Gain measurement in the CO2laser discharge

In order to examine the CO
2
laser oscillation mechanism, a measurement was made of the unsaturated gain of CO
2
laser radiation in an active medium of gas discharge containing CO
2
, N
2
, and He. A two-beam optical balance method was used to measure the gain in an amplifier; the accuracy of the measurement was approximately 10 percent. The output of a CO
2
-N
2
-He laser was used as the radiation source. The absolute power of the probing beam, which has a diameter of approximately 5 mm, was maintained at approximately 15 mW. Saturation was not observed at probing signal levels up to 80 mW. Amplifier tubes with diameters of 55, 34, 12, and 5 mm were used. The dependence of the amplifier gain on the current density, pressure, composition of the gas mixture, and tube diameter was measured. Comparison was also made of the calculated and measured values for the laser population inversion.