SINGLE-PULSE COHERENT ANTI-STOKES RAMAN SCATTERING
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Date
1976
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Publisher
Ohio State University
Abstract
Coherent anti-Stokes Raman scattering (CARS) is used for the measurement of species concentrations and temperature distributions in molecular media. The method is based upon the generation of two high-power laser beams--one used as the pump and the other as a Stokes component--and the subsequent mixing of the beams in the molecular medium. The anti-Stokes spectrum of the medium can be obtained by tuning the Stokes beam. This method, however, requires excellent frequency stability and considerable measurement time. A new CARS technique employing a broad-band dye laser in conjunction with a single-mode ruby laser allows spatially and temporally resolved species concentration and temperature measurements with a single laser pulse. The detection of the anti-Stokes spectrum is accomplished by means of a grating spectrometer and an optical multi-channel analyzer. With this technique, the stringent frequency-stability requirement is significantly relaxed. Experimental results for $H_{2}$ and HF gases, which demonstrate the advantages of this technique, will be presented. In addition, the pressure dependence of the anti-Stokes intensity for several gases including CO and $CH_{4}$ will be presented and the practical implications of the method discussed.
Description
Author Institution: Systems Research Laboratories Inc.; Air Force Aero, Propulsion Laboratory