Plastic Laminate Antireflective Coatings for Millimeter-wave Optics in BICEP Array
Abstract
The BICEP/Keck series of experiments target the Cosmic Microwave Background at degree-scale resolution from the South Pole. Over the next few years, the "Stage-3" BICEP Array (BA) telescope will improve the program's frequency coverage and sensitivity to primordial B-mode polarization by an order of magnitude. The first receiver in the array, BA1, began observing at 30/40 GHz in early 2020. The next two receivers, BA2 and BA3, are currently being assembled and will map the southern sky at frequencies ranging from 95 GHz to 150 GHz. Common to all BA receivers is a refractive, on-axis, cryogenic optical design that focuses microwave radiation onto a focal plane populated with antenna-coupled bolometers. High-performance antireflective coatings up to 760 mm in aperture are needed for each element in the optical chain, and must withstand repeated thermal cycles down to 4 K. Here we present the design and fabrication of the 30/40 GHz anti-reflection coatings for the recently deployed BA1 receiver, then discuss laboratory measurements of their reflectance. We review the lamination method for these single- and dual-layer plastic coatings with indices matched to various polyethylene, nylon and alumina optics. We also describe ongoing efforts to optimize coatings for the next BA cryostats, which may inform technological choices for future Small-Aperture Telescopes of the CMB "Stage 4" experiment.
Keywords
Cite
@article{arxiv.2111.14751,
title = {Plastic Laminate Antireflective Coatings for Millimeter-wave Optics in BICEP Array},
author = {Marion Dierickx and P. A. R. Ade and Zeeshan Ahmed and Mandana Amiri and Denis Barkats and Ritoban Basu Thakur and Colin A. Bischoff and Dominic Beck and James J. Bock and Victor Buza and James R. Cheshire and Jake Connors and James Cornelison and Michael Crumrine and Ari Jozef Cukierman and Edward Denison and Lionel Duband and Miranda Eiben and Sofia Fatigoni and Jeff P. Filippini and Christos Giannakopoulos and Neil Goeckner-Wald and David Goldfinger and James A. Grayson and Paul Grimes and Grantland Hall and George Halal and Mark Halpern and Emma Hand and Sam A. Harrison and Shawn Henderson and Sergi Hildebrandt and Gene C. Hilton and Johannes Hubmayr and Howard Hui and Kent D. Irwin and Jae Hwan Kang and Kirit S. Karkare and Sinan Kefeli and J. M. Kovac and Chao-Lin Kuo and King Lau and Erik M. Leitch and Amber Lennox and K and . G. Megerian and Lorenzo Minutolo and Lorenzo Moncelsi and Yuka Nakato and Toshiya Namikawa and H. T. Nguyen and Roger O'brient and Steven Palladino and Matthew Petroff and Nathan Precup and Thomas Prouve and Clement Pryke and Benjamin Racine and Carl D. Reintsema and Destiny Santalucia and Alessandro Schillaci and Benjamin Schmitt and Baibhav Singari and Ahmed Soliman and Tyler St Germaine and Bryan Steinbach and Rashmi Sudiwala and Keith L. Thompson and Carole Tucker and Anthony D. Turner and Caterina Umiltà and Clara Verges and Abigail G. Vieregg and Albert Wandui and Alexis C. Weber and Don Wiebe and Justin Willmert and Wai Ling K. Wu and Hung-I Yang and Ki Won Yoon and Edward Young and Cyndia Yu and Lingzhen Zeng and Cheng Zhang and Silvia Zhang},
journal= {arXiv preprint arXiv:2111.14751},
year = {2023}
}
Comments
8 pages, 4 figures. Submitted to Journal of Low Temperature Physics