Frequency stabilization of a 0.633-microm He-Ne longitudinal Zeeman laser

A new method of stabilizing the output frequency of a He-Ne laser in a longitudinal magnetic field has been developed. With simple modifications to a standard He-Ne laser tube we obtain a frequency stability of <1 MHz (<10(-9)) for an averaging time of 1 sec and a long term (5 months) frequency reproducibility of ~ +/-1 MHz.