Research On Laser-induced Damage Threshold Of 10.6μm Optical Coating In TEA CO₂ Laser System

In high power TEA CO2 laser systems, optical coating's performance is a key technical problem which restricts the increase of the laser power and the laser beam quality. Fundamentals of laser-induced damage in high power TEA CO2 laser systems were discussed in this thesis, and laid a strong emphasis on how to improve laser-induced damage threshold of optical coating.Several damage mechanisms of laser-induced damage of coating were discussed. The damage mechanism varying with radiation manner and laser parameters was also analyzed. Introduced several methods of testing damage threshold of coating, both mechanism and method in several threshold test were discussed; the characteristic of different methods was analyzed.Anti-injury coatings in high power TEA CO2 laser systems were designed and manufactured. Several methods of dealing optical coating to improve damage threshold were discussed. Consult idiographic condition, the feasibility of using large area laser spot was proved, the variety of damage threshold under the influence of large area laser spot was also theoretical and experimental studied in detail. The mechanism of damage threshold variety of 10.6μm optical coating under different laser conditioning condition was gained, and the damage threshold of 10.6μm optical coating was successfully improved.The relationship between laser-induced damage thresholds of optical coating and thickness of substrate of optical coating was investigated experimentally. The results show that higher damage threshold could be gained when coatings were on thicker substrate.The variety in characteristic of both oxide and oxide-free optical coatings after ion post-treatment was analyzed; the mechanism of improving laser-induced damage threshold by ion post-treatment was clarified further.