Efficient algorithms for optimising the optical performance of profiled smooth walled horns for future CMB and Far-IR missions
Efficient algorithms for optimising the optical performance of profiled smooth walled horns for future CMB and Far-IR missions
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用于优化未来 CMB 和远红外任务的异形光滑壁喇叭光学性能的高效算法
DOI：
10.1117/12.2056336
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
P. Huggard
中科院分区：
文献类型：
--
作者：
D. McCarthy;N. Trappe;J. Murphy;C. O'sullivan;M. Gradziel;S. Doherty;C. Bracken;N. Tynan;A. Polegre;P. Huggard
远红外天文观测对于研究宇宙微波背景 (CMB) 辐射以及行星、恒星和星系的形成和演化至关重要。就太空望远镜接收器而言，波纹喇叭天线馈源具有将远红外信号耦合到安装在波导或腔结构中的探测器的强大传统。例如，在普朗克卫星中，此类天线馈电已在用于观测 CMB 的单模通道和针对前景源检测而优化的多模通道中得到利用。着眼于未来太空任务的需求，显然大型阵列需要开发用于优化和简化喇叭天线结构的新技术解决方案。喇叭天线将继续为 CMB 极化实验提供出色的波束和极化特性控制，满足大型阵列中低旁瓣电平、对称性和低交叉极化的严格要求。类似地，对于远红外系统，提出了多模喇叭和波导腔结构来增强腔耦合测辐射热计的弱信号的光学耦合。在本文中，我们提出了一种计算有效的方法来建模和优化喇叭特性。我们研究了光滑壁喇叭，其光学性能与传统上用于 CMB 测量的波纹喇叭相同。我们讨论了喇叭优化过程和可用于最大化指标参数性能（例如低交叉极化或高高斯性）的算法。由该设计过程产生的单模喇叭已在 W 频段构建并进行了实验验证。本文介绍了测量活动的结果，并将其与模拟结果进行了比较，结果表明，同向极化和交叉极化辐射方向图高度一致，而集成交叉极化功率水平较低。对于未来使用波导有界辐射热测量计和吸收器的远红外接收器，积分腔内波导结构和吸收器位置的优化对于最大化耦合性能至关重要，特别是对于多模系统。我们概述了在焦平面阵列中使用多模喇叭的好处，并说明了与多模方法相关的增加的光学灵敏度，该方法可以针对与特定入射光束的耦合进行优化。
Astronomical observations in the far-infrared are critical for investigation of cosmic microwave background (CMB) radiation and the formation and evolution of planets, stars and galaxies. In the case of space telescope receivers, a strong heritage exists for corrugated horn antenna feeds to couple the far-infrared signals to the detectors mounted in a waveguide or cavity structure. Such antenna feeds have been utilized, for example, in the Planck satellite in both single-mode channels for the observation of the CMB and the multi-mode channels optimized for the detection of foreground sources. Looking to the demands of the future space missions, it is clear that the development of new technology solutions for the optimization and simplification of horn antenna structures will be required for large arrays. Horn antennas will continue to offer excellent control of beam and polarization properties for CMB polarisation experiments satisfying stringent requirements on low sidelobe levels, symmetry, and low cross polarization in large arrays. Similarly for far infrared systems, multi-mode horn and waveguide cavity structures are proposed to enhance optical coupling of weak signals for cavity coupled bolometers. In this paper we present a computationally efficient approach for modelling and optimising horn character-istics. We investigate smooth-walled horns that have an equivalent optical performance to that of corrugated horns traditionally used for CMB measurements. We discuss the horn optimisation process and the algorithms available to maximise performance of a merit parameter such as low cross polarisation or high Gaussicity. A single moded horn resulting from this design process has been constructed and experimentally verified in the W band. The results of the measurement campaign are presented in this paper and compared to the simulated results, showing a high level of agreement in co and cross polarisation radiation patterns, with low levels of integrated cross polar power. For future Far IR receivers using waveguide bounded bolometers and absorbers, an optimisation of the waveg-uide structures and absorber location within the integrating cavity is critical to maximise coupling performance particularly for multimoded systems. We outline the benefit of using multi-moded horns in focal plane arrays and illustrate the increased optical sensitivity associated with a many-moded approach, which may be optimized for coupling to particular incident beams.