Controlling stray light at millimeter wavelengths requires special optical design and selection of absorptive materials that should be compatible with cryogenic operating environments. While a wide selection of absorptive materials exists, these typically exhibit high indices of refraction and reflect/scatter a significant fraction of light before absorption. For many lower index materials such as commercial microwave absorbers, their applications in cryogenic environments are challenging. In this paper, we present a new tool to control stray light: metamaterial microwave absorber tiles. These tiles comprise an outer metamaterial layer that approximates a lossy gradient index anti-reflection coating. They are fabricated via injection molding commercially available carbon-loaded polyurethane (25% by mass). The injection molding technology enables mass production at low cost. The design of these tiles is presented, along with thermal tests to 1 K. Room temperature optical measurements verify their control of reflectance to less than 1% up to 65∘ angles of incidence, and control of wide angle scattering below 0.01%. The dielectric properties of the bulk carbon-loaded material used in the tiles is also measured at different temperatures, confirming that the material maintains similar dielectric properties down to 3 K.
Xu, Z., Chesmore, G., Adachi, S., Ali, A., Bazarko, A., Coppi, G., et al. (2021). The Simons Observatory: metamaterial microwave absorber and its cryogenic applications. APPLIED OPTICS, 60(4), 864-874.
|Citazione:||Xu, Z., Chesmore, G., Adachi, S., Ali, A., Bazarko, A., Coppi, G., et al. (2021). The Simons Observatory: metamaterial microwave absorber and its cryogenic applications. APPLIED OPTICS, 60(4), 864-874.|
|Tipo:||Articolo in rivista - Articolo scientifico|
|Carattere della pubblicazione:||Scientifica|
|Presenza di un coautore afferente ad Istituzioni straniere:||Si|
|Titolo:||The Simons Observatory: metamaterial microwave absorber and its cryogenic applications|
|Autori:||Xu, Z; Chesmore, G; Adachi, S; Ali, A; Bazarko, A; Coppi, G; Devlin, M; Devlin, T; Dicker, S; Gallardo, P; Golec, J; Gudmundsson, J; Harrington, K; Hattori, M; Kofman, A; Kiuchi, K; Kusaka, A; Limon, M; Matsuda, F; McMahon, J; Nati, F; Niemack, M; Suzuki, A; Teply, G; Thornton, R; Wollack, E; Zannoni, M; Zhu, N|
|Data di pubblicazione:||2021|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1364/AO.411711|
|Appare nelle tipologie:||01 - Articolo su rivista|