Numerical Simulation Study On Thermal Stress Damage In Double Anti-reflection Film Irradiated By The Repetition Frequency Long Pulse Laser

The interaction between laser and material is very important in the material processing,mechanical manufacturing, optico-electronic imaging system, and so on. And the interaction between the optical anti-reflection thin film and the repetition frequency laser is especially important. In this paper, the thermal stress damage of optical thin film materials irradiated by the repetition frequency long pulse laser is numerically simulated and analyzed.In this paper, the physical model of single layer thin film material(Al2O3/ K9) and double-layer thin film material(Si O2/Al2O3/K9) was established by the repetition frequency long pulse laser irradiation,using the finite element algorithm to solve the corresponding equation of heat conduction and thermal stress, having the thermal stress field distribution inside the material.The numerical results show that, Single layer thin film:when the temperature cool dow, the residual ring thermal stress move along the radial, under the condition of low frequency, the thermal stress damage is the basement first, after then is the thin film. Double layer thin film: From the analysis on the laser parameters, that the temperature of film decreases with the increase of the pulse width when the duty ratio of pulse laser is the same; From the analysis on the thermal stress damage of film system, the ring tensile stress taken place in the SiO2 film damage phenomenon firstly, substrate of K9 occurred the ring tensile damage phenomenon secondly, thirdly K9 substrate began to melt,SiO2 occurred to melt lastly. The results of this paper can be used to analyze and reveal the interaction mechanism between laser and thin films systematically and provide a theoretical basis for the design of optical thin film and technology of hardening thin film against laser.