Applications of wideband FM spectroscopy to environmental and industrial process monitoring

James F. Kelly; Bret D. Cannon; Steven W. Sharpe; Robert L. Sams; Thomas A. Blake

doi:10.1117/12.292717

31 October 1997 Applications of wideband FM spectroscopy to environmental and industrial process monitoring

James F. Kelly, Bret D. Cannon, Steven W. Sharpe, Robert L. Sams, Thomas A. Blake

Proceedings Volume 3127, Application of Lidar to Current Atmospheric Topics II; (1997) https://doi.org/10.1117/12.292717
Event: Optical Science, Engineering and Instrumentation '97, 1997, San Diego, CA, United States

Abstract

Progress in understanding and developing methodologies to do low frequency, wideband FM-coding on a variety of laser sources is presented. Several practical FM-coding formats have been studied and compared for use with large, 'slow' IR detectors. The objective of this work is to establish practical methods of doing long baseline absorbance measurements in the lower troposphere that could be degraded by large integrated effects of optical turbulence. A comparative study of producing high index modulation on laser diodes and other practical laser sources is presented, along with numerical simulations and experimental result of detected signal strength. These results are presented with the intent of illustrating useful laser sources and FM- coding schemes that could allow effective detection of trace atmospherically broadened absorbance signatures. Results of field measurement will be discussed in order to suggest further improvement for this technique. Signal-to-noise issues and effects of phase distortion will be outlined with the view of suggesting correct optimization of laser transmitter and detector/preamp subsystems for these types of FM signal recovery. Finally, efforts at developing thermo-optically stable external electro-optic modulators will also be discussed.

Citation Download Citation

James F. Kelly, Bret D. Cannon, Steven W. Sharpe, Robert L. Sams, and Thomas A. Blake "Applications of wideband FM spectroscopy to environmental and industrial process monitoring", Proc. SPIE 3127, Application of Lidar to Current Atmospheric Topics II, (31 October 1997); https://doi.org/10.1117/12.292717

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