Holographic Coatings for Telescopes

在过去的一年里，物理光学公司(POC)已经成功地制造出了光谱的UV、可见光和非常近红外区域的全息皱纹结构。这些全息反射镜的激光损伤阈值是最好的介质多层膜的5倍，反射率超过99.9%。本研究计划将这种全息皱纹技术推广到1微米到3微米的区域。红外区域的全息记录过程也应该产生超高的损伤阈值，并且很容易扩展到非常大的光学元件。所采用的全息工艺使用低温沉积方法和全息涂层与栅格的集成。这些光栅可以作为光束采样器来输出耦合器。POC的涂层工艺具有制造工艺简单、记录介质的低吸收特性和辐射防护效果好等特点，是民用和军用应用的理想新技术。与现有的涂层技术相比，POC的方法将大大降低结构重量、热负荷和成本，因为它可以应用于轻质基板，如图形-环氧树脂、聚乳酸、铝和超薄玻璃。此外，初步的实验结果表明，该涂层不存在脱色问题。

During the past year, Physical Optics Corporation (POC) has been successful in fabricating holographic rugate structures for the UV, visible, and very near IR regions of the spectrum. These holographic mirrors demonstrated laser damage thresholds which were 5 times better than the best dielectric multilayer coatings, with reflectivities in excess of 99.9%. This research project proposes to extend this holographic rugate technology to the region from 1 um to 3um. The holographic recording process for the IR region should also yield ultra high damage thresholds and be easily scalable to very large optics. The holographic processes employed use low temperature deposition methods and an integration of holographic coatings with gratings. These gratings can be used as beam samplers to output couplers. The potential for a simple fabrication process, low absorption characteristics of the recording medium, and a demonstrated radiation harness make POC'S coating process an ideal new technology for civilian and military applications. POC's approach will greatly reduce structural weight, thermal load and cost compared to existing coating technologies since it can be applied to light-weigh substrates such as graphic-epoxy, mylar, aluminum, and ultra-thin glass. Moreover, initial experimental results have demonstrated that the coating has no degrassing problem.