Laser-induced pit formation in UV-antireflective coatings
Laser-induced pit formation in UV-antireflective coatings
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DOI：
10.1117/12.2500338
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发表时间：
2018-11
期刊：
影响因子：
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通讯作者：
S. Paschel;I. Balasa;L. Jensen;X. Cheng;Z. Wang;D. Ristau
中科院分区：
文献类型：
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作者：
S. Paschel;I. Balasa;L. Jensen;X. Cheng;Z. Wang;D. Ristau
以前的研究表明，纳米级的缺陷，可以导致形成亚微米的火山口，如果位于一个相对较小的厚度涂层。由于尺寸小，在在线和离线损伤检测中检测这种损伤具有挑战性，因此可能导致被测光学部件的LIDT的高估。然而，这些纳米孔的光学性质和对灾难性损伤的影响的影响，在过去没有详细研究。为了研究纳米孔，光学性能和灾难性损伤之间的相关性，与AR涂层的样品通过离子束溅射（IBS）制造，并通过LIDT光栅扫描在纳秒制度在355 nm下测试其耐激光性。纳米孔的生成和形态变化进行了监测不同的脉冲数和依赖于起始注量。除了如ISO 21254所规定的在微分干涉对比（DIC）模式下用光学显微镜进行检查之外，使用替代检查方法（例如，暗场显微镜和扫描电子显微镜（SEM））来检测纳米孔。损伤测试表明，纳米孔很少出现在标准AR涂层中，并且与LIDT仅具有很小的相关性。观察到的典型损伤形态包括微米级的坑，其在大的能量密度范围内具有稳定的尺寸，并且在重复照射后没有生长。
Previous studies have shown that nanometer scale defects can lead to the formation of submicrometer craters, if located in coatings with a relatively small thickness. Due to the small size, such damages are challenging to detect in the online and offline damage detection and may therefore lead to an overestimation of the LIDT for the tested optical component. However, the influence of these nanopits on the optical properties and the impact on the initiation of catastrophic damage was not investigated in detail in the past. In order to study the correlation between nanopits, optical properties and catastrophic damage, samples with an AR-coating were fabricated by means of ion beam sputtering (IBS) and tested for their laser resistance by LIDT raster scans in the nanosecond regime at 355 nm. The generation and morphology changes of the nanopits were monitored for different pulse numbers and in dependence of the starting fluence. In addition to the inspection with an optical microscope in differential interference contrast (DIC) mode as prescribed by ISO 21254, alternative inspection methods, for example, dark field microscopy and scanning electron microscopy (SEM), were used to detect the nanopits. The damage test revealed that nanopits occur rarely in standard AR-coatings and possess only a small relevance for the LIDT. The typical damage morphology observed consisted of micrometer-sized pits which exhibited a stable size over a large fluence range and no growth after repeated irradiation.