Optics and broadband antireflection coatings for the BA4-90/150 receiver

Polish, A. R., Ade, P. A. R. ORCID: https://orcid.org/0000-0002-5127-0401, Ahmed, Z., Amiri, M., Barkats, D., Thakur, R. Basu, Bischoff, C. A., Beck, D., Bock, J. J., Buza, V., Cantrall, B., Cheshire, J. R., Connors, J., Cornelison, J., Crumrine, M., Cukierman, A. J., Denison, E., Duband, L., Echter, M., Eiben, M., Elwood, B. D., Fatigoni, S., Filippini, J. P., Fortes, A., Gao, M., Giannakopoulos, C., Goeckner-Wald, N., Goldfinger, D. C., Gratton, S., Grayson, J. A., Greathouse, A., Grimes, P. K., Halpern, M., Henderson, S., Hoang, T. D., Hubmayr, J., Hui, H., Irwin, K. D., Poza, M. Izquierdo, Kang, J. H., Karkare, K. S., Kefeli, S., Kovac, J. M., Kuo, C., Lasko, K., Lau, K., Lautzenhiser, M., Liu, T., Mackey, S., Maher, N., Megerian, K. G., Minutolo, L., Moncelsi, L., Nakato, Y., Nguyen, H. T., O'Brient, R., Paine, S. N., Patel, A., Petroff, M. A., Prouve, T., Pryke, C., Reintsema, C. D., Rioles, P. J., Romand, T., Salatino, M., Schillaci, A., Schmitt, B., Singari, B., Soliman, A., Germaine, T. St., Steiger, A., Steinbach, B., Sudiwala, R. ORCID: https://orcid.org/0000-0003-3240-5304, Thompson, K. L., Tucker, C. ORCID: https://orcid.org/0000-0002-1851-3918, Turner, A. D., Vergès, C., Vieregg, A. G., Wandui, A., Weber, A. C., Willmert, J., Wu, W. L. K., Yang, H., Yu, C., Zeng, L., Zhang, C. and Zhang, S. 2026. Optics and broadband antireflection coatings for the BA4-90/150 receiver. Presented at: SPIE Astronomical Telescopes and Instrumentation, Copenhagen, Denmark, 5-10 July 2026. Proceedings of SPIE. , vol.14156 10.1117/12.3105361

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Abstract

The BICEP Array telescopes search for primordial B-mode polarization from inflationary gravitational waves. This signal is exceedingly faint, demanding excellent map depth and systematics control. The new BA4-90/150 receiver introduces a wide 80–169 GHz dichroic band, requiring upgrades throughout the optics chain to reduce loss, reflections, and thermal loading. We developed improved anti-reflection coatings for the HMPE window, HDPE lenses, and nylon infrared filter, extending previous technology to span more than an octave of bandwidth. The thermal filtering scheme and several mechanical elements were also updated to further suppress optical loss, reflections, and beam truncation. We summarize the updated optical design, material choices, expected thermal and spectral performance, and laboratory results from coated prototypes. These results establish the readiness of the optics and AR-coating approach for BA4-90/150 and provide a foundation for future wide-band CMB instruments.

Item Type:	Conference or Workshop Item - published (Paper)
Date Type:	Publication
Status:	Published
Schools:	Schools > Physical, Chemical & Environmental Sciences Schools > Physics and Astronomy
ISSN:	0277-786X
Last Modified:	27 Aug 2026 12:00
URI:	https://orca.cardiff.ac.uk/id/eprint/189208

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