Plastic Laminate Antireflective Coatings for Millimeter-wave Optics in BICEP Array
Creators: name: Dierickx, Marion
name: Ade, P. A. R.
name: Ahmed, Zeeshan
name: Amiri, Mandana
name: Barkats, Denis
name: Thakur, Ritoban Basu
name: Bischoff, Colin A.
name: Beck, Dominic
name: Bock, James J.
name: Buza, Victor
name: Cheshire, James R.
name: Connors, Jake
name: Cornelison, James
name: Crumrine, Michael
name: Cukierman, Ari Jozef
name: Denison, Edward
name: Duband, Lionel
name: Eiben, Miranda
name: Fatigoni, Sofia
name: Filippini, Jeff P.
name: Giannakopoulos, Christos
name: Goeckner-Wald, Neil
name: Goldfinger, David
name: Grayson, James A.
name: Grimes, Paul
name: Hall, Grantland
name: Halal, George
name: Halpern, Mark
name: Hand, Emma
name: Harrison, Sam A.
name: Henderson, Shawn
name: Hildebrandt, Sergi
name: Hilton, Gene C.
name: Hubmayr, Johannes
name: Hui, Howard
name: Irwin, Kent D.
name: Kang, Jae Hwan
name: Karkare, Kirit S.
name: Kefeli, Sinan
name: Kovac, J. M.
name: Kuo, Chao-Lin
name: Lau, King
name: Leitch, Erik M.
name: Lennox, Amber
name: K
name: Megerian, . G.
name: Minutolo, Lorenzo
name: Moncelsi, Lorenzo
name: Nakato, Yuka
name: Namikawa, Toshiya
name: Nguyen, H. T.
name: O'brient, Roger
name: Palladino, Steven
name: Petroff, Matthew
name: Precup, Nathan
name: Prouve, Thomas
name: Pryke, Clement
name: Racine, Benjamin
name: Reintsema, Carl D.
name: Santalucia, Destiny
name: Schillaci, Alessandro
name: Schmitt, Benjamin
name: Singari, Baibhav
name: Soliman, Ahmed
name: Germaine, Tyler St
name: Steinbach, Bryan
name: Sudiwala, Rashmi
name: Thompson, Keith L.
name: Tucker, Carole
name: Turner, Anthony D.
name: Umiltà, Caterina
name: Verges, Clara
name: Vieregg, Abigail G.
name: Wandui, Albert
name: Weber, Alexis C.
name: Wiebe, Don
name: Willmert, Justin
name: Wu, Wai Ling K.
name: Yang, Hung-I
name: Yoon, Ki Won
name: Young, Edward
name: Yu, Cyndia
name: Zeng, Lingzhen
name: Zhang, Cheng
name: Zhang, Silvia
Publisher: name: arXiv
Year: 2021
Subjects: subject: Instrumentation and Methods for Astrophysics (astro-ph.IM)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: 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.
description: 8 pages, 4 figures. Submitted to Journal of Low Temperature Physics