Damage morphology change condition and thermal accumulation effect on high-reflection coatings at 1064nm

The damage conversion behavior of high-reflection coatings under multiple shot of 1064nm nanosecond pulse laser has been investigated. The mechanism of initiation and evolution law of multi-shot damage has been revealed by use of surface profiler and focus ion beam with SEM. The scald damage tends to become delaminate damage under some certain condition. Huge experiments supports that this morphology change condition has a close connection with scald initial fluence, scald size, subsequent fluence and shot number. The relationship among these factors is for the first time achieved to offer the "safety lines" for components. The thermal accumulation effect on the decline of damage threshold under multi-shot has been studied in theory and verified experimentally. In addition, a theory-based formula is used to fit the experiment data for further prediction of thin film life-time.