为了研究大功率CO2激光发射过程中输出窗口吸收激光能量产生热性能变化的问题, 建立了输出窗口传热学和结构力学耦合非稳态模型, 通过对模型进行有限元分析得到表征输出窗口变化的温度、热变形和热应力等参数分布。首先, 针对大功率CO2激光特点, 讨论了输出窗口材料GaAs和ZnSe的物理特性。然后, 基于10 kW级大功率CO2激光器光学谐振腔结构和输出窗口材料物理特性, 建立了输出窗口传热学和结构力学的有限元模型。最后, 利用COMSOL软件对该模型进行求解, 得到以GaAs和ZnSe为材料的输出窗口的温度、热变形和热应力等参数分布, 并对比分析不同窗口材料对参数的影响。研究表明: 在10 kW级激光作用下, ZnSe窗口温升小于GaAs窗口; 两种输出窗口产生μm量级热变形; 由于GaAs材料的热导率高, GaAs窗口的热变形和热应力分布更为均匀。

In order to study the thermal characteristic of output window during the working process of high power CO2 laser, a time-dependent model coupled with heat transfer and structure mechanic was established to calculate the distribution of temperature, thermal deformation and thermal stress. First, the physics characteristic of output window materials was discussed. Then, based on the resonant cavity structure of 10 kW TEA CO2 laser and the physics characteristic of output windows, a heat transfer and structure mechanic model was established. Finally, COMSOL finite element software was used to calculate the distribution of temperature, thermal deformation and thermal stress. The influence of different materials of output window on parameters was analyzed. The results indicate that the temperature rise of ZnSe output window is less than the GaAs output window when the output power is consistent for both materials; the deformation of output windows is in the range of μm dimension under the 10 kW laser power condition; the distribution of thermal deformation and thermal stress is more even in GaAs output window for its high heat transfer coefficient.