Offset scanning and field widening: maintaining the radiometric performance of a Fourier transform spectrometer (FTS) with high spectral discrimination capability

James R. Engel; Rick K. Dorval

doi:10.1117/12.205559

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10 February 1995 Offset scanning and field widening: maintaining the radiometric performance of a Fourier transform spectrometer (FTS) with high spectral discrimination capability

James R. Engel, Rick K. Dorval

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Proceedings Volume 2366, Optical Instrumentation for Gas Emissions Monitoring and Atmospheric Measurements; (1995) https://doi.org/10.1117/12.205559
Event: Optical Sensing for Environmental and Process Monitoring, 1994, McLean, VA, United States

Abstract

Interferant spectral features that are stable in both time and optical frequency oftentimes can be made negligible with respect to spectral features of interest by simple data processing techniques such as absorbance subtraction. With varying degrees of success more sophisticated processing of these same spectra can reject these interferant spectral features even when not stable in time. Beyond this, a classic approach to rejecting spectral interferants is to operate at higher and higher spectral resolutions so that ultimately the interferant feature separates from the feature of interest so that it is of negligible effect as an interferant. For a given observation time this approach results in a loss of radiometric sensitivity. A further reduction in radiometric sensitivity may occur since the maximum allowed etendue in a fixed parameter system must also be decreased to accommodate the higher resolution. (This reduction in etendue is more likely in the instance of a process control application as opposed to an open path monitoring application). The use of offset scanning and field widening as techniques for regaining this lost sensitivity are discussed.

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James R. Engel and Rick K. Dorval "Offset scanning and field widening: maintaining the radiometric performance of a Fourier transform spectrometer (FTS) with high spectral discrimination capability", Proc. SPIE 2366, Optical Instrumentation for Gas Emissions Monitoring and Atmospheric Measurements, (10 February 1995); https://doi.org/10.1117/12.205559

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