论文标题
Qubic VI：低温半波板旋转器，设计和性能
QUBIC VI: cryogenic half wave plate rotator, design and performances
论文作者
论文摘要
通胀重力波B模型极化检测是世界各地现代大角度尺度宇宙微波背景（CMB）实验的最终目标。通过使用不同的方法将这种微弱的极化成分与进入辐射分开的许多地面，气球传播和卫星实验的部署正在进行巨大的努力。使用的技术之一是使用旋转半波板（HWP）和线性偏振器分离和调节偏振组件低残留交叉极化的偏振组件的Stokes占地法。本文介绍了Qubic Stokes Polarimeter突出显示其设计功能和性能。这些设备的常见系统是产生与旋转同步的大型虚假信号，并且与光学元素的发射率成正比。 Qubic Stokes偏振仪的一个关键特征是在低温温度下运行，以最大程度地减少这种不需要的成分。在低温下有效地移动这个大型光学元素是一个巨大的工程挑战，以减少摩擦力耗散。在设计阶段给予了很大的关注，以最大程度地减少零件之间的差分热收缩。旋转是由放置在低温恒温器外的步进电动机驱动的，以避免在低温温度下进行热负荷耗散。这项工作中提出的测试和结果表明，Qubic极性计可以轻松地在定位时仅使用步进电动机精度和光学绝对编码器来达到低于0.1°的精度。在第二个低温阶段（〜8 K），旋转仅引起少量MK额外的功率负载。
Inflation Gravity Waves B-Modes polarization detection is the ultimate goal of modern large angular scale cosmic microwave background (CMB) experiments around the world. A big effort is undergoing with the deployment of many ground-based, balloon-borne and satellite experiments using different methods to separate this faint polarized component from the incoming radiation. One of the largely used technique is the Stokes Polarimetry that uses a rotating half-wave plate (HWP) and a linear polarizer to separate and modulate the polarization components with low residual cross-polarization. This paper describes the QUBIC Stokes Polarimeter highlighting its design features and its performances. A common systematic with these devices is the generation of large spurious signals synchronous with the rotation and proportional to the emissivity of the optical elements. A key feature of the QUBIC Stokes Polarimeter is to operate at cryogenic temperature in order to minimize this unwanted component. Moving efficiently this large optical element at low temperature constitutes a big engineering challenge in order to reduce friction power dissipation. Big attention has been given during the designing phase to minimize the differential thermal contractions between parts. The rotation is driven by a stepper motor placed outside the cryostat to avoid thermal load dissipation at cryogenic temperature. The tests and the results presented in this work show that the QUBIC polarimeter can easily achieve a precision below 0.1° in positioning simply using the stepper motor precision and the optical absolute encoder. The rotation induces only few mK of extra power load on the second cryogenic stage (~ 8 K).
