表面抛光可能给K9基片带来额外的杂质和吸收, 分离K9基片的表面吸收率与体吸收率有助于改进基片的加工质量和抛光工艺, 对抗损伤能力研究具有重要意义。分析了激光量热法测量弱吸收的原理, 采用符合ISO 11551要求的激光量热计测量K9基片的弱吸收。对相同工艺抛光的不同厚度K9基片进行了弱吸收表征, 实验发现K9基片的弱吸收随着厚度增加近似线性增大。推导了表面吸收率和体吸收率的计算式, 实验得出本样品的表面吸收率为1.21×10-5, 体吸收率远大于表面吸收率, 体吸收系数为1.72×10-3/cm。实验结果显示所用K9样品的吸收主要来自于材料本身, 改善抛光工艺对降低其吸收率作用不大。

Absorption might be increased due to the impurities introduced by polishing. To differentiate the surface absorptance and bulk absorptance of K9 substrates is of great importance. It is significant for the research of laser resistance, and helpful for the improvement of producing and polishing technique of K9. In this paper, the principle of laser calorimetry was analyzed, and a laser calorimeter according to ISO 11551 was applied to measure K9 substrates. The weak absorptance of K9 substrates with same polishing technique and different thicknesses was characterized. It is found that the absorptance increases nearly linearly with the increasing of thickness. The equation to calculate the surface and bulk absorptances was analyzed, and the surface absorptance in this experiment was 1.21×10-5, while the bulk absorptance coefficient was 1.72×10-3/cm which was much greater than the former. The conclusion is made that the K9 absorption is mainly caused by the material itself, and improving polishing technique cannot do much to decrease its absorption.