Determining gas temperatures from laser scattering.

Lidar techniques may be applicable to inelastic, Raman scattering. When a light beam interacts with gas molecules, the energies of scattered photons may be increased or decreased relative to the incident photons. The Raman return signal can theoretically yield information on gas pressure, temperature, and molecular species concentration. The temperature can be calculated from the measurement of two scattered Raman rotational line intensities. Questions of measurement accuracy, line selection, and multiple line ratios are considered. The measurement apparatus is discussed together with the measurement techniques.