Frequency stabilization of a radio frequency excited $CO2$ laser using the photoacoustic effect

A frequency and a power of rf excited $CO2$ laser are stabilized using the photoacoustic effect generated from the laser itself. As the radiation intensity in a laser resonator changed, the pressure of laser medium gas changed due to its photoacoustic effect. A condenser microphone built in the resonator is used to convert delicate variations in the pressure into voltage signals to be used as input signals for lock-in stabilizer. As a result of stabilizing the frequency and power of the laser oscillated from $P(20)$ line, at the apex of gain curve, the relative stability of the optical frequency and the rate of change in laser power are $5.57×10−8$ and 9.3%, respectively.