Development of a millimeter-wave sensor for environmental monitoring

Nachappa Gopalsami; Sasan Bakhtiari; Apostolos C. Raptis

doi:10.1117/12.224235

13 October 1995 Development of a millimeter-wave sensor for environmental monitoring

Nachappa Gopalsami, Sasan Bakhtiari, Apostolos C. Raptis

Proceedings Volume 2558, Millimeter and Submillimeter Waves II; (1995) https://doi.org/10.1117/12.224235
Event: SPIE's 1995 International Symposium on Optical Science, Engineering, and Instrumentation, 1995, San Diego, CA, United States

Abstract

A millimeter-wave (mm-wave) sensor in the frequency range of 225-315 GHz is being developed for continuous emission monitoring for airborne effluents from industrial sites with applicability to environmental compliance monitoring and process control. Detection of chemical species is based on measuring the molecular rotational energy transitions at mm- wave frequencies. The mm-wave technique offers better transmission properties than do optics in harsh industrial environemnts such as those with smoke, dust, aerosols, and steam, as well as in adverse atmospheric conditions. Laboratory million-meter with this technology. Proof of principle of the open-path system has been tested by releasing and detecting innocuous chemicals in the open air. The system uses a monostatic radar configuration with transmitter and receiver on one side of the plume to be measured an a corner cube on the other side. A wide-band swept-frequency mm-wave signal is transmitted through the plume, and the return signal from the corner cube is detected by a hot-electron-bolometer. Aborption spectra of the plume gases are measured by comparing the return signal processing technique based on deconvolution, we have shown a high specificity of detection for resolving individual chemicals from a mixture. This technology is applicable for real-time measurement of a suite of airborne gases and vapors emitted from vents and stacks of process industries. A prototype sensor is being developed for wide-area monitoring of industrial sites and in-place monitoring of stack gases.

Citation Download Citation

Nachappa Gopalsami, Sasan Bakhtiari, and Apostolos C. Raptis "Development of a millimeter-wave sensor for environmental monitoring", Proc. SPIE 2558, Millimeter and Submillimeter Waves II, (13 October 1995); https://doi.org/10.1117/12.224235

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