标题： 基于地面CMB望远镜的氧化铝滤光片的原型亚波长结构抗反射涂层 显示英文标题

标题： Prototype sub-wavelength structure anti-reflection coating on alumina filters for ground-based CMB telescopes

摘要： 我们提出了用于红外吸收滤波器的二氧化铝上亚波长抗反射（AR）结构的设计和制造，这些滤波器的通带接近30、125和250 GHz。 这些频段被地面仪器广泛用于测量宇宙微波背景辐射。 这些设计经过调整，以在51%到72%的分数带宽范围内提供2%或更低的反射率，每个主要频带包含两个子频带。 我们使用激光刻蚀制作了类似于二维金字塔阵列的亚波长结构（SWS）。 我们测量了所制备金字塔的形状，并表明对于入射角高达20度的情况，预测的带内平均反射率为2%或更低，与设计相符。 带平均仪器偏振小于$3\times 10^{-3}$。 显示英文摘要

摘要： We present designs and fabrication of sub-wavelength anti-reflection (AR) structures on alumina for infrared absorptive filters with passbands near 30, 125, and 250 GHz. These bands are widely used by ground-based instruments measuring the cosmic microwave background radiation. The designs are tuned to provide reflectance of 2% or less for fractional bandwidths between 51% and 72%, with each of the three primary bands containing two sub-bands. We make the sub-wavelength structures (SWS), which resemble a two-dimensional array of pyramids, using laser ablation. We measure the shapes of the fabricated pyramids and show that for incidence angles up to 20 degrees the predicted in-band average reflectance is 2% or less, in agreement with the design. The band average instrumental polarization is less than $3\times 10^{-3}$.