Abstract

There are several uses for fast quantitative measurements (at kilohertz to megahertz rates) of atomic density. Accurate transient density measurements with microsecond resolution are needed to characterize transient phenomena in discharges such as charge exchange, recombination, or electronic excitation. Reaction rates and products in flowing vapor streams can be diagnosed via transient density measurements. Quantitative density measurements that are based on absorption require concurrent measurements of line shape in a dynamic vapor flow. Several authors have developed techniques for determining number density that rely on measuring dispersion. Bjorklund et al.^1,2 measure the FM to AM conversion of a phase-modulated beam due to differences in phase shift of the sidebands caused by atomic dispersion. Others have used interferometric techniques to measure index of refraction changes.^3,4

© 1988 Optical Society of America