Vision-based system for automatic stabilization of mode,beam steer,and output power of a high-power laser

As advancements in laser technology result in higher-power devices, increased thermal loads experienced by resonator optical components generate instabilities in the output beam. Consequently, methods for maintaining and optimizing output-beam parameters are necessary for efficient long-term operation. This study examines a vision-based feedback control system which monitors a sampled cross-sectional image of the laser's output, and regulates both cavity mirrors, as well as the excitation level, to stabilize beam uniformity, beam steer, and output-power level.The system optimizes the output-power distribution achievable from a given laser, while significantly reducing beam steering effects. Direction of beam propagation is restricted to within 60 rad of the desired setpoint, while the output power is stabilized to within 4%. Results clearly document a considerable improvement in laser performance through maximization of beam uniformity, minimization of beam steering, and stabilization of total output power. As such, an important degree of consistency and repeatability in output-beam parameters, essential to precision laser applications, is easily achieved. Valuable diagnostic capabilities pertaining to output beam intensity and energy profiles are also incorporated into the control system. These data may be monitored on-line or stored for subsequent analysis.