Abstract: A method and apparatus for stabilizing the frequency of a laser beam is provided wherein the laser beam from a laser cavity is sampled and dispersed. A pair of detectors detect any energy sharing of the laser beam at the desired output frequency with laser beams at a frequency above and below the desired frequency to produce an error signal. The error signal is fed back to the laser cavity to correct the distance between opposite ends of the cavity to adjust the wave length of the laser beam to emit amplified light at the desired frequency.