20-watt single-frequency CO2laser

A short-term frequency-stabilized, single-frequency, sealed-off CO2laser is described which is capable of emitting 20 watts in a single mode. The technique used to obtain both high power and high frequency stability simultaneously utilizes a master oscillator-power amplifier approach. The oscillator consists of a 3-5 watt, 1-meter long Brewster angle laser. Single wavelength operation is obtained by length tuning the laser. Heterodyne measurements on two oscillator units have indicated short-term stabilities of better than 1:10⁹(30 kHz) in a normal laboratory environment. Instabilities are primarily due to atmospheric pressure fluctuations, airborne vibrations due to laboratory noise and vibrations from the cooling water used with the lasers. Long-term frequency stabilities of about 1:10⁷(3 MHz) have been obtained by thermal control techniques alone. The amplifier required to increase the laser power to 20 watts consists of two dc-operated 2-meter long tubes with Brewster windows. The design and operating characteristics of the laser will be given with up-to-date performance results.