Laser pulse profile control by modulating relaxation oscillations

摘要

A method and apparatus for controlling the form and timing of pulses emitted by a high-power solid-state laser, without the need for complex feedback circuits. The width and peak intensity of relaxation pulses emitted by the laser are controlled by use of an acousto-optic modulator (14) installed in the laser cavity, to lock the relaxation pulses to the frequency of radio-frequency (rf) control signals applied to the modulator. The number and average rate at which the pulses are emitted from the laser are independently controlled by varying the duty cycle of diodes (20) used to pump solid-state amplifiers (18) installed in the laser cavity. Short pump pulses can be selected to deliver only a few relaxation pulses from the laser, or longer pump pulses can be selected to deliver large numbers of relaxation pulses during each pump pulse. Feedback control of the modulator (14) is not needed because the pumping rate is uniform for the duration of each pump pulse and, therefore, the peak intensities of relaxation pulses emitted by the laser are relatively uniform. Accordingly, the solid-state laser can be conveniently controlled to produce a desired average power output while maintaining good beam quality.