Abstract

Experimental CARS spectra of the Q-branch (v = 0-v = 1) of NO gas at different temperatures (300–1400 K) has been performed with a folded BOXCARS technique that can provide high spatial resolution for diagnostic purposes. A theoretical calculation taking into account the laser linewidth and lineshape is presented. By comparing the theoretical spectra with the experimental ones, the point temperatures measured by the CARS method are determined. The measurement accuracy of the method is discussed. CARS measurements have also been performed for various NO gas pressure (0.04–1 atm) in order to study the pressure dependence of the CARS spectral shape. A concentration measurement method using the intensity of virbration–rotational line is discussed. It is found that the concentration dependence of line intensity is in agreement with the theoretical result for high J values.

© 1991 Optical Society of America