Active dispersion control for a Doppler broadened laser

The present invention broadly relates to a laser clock and, more particularly, is concerned with a servo control system that improves the long-term stability of the clock by controlling errors due to optical dispersion effects caused by aging of the laser and change in its temperature. A method for controlling the output of a laser in a laser clock to compensate for changes in the output of the laser due to optical dispersion resulting from laser aging and changes in laser temperature is described, which comprises, comparing the output frequency of the laser clock with a standard of known frequency, such as an atomic clock. Calculating the change in laser discharge current corresponding to any difference between the laser clock frequency and the standard required to adjust the laser clock frequency to a predetermined frequency value, and adjusting the laser discharge current to a value corresponding to the predetermined laser clock frequency.