Reacher On Temperature Field Characteristics About K9:SiO2/HfO2Anti-Reflection Film Induced By Long-Pulse Laser

In terms of thermal conductivity, based on the Fourier’s law of heat conduction and combined with thermal equilibrium relationship and Newton’s law of cooling. The thesis has established the target induced by long-pulsed laser thermodynamic model in the ideal case, has analyzed the boundary conditions of the model. On account of the finite difference method, considering the optical field distribution of target radiated by laser, the thesis has solved the equation of temperature field contribution about K9:SiO2/HfO2target irradiated flat-top laser beam. On this basis, a brief discussion of the target’s stress problems caused by the energy absorption and thermal conductivity has been given.Based on the established physical mathematical model of the damage induced by long-pulse laser irradiation for the K9:SiO2/HfO2target. Take no account of the heat exchange between the target and the environment (air convection), between the substrate and film, between films, as well as between film and air. And assuming laser induced damage of the target is only caused by the heat and heat stress. Based on the heat conduction equation, the thesis has studied the characteristics of temperature and thermal stress field of K9glass and K9base coating target induced by the ms pulse laser; has obtained the temperature and the stress field distribution about the laser radiation zone and vicinity at some moments from the radiation beginning to after the end of a period of time, including between the base and adjacent coating, between coatings; has analyzed the important significance of temperature and stress field to study the phenomenon of laser-material interaction.In conclusion, under conditions that the laser energy is slightly greater than the damage threshold of the film material, if the thermal stress of film material generated by the laser energy absorbed is over their stress threshold,it will cause the film to crack or fall off, the damage location in the beam edge of the flat-topped beam; if the stress damage threshold of the film material is relatively higher, the stress of film induced by laser is not enough to crack and stripping before melt, when the temperature caused by the laser rises to melting point, the material will melt.