Laser radiation source for practical interferometry

A study was made of a stabilized laser source based on a two-mode helium-neon ring laser with a circularly anisotropic resonator. This laser emitted at 0.63 μ. The frequency was stabilized by comparing the frequencies of the Zeeman beats between the orthogonal modes of the opposite waves. The relative frequency stability achieved in this way was 8.8×10^–12 in an averaging time of 1 min.