基于薄膜元件的热力学理论, 建立了强激光连续辐照下薄膜元件的热分析模型, 模拟了薄膜元件表面杂质吸热后向周围薄膜进行热传递的过程, 并讨论了表面洁净度等级和杂质尺寸对薄膜元件热应力损伤的影响。研究结果表明: 强激光连续辐照下, 表面杂质会吸收激光能量产生较大的温升, 激光辐照时间越长, 功率密度越大, 杂质的温升也越大; 吸热后, 达到熔点的杂质和未达到熔点的杂质分别通过热传导和热辐射的方式向周围薄膜传递热量, 通过热传导作用在薄膜元件表面引起的温升明显高于热辐射作用引起的; 杂质向周围薄膜传递热量后会在薄膜元件上产生非均匀的温度梯度, 进而产生热应力, 热应力随着温度梯度的增加而增大, 且处于一定尺寸范围内的杂质, 更容易诱导薄膜元件热应力损伤; 此外, 薄膜元件的表面洁净度等级越高, 杂质粒子的数目越多, 越易于造成薄膜元件的热应力损伤。

Based on the thermodynamic theory of thin-film components, the thermal analysis model of thin-film components continuously radiated by high-power lasers is built up. On this basis, the heat transferring process of the thin-film components from impurities to their surrounding thin-film after the surface impurities absorbing heat is simulated, and the influences of surface cleanliness level and the impurity size on the thermal stress damage of the thin-film components are discussed. The results show that, under the continuous radiation of high-power lasers, the laser-energy-absorption of surface impurities gives rise to the relatively high increase of temperature. And the longer the laser irradiation time and the bigger the power density, the more the temperature of the impurities increases. After absorbing heat, the impurities with and without the reaching of melting points transfer heat to their surrounding thin film by the thermal-conduction and thermal-radiation ways, respectively. The temperature rise of the surface of thin-film components caused by thermal-conduction is obviously higher than that by thermal-radiation. Furthermore, the heat-transfer from impurities to surrounding thin-film results in a non-uniform temperature gradient, which further causes the thermal stress. The thermal stress increases with the increase of the temperature gradient, and the thermal stress damage is more likely to happen if the surface impurities localize within a certain range. In addition, the higher the surface cleanliness level of thin-film components and the more the number of impurities, the more easily the thin-film components are damaged.