Methane-stabilized He-Ne laser intercomparisons 1976

Three methane-stabilized lasers of differing optical and mechanical design have been intercompared. Frequency differences of the output radiations have been measured with the lasers stabilized by similar techniques. Agreement to ±2 parts in 10¹¹ is reported for lasers stabilized by a third derivative method. The stabilized frequency was found to be dependent on the method of stabilization. Frequency shifts of greater than 1 part in 10¹⁰ were recorded upon changing the method of stabilization. The effects were studied of the variation of modulation amplitude and the positioning of the detector used to generate the servocontrol signal for stabilization.