title: Development of multipoint vibrational coherent anti-Stokes Raman spectroscopy for flame applications.
abstract: A novel technique for coherent anti-Stokes Raman spectroscopy (CARS) measurements in multiple points is presented. In a multipass cavity the pump and Stokes laser beams are multiply reflected and refocused into a measurement volume with an adjustable number of separated points along a line. This optical arrangement was used in a vibrational CARS setup with planar BOXCARS phase-matching configuration. The CARS spectra from spatially separated points were recorded at different heights on a CCD camera. Measurements of temperature profiles were carried out in the burned gas zone of a premixed one-dimensional flame to demonstrate the applicability of this method for temperature measurements in high-temperature regions. The ability to measure in flames with strong density gradients was demonstrated by simultaneous measurements of Q-branch spectra of N2 and CO in a Wolfhard-Parker burner flame. Interference phenomena found in multipoint spectra are discussed, and possible solutions are proposed. Merits and limitations of the technique are discussed.
authors.affiliation: Division of Combustion Physics, Lund Institute of Technology, P.O. Box 118, S-221 00 Lund, Sweden.
authors.forename: Mikael
authors.initials: M
authors.lastname: Afzelius
authors.forename: Per-Erik
authors.initials: PE
authors.lastname: Bengtsson
authors.forename: Joakim
authors.initials: J
authors.lastname: Bood
authors.forename: Christian
authors.initials: C
authors.lastname: Brackmann
authors.forename: Alfred
authors.initials: A
authors.lastname: Kurtz