表面热透镜技术测量3.8μm和2.8μm激光薄膜的微弱吸收

 采用表面热透镜技术，对3.8μm和2.8μm激光辐照下镀制在Si基底上的单层ZnS，YbF₃和YBC薄膜及不同膜系的YbF₃/ ZnS多层分光膜和多层高反膜，以及镀制在CaF₂基底上的增透膜进行了吸收测量，并对3.8μm和2.8μm 激光的测量结果进行了比较分析。实验结果表明，2.8μm波长下的吸收比3.8μm的大得多，两者之间约相差一个量级，测得的多层高反膜YbF₃/ZnS薄膜在的3.8μm处的最低吸收为4.57×10^－4，测量系统的灵敏度约为10^-5。

Thin film weak absorption of 3.8μm and 2.8μm laser measured by surface thermal lensing technique

Using the surface thermal lensing technique, weak absorption of different optical thin films, including the single-layer ZnS and YbF_3 dielectric thin films with different thickness, as well as the different multilayer thin films YbF_3/ZnS deposited on Si, and multilayer anti-reflectivity thin films YbF_3/ZnS deposited on CaF_2 window has been measured. The experimental results of films irradiated by 3.8μm and 2.8μm lasers have been compared and analyzed. The experimental results show that absorption at 2.8μm, is much greater than the one at 3.8μm,and the difference between them is one order of magnitude. The lowest absorption at 3.8μm is 4.57×10~(-4), and the system sensitivity is 10~(-5) level.