Appl Opt. 2023 Feb 20;62(6):1628-1634. doi: 10.1364/AO.478048.
We present a broadband plasma spray anti-reflection (AR) coating technology for millimeter-wave astrophysics experiments with large-format, cryogenic optics. By plasma spraying alumina- and silica-based powders, we have produced coatings of tunable index of refraction and thickness, low loss, and coefficient of thermal expansion matched to alumina substrates. We demonstrate two-layer AR coatings on alumina with reflection below 5% over 82% and 69% fractional bandwidths for 90/150 and 220/280 GHz passband designs, respectively, and band-averaged absorption loss reduced to ∼1 at 100 K for both AR coatings. We describe the design, tolerance, fabrication process, and optical measurements of these AR coatings.
我们提出了一种宽带等离子喷涂抗反射（AR）涂层技术，用于具有大尺寸、低温光学器件的毫米波天体物理实验。通过等离子喷涂氧化铝和二氧化硅基粉末，我们已经制备出了具有可调折射率和厚度、低损耗和与氧化铝衬底相匹配的热膨胀系数的涂层。我们在氧化铝上展示了两层 AR 涂层，对于 90/150GHz 和 220/280GHz 通带设计，其反射率分别低于 5%，且在 82%和 69%的分数带宽内，两种 AR 涂层在 100K 时的平均吸收损耗均降低到约 1。我们描述了这些 AR 涂层的设计、公差、制造工艺和光学测量。
