激光辐照下光学薄膜元件温升的有限元分析

Analysis of temperature rise of films at laser irradiation based on finite element method

实验测量了波长1064nm,10kHz高重复频率激光辐照下镀制Ta2O5/SiO2多层膜的K9、石英玻璃、白宝石高反膜元件温升变化。有限元分析的结果与实验结果相一致。用ANSYS程序计算了不同基板、空气对流系数及基板尺寸对激光辐照中心点温度的影响。结果表明:白宝石基片的薄膜元件激光辐照点的温度最低,其次是石英,K9玻璃基片的薄膜元件激光辐照点温度最高。空气对流系数在大光斑或长时间辐照时对激光辐照点温度影响较大,在小光斑或短时间辐照时对激光辐照点温度影响甚微,可忽略不计。基板越厚,基板直径越大,激光辐照中心点温度越低,基板直径比厚度更能影响激光辐照中心点温度变化。

The experiments were performed by measuring the temperature rise of Ta2O5/SiO2 multilayer coatings on the substrate K9,fused silica and sapphire at repetition frequency 10 kHz wavelength 1064nm pulse laser. The results calculated by ANSYS agreed well with the experiment data. The influences of different substrate,cross-ventilation coefficient and size on temperature of center point of films at laser irradiation were calculated by ANSYS. The result indicates that,at the same laser irradiation,the sapphire′s maximal temperature is lower than that of fused silica or K9. The temperature effect of cross-ventilation coefficient is neglectable at small laser facula or little time laser irradiation,but must be considered when large laser facula or long time laser irradiation. The size of substrate also affects the maximal temperature of film under laser irradiation. As the diameter and thickness of substrate are increasing,the maximal temperature of films is increasing accordingly. The temperature effect of substrate diameter is more obvious than that of substrate thickness.