Controlled timewise redistribution of laser energy

An electronic feedback circuit is described which has been used in a Nd:glass high-power laser system for converting the spiky light emission into a smooth near-rectangular output of adjustable intensity and duration. The feedback circuit is also capable of converting the laser emission into a stroboscopic output of frequency of several hundreds of kilohertz or into a -switched high-intensity output. The attractive feature of the system is that the change from one type of laser operation into the other does not require any modification to the circuit, but only a simple readjustment of a few control knobs. The feedback system incorporates a high-current fast photodiode, a Pockels-cell shutter, and a pulser. The main innovation of the present electronic feedback circuit over previously proposed systems is the ability to set the Pockels cell at any point of its transmission curve. This feature will be demonstrated to be of decisive importance in smoothing out the laser emission and in converting the spiky light output into a series of periodic light pulses.