Patent ID: 8908735

Claim:
A method of operating a pulsed gas discharge laser system, the method comprising: producing, at a seed laser oscillator including a first gas discharge laser chamber, an output comprising a laser output light beam of pulses; directing the output produced at the seed laser oscillator through a regenerative ring power amplification stage containing an amplifying gain medium in a second gas discharge laser chamber; amplifying the produced output within the regenerative ring power amplification stage to thereby form a laser system output comprising a laser output light beam of pulses, the regenerative ring power amplification stage comprising a closed optical cavity defined in part by a partially reflecting optical element through which the seed laser oscillator output light beam is injected and through which the laser system output is transmitted, the partially reflecting optical element being a single piece and comprising portions that are angled relative to each other; selecting a differential timing between an electrical discharge between a pair of electrodes in the first laser chamber and a pair of electrodes in the second laser chamber to thereby maintain amplified spontaneous emission below a selected limit and the pulse energy of the laser system output light beam of pulses essentially constant; and actively tuning the bandwidth of the pulses of the seed laser output light beam of pulses, wherein tuning the bandwidth comprises adjusting an interaction of a pulse wavefront with a bandwidth selection optic in a line narrowing module of the seed laser oscillator.