摘要 |
Gas laser apparatus comprises a cavity 10 containing a gaseous active medium, and discharge electrodes 11 and 12 between which a potential difference may be applied to produce an electric pumping discharge in the active medium. A reservoir 17 communicates with the cavity to form a sealed enclosure containing the active medium and volume control means 19 are contained in the reservoir 17 to vary the pressure of the gaseous active medium in the cavity. |