AN INDUSTRIAL QUALITY AUTOMATIC RESONATOR ALIGNMENT SYSTEM FOR A 20 KW CO2-LASER

A limiting feature in high-power laser technology which has surfaced i n recent years is alignment instability induced by thermally generated distortions of the optical hardware and phase perturbations of the ga in media under elevated power loading. In an effort to ameliorate thes e problems, a study was initiated to ascertain the feasibility of util izing a feedback control system both to monitor and align the resonato r optics of a multikilowatt laser; thereby actively preserving optimum mode quality. This papers summarizes the results of this project and outlines the basic approach used to construct a controller which accom plishes fully automatic alignment of both mirrors in an unstable reson ator for a 20 kW CO2 machine. A mathematical model of the control syst em is presented along with a description of the principles of operatio n. Data are provided to document the major improvement in device perfo rmance achievable using this automatic alignment controller concept.