Investigation of the radiation noise of a helium–cadmium laser pumped by a transverse hf discharge

An investigation was made of the noise of the cw radiation from a helium–cadmium laser (pumped by a transverse hf discharge) at wavelengths of 533.7 and 537.8 nm. It was established that in the frequency range between 20 Hz and 110 MHz the main causes of noise in the output radiation are pulsations of the discharge current at the mains frequency and its harmonics, and also transverse mode beats. When these disturbances were eliminated, the signal/noise ratio in this laser did not exceed 0.1%.