Abstract
An experimental arrangement of a Michelson type CO2 laser for plasma diagnostic studies of ac discharges is described. The principle of the apparatus is based on the phenomena of strong competition between the rotational transitions. If a phase shift is caused by the plasma to be studied, the intensity distribution of the lasing transitions is changed. The system has been used successfully for measuring (with a wavelength of 10.6 μ) changes in refractive index on the order of 10−9.