Gas spectroscopy based upon fiber optic systems is emerging as an important contributor to the art of remote measurement. To date two generic application sectors have emerged. The first is to make measurements in difficult and hazardous environments for which an integrated and passive optical source is extremely attractive. An optical fiber equipped with suitable collimation optics can furnish such a source. These systems have been utilized to measure gas flow and concentration in gas turbine engines and in hazardous chemical processes. The second applications sector lies in monitoring geographically widely spread locations at which the same measurement is continuously required. These occur for example in oil and gas exploration and processing systems and petrochemical plant. In this case it is the transmission capabilities of the optical fiber which are especially attractive. The optical fiber transmission medium implies that any optical signals which are used in the spectroscopic measurement lie in the near infra red with the absorption line strengths for most interesting species are relatively weak. However, modern source: detector combinations lead to very useful performance despite the weaker line strengths. This paper presents an analysis of the principal factors which determine system performance and illustrates these with some specific applications examples. Finally, we briefly explore the prospects offered by non-linear systems to produce remote spectroscopic measurements operating in the mid infra red but interohated and energized in the near infra red.

Date Published: 28 April 1999
PDF: 12 pages
Proc. SPIE 3666, International Conference on Fiber Optics and Photonics: Selected Papers from Photonics India '98, (28 April 1999); doi: 10.1117/12.347967

Published in SPIE Proceedings Vol. 3666:
International Conference on Fiber Optics and Photonics: Selected Papers from Photonics India '98
Anurag Sharma; Banshi Dhar Gupta; Ajoy K. Ghatak, Editor(s)