Date of Award

Spring 2001

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Electrical & Computer Engineering

Program/Concentration

Electrical Engineering

Committee Director

Amin N. Dharamsi

Committee Member

Ravindra P. Joshi

Committee Member

Glen W. Sachse

Call Number for Print

Special Collections LD4331.E55 L63 2001

Abstract

Gas filter correlation radiometry (GFCR) is a high-resolution, high-specificity technique for sensing gaseous species. A variation of absorption spectroscopy, GFCR has a long-proven record on orbital platforms for quantitative measurements of atmospheric constituents, as well as common usage in ground-based sensing applications. PMGFCR (Polarization-modulated GFCR) is a recent refinement of the technique with several advantages over the traditional method, including reducing the number of photodetectors required, increased sensitivity, and elimination of moving parts.

To date, no infrared remote sensors have successfully measured nitric oxide (NO) in vehicle exhaust due to spectral overlap by strong water vapor (H2Ov) absorption bands. The inherent specificity of PMGFCR provides sufficient suppression of H2Ov interference to measure vehicles with high NO emissions (l00's parts per million (ppm)).

This thesis investigates optimization of the PMGFCR to further reduce H2Ov interference. We use a computer model to demonstrate that with careful optical filter selection, accurate measurements of NO are feasible with the PM-GFCR, and optimize a laboratory bench-top PM-GFCR system to verify the predictions made with the computer model. Typical measurement error due to transient water vapor may be reduced from over 300 ppm equivalent NO to as little as 2 ppm.

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DOI

10.25777/b9zx-p395

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