Broadband, millimeter-wave antireflection coatings for large-format, cryogenic aluminum oxide optics
Abstract
We present two prescriptions for broadband (~77 - 252 GHz), millimeter-wave antireflection coatings for cryogenic, sintered polycrystalline aluminum oxide optics: one for large-format (700 mm diameter) planar and plano-convex elements, the other for densely packed arrays of quasi-optical elements, in our case 5 mm diameter half-spheres (called "lenslets"). The coatings comprise three layers of commercially-available, polytetrafluoroethylene-based, dielectric sheet material. The lenslet coating is molded to fit the 150 mm diameter arrays directly while the large-diameter lenses are coated using a tiled approach. We review the fabrication processes for both prescriptions then discuss laboratory measurements of their transmittance and reflectance. In addition, we present the inferred refractive indices and loss tangents for the coating materials and the aluminum oxide substrate. We find that at 150 GHz and 300 K the large-format coating sample achieves (97 +/- 2)% transmittance and the lenslet coating sample achieves (94 +/- 3)% transmittance.
Keywords
Cite
@article{arxiv.1912.04272,
title = {Broadband, millimeter-wave antireflection coatings for large-format, cryogenic aluminum oxide optics},
author = {A. Nadolski and J. D. Vieira and J. A. Sobrin and A. M. Kofman and P. A. R. Ade and Z. Ahmed and A. J. Anderson and J. S. Avva and R. Basu Thakur and A. N. Bender and B. A. Benson and L. Bryant and J. E. Carlstrom and F. W. Carter and T. W. Cecil and C. L. Chang and J. R. Cheshire and G. E. Chesmore and J. F. Cliche and A. Cukierman and T. de Haan and M. Dierickx and J. Ding and D. Dutcher and W. Everett and J. Farwick and K. R. Ferguson and L. Florez and A. Foster and J. Fu and J. Gallicchio and A. E. Gambrel and R. W. Gardner and J. C. Groh and S. Guns and R. Guyser and N. W. Halverson and A. H. Harke-Hosemann and N. L. Harrington and R. J. Harris and J. W. Henning and W. L. Holzapfel and D. Howe and N. Huang and K. D. Irwin and O. Jeong and M. Jonas and A. Jones and M. Korman and J. Kovac and D. L. Kubik and S. Kuhlmann and C. -L. Kuo and A. T. Lee and A. E. Lowitz and J. McMahon and J. Meier and S. S. Meyer and D. Michalik and J. Montgomery and T. Natoli and H. Nguyen and G. I. Noble and V. Novosad and S. Padin and Z. Pan and P. Paschos and J. Pearson and C. M. Po sada and W. Quan and A. Rahlin and D. Riebel and J. E. Ruhl and J. T. Sayre and E. Shirokoff and G. Smecher and A. A. Stark and J. Stephen and K. T. Story and A. Suzuki and C. Tandoi and K. L. Thompson and C. Tucker and K. Vanderlinde and G. Wang and N. Whitehorn and V. Yefremenko and K. W. Yoon and M. R. Young},
journal= {arXiv preprint arXiv:1912.04272},
year = {2020}
}
Comments
19 pages, 11 figures; submitted 05 Dec 2019, accepted 26 Feb 2020