基于光学薄膜与环境因素的耦合过程及激光与光学薄膜相互作用的热力损伤过程，分析了真空环境下光学薄膜激光损伤的本征机制。研究显示，真空环境下水的解析引起了电子束沉积的多孔薄膜孔隙率的释放，使得电子束沉积的多孔薄膜折射率及热导率降低，最终导致了薄膜热力损伤过程的加剧，导致了电子束沉积的多孔薄膜在真空环境下损伤阈值极大地降低。

利用1-on-1损伤测试方法, 比较研究了电子束沉积制备的几种薄膜在真空、大气环境下的损伤特性, 并对真空环境与大气环境损伤的差异进行了分析。研究结果显示:真空环境下的损伤阈值明显低于大气环境下的损伤阈值, 真空环境下的破斑形貌也与大气环境下的破斑形貌有显著差异。气体热传导差异不是真空环境与空气环境下损伤差异的原因。由水的解吸而引起膜层在真空环境中张应力的增大及真空环境中激光辐照过程中产生的非化学计量比缺陷是导致电子束沉积的薄膜真空与大气环境中损伤差异的原因。

An automated damage diagnostic system for collecting plasma flash is developed to diagnose damage in a laser-induced damage threshold (LIDT) test system. Experiment is done to verify the accuracy of this system and analyze the relationship between the plasma signals and the damage morphologies. The results obtained by the system are found to be in excellent agreement with those obtained by the much laborious method of Normaski microscope. Results show that plasma signals above 1 V correspond to the damage morphology of surface discolorations with or without pits in their centers, and plasma signals below or just around 1 V correspond to the damage morphology of pits. The misdiagnosis is attributed to contaminations and air breakdown.

P-polarization high reflectors are deposited by e-beam from hafnia and silica. 1-on-1 and N-on-1 tests at 1064-nm wavelength with P-polarization at 45° incidence are carried out on these samples. Microscope and scanning electron microscope are applied to investigate the damage morphologies in both 1-on-1 and N-on-1 tests. It is found that the laser damage threshold is higher in N-on-1 tests and nodular defect is the main inducement that leads to the damage because nodular ejection with plasma scalding is the typical damage morphology. Similar damage morphology observed in the two tests indicates that the higher laser damage threshold in N-on-1 test is attributed to the mechanical stabilization process of nodular defects, owing to the gradually increased laser fluence radiation. Based on the typical morphology study, some process optimizations are given.

利用1-on-1损伤测试方法,测试了真空和空气、氧气、氮气、氦气环境下在波长为1064 nm处增透膜(ARF)的激光损伤阈值和损伤形貌。结果表明,真空环境下的损伤阈值明显低于大气环境下的损伤阈值,真空环境下的破斑形貌也与大气环境下的破斑形貌有显著差异。在真空环境下存入一定量的氧气、氮气和氦气后薄膜的损伤阈值都得到提高,但存入的气体的种类及气压不同,损伤阈值与破斑形貌也不尽相同。