
Patent
NASA-Case-LAR-15818-1|US-Patent-6,057,923
Patent Application
US-Patent-Appl-SN-082355|US-Patent-Appl-SN-290954

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