A frequency stabilized waveguide CO2-laser for photoacoustic spectroscopy of gases

A theoretical model of a waveguide CO2-laser was made to optimize the dimensions of the waveguide tube and resonator, i.e., to obtain the best mode structure while maximizing the output power. The results were used to design and build the laser itself around a quartz waveguide tube of 25.5 cm and 3 mm inner diameter. A simple, low-cost, and efficient VMOS based current stabilization was applied, which stabilized the current to within ±0.5 %. The working laser frequency selection and/or frequency stabilization was controlled by a piezo micro-positioner, which was coupled with an output power meter via a PC computer and driven by self-made software developed for the purpose. The experimental test of the laser showed good agreement with the model.