Pollutant Detection by Absorption Using Mie Scattering and Topographic Targets as Retroreflectors

Abstract

Remote pollutant measurement by absorption using topographical reflectors or atmospheric Mie scattering as a distributed reflector offers increased range and sensitivity compared to that achieved by Raman or resonance backscattering methods. The use of topographical reflectors offers the advantage of a single-ended absorption measurement for ranges up to 10 km and sensitivities to less than 0.01 ppm for a 10-mJ, 100-nsec transmitted pulse. The distributed Mie reflector permits absorption measurements over a depth cτ/2, determined by the pulse length τ, and allows ranging by time-of-flight measurement. For a 100-mJ, 100-nsec pulse sensitivities to 0.3 ppm at a 15-m depth resolution to ranges of 1–4 km are possible. This sensitivity is 10⁴ to 10⁵ times better than that achieved by the Raman method.

© 1973 Optical Society of America

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