使用脉宽约10 ns的Nd:YAG激光器,研究低加工缺陷条件下K9光学玻璃在单激光脉冲作用下的损伤形貌.利用软边光阑加长程衍射的方法实现光斑整形,利用微分干涉光学显微镜和扫描电镜对样品前后表面的损伤形貌进行观察和成像,对比研究了K9光学玻璃前后表面的损伤形貌,分析了损伤机制.研究结果显示:在红外纳秒激光辐照下,加工缺陷是K9光学玻璃产生初始损伤的主要诱因;前表面的损伤主要表现为微坑及高温等离子体产生的冲蚀变色和表面微裂纹;后表面出现了均匀的亚波长周期性光栅结构,这种周期性结构是后表面损伤增长的主要诱因.%The lifetime of a laser optics is limited by laser-induced damage and subsequent growth of laser initiated damage area. Morphology and growth of laser-induced damage on polished K9 glass surface and inside of the material have been measured after single-shot laser irradiation at 1 064 nm wavelength and approximately 10 ns pulse duration. Differential interference contrast (DIC) optical microscopy, SEM are used for imaging the damage sites. All of the observed damage is concentrated on the optics surface, and the output surface damage is more visible and serious than input surface. For input surface, plasma produced by laser pulse shields the material and reduces material destruction, symmetrical craterlet and microcrack is produced by ablation effect and laser-supported detonation wave(LSDW). For output surface, the interference of incident laser with the reflected laser from rear surface, the absorption zone moves toward the beam and laser energy is deposited inside of the optical material, sub wavelength pe riodic grating microstructure and damage-spot are observed. The damage morphology and damage mechanisms are compared for input and output surface, possible reasons for the observed initiation growth behavior are discussed.
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