Active frequency stabilization of a 20-watt CO2laser with etalon wavelength selection

An active laser frequency stabilization scheme involving the use of an internally vibrated laser mirror has been successfully used to stabilize the output of a two-meter long, sealed-off CO2laser operating at powers greater than 20 watts. Long-term frequency variations in the laser were reduced from a free-running stability of about 4 parts in 10⁷to a peak variation of 1 part in 10⁸by this electronic technique. Heterodyne beat frequency measurements were used to obtain the data. The laser short-term stability was improved by hermetically sealing the region between the GaAs Brewster windows and the laser mirrors.