Advances in Single-Laser-Shot Femtosecond Coherent Anti-Stokes Raman Scattering Concentration and Temperature Measurements
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Single-laser-shot femtosecond (fs) coherent anti-Stokes Raman scattering (CARS) temperature measurements are performed at 5 kHz while suppressing the nonresonant background by polarization techniques. A chirped probe pulse is used to map the temporal dependence of the Raman coherence into the CARS signal frequency allowing for single-laser-shot measurements. A theoretical model and fitting code are presented, and good agreement is seen between the theory and experiment. By eliminating the nonresonant background, the diagnostic technique may be less sensitive to laser fluctuations as well as changes in nonresonant background levels due to changes in gas phase composition. Temperature measurements are reported for a steady near-adiabatic flame and for an unsteady hydrogen-air jet diffusion flame with nonresonant background suppression. In the jet diffusion flame, the measured temperature varied continuously from 500 to 1800 K, and sufficient signal levels are maintained to fit single-laser-shot spectra up to 1800 K. Copyright © 2012 by the American Institute of Aeronautics and Astronautics, Inc.
author list (cited authors)
Lucht, R., Richardson, D., Kulatilaka, W., Roy, S., & Gord, J.