Precision of multiplex CARS temperature measurements

Abstract

The potential measurement accuracy of coherent anti-Stokes Raman scattering (CARS) in N₂ was studied. A test was conducted using BOXCARS and nonresonant background suppression in a stabilized tube furnace from room temperature up to 1700 K. A computer program was developed for quick data processing. The influence of referencing on temperature measurement accuracy was analyzed. Absence of referencing produced errors up to 100 K on the mean temperature and on the standard deviation. Referencing with a time-averaged reference gave accurate values for the mean temperature. Referencing on a shot-to-shot basis improved the mean slightly and produced marginal gains in the standard deviation of individual measurements. The latter stays in the 10–50 K range in the temperature domain. Simulations show that part of the standard deviation (20%) is attributable to shot noise alone. The rest probably results from dye laser spectral noise and beam wandering.