Active stabilisation of laser resonators

摘要

Even "stable" lasers pulsate (breathe), that is to say that their mode profile undergoes fluctuations with periods of from a few minutes up to hours. This is particularly true during the warm-up phase of the laser. Power measurement can scarcely detect these fluctuations, even though they are the source of many problems with power lasers, especially in the case of sensitive processes. The novel device continuously regulates laser resonators to optimum constant mode. The device consists of a motor-driven adjustment mechanism on at least one of the resonator mirrors, a simple measurement device for the mode profile, and a regulator unit, for example a program-controlled computer. The novel method consists in that the regulator unit continuously actively keeps the resonator optimally adjusted by means of small movements of the resonator mirror. In addition, "search runs" are executed at selectable time intervals, by means of which the mode is trimmed to the absolute maximum. <IMAGE>