Development and precision characterisation of broadband anti-reflection-coated mm-wave components

Lyons, Matthew, Hargrave, Peter ORCID: https://orcid.org/0000-0002-3109-6629, Veenendaal, Ian, Sudiwala, Rashmikant ORCID: https://orcid.org/0000-0003-3240-5304, Tucker, Carole ORCID: https://orcid.org/0000-0002-1851-3918, Walker, Ian K., Braithwaite, Lottie, Winter, Berend, Savini, Giorgio, Shitvov, Alexey, Zhang, Jin, Gudmundsson, Jon E., Pisano, Giampaolo ORCID: https://orcid.org/0000-0003-4302-5681, Coyle, Laura E., Perrin, Marshall D. and Matsuura, Shuji 2024. Development and precision characterisation of broadband anti-reflection-coated mm-wave components. Presented at: Space Telescopes and Instrumentation: Optical Infrared and Millimeter Wave, Yokohama, Japan, 16–21 June 2024. Published in: Coyle, Laura E., Matsuura, Shuji and Perrin, Marshall D. eds. Proceedings, Space Telescopes and instrumentation: Optical Infrared and Millimeter Wave. , vol.13092 SPIE, pp. 211-1309276. 10.1117/12.3018886

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Abstract

Future optical systems in the sub-mm range require low loss, low reflectance and broadband optics. Presented here is the development process for a hot press technique for making broadband multi-layer anti-reflection coatings for plastic lenses and optical components. The elevated temperatures used in this method induce a change in index and mechanical deformation in the substrate material due to polymer chain rearrangements. To avoid this, these components are annealed before they are machined to their intended form and prior to the application of any coating. Study of precise dimensional and refractive index changes between 115-130°C across repeated annealing cycles shows that ultra-high molecular weight polyethylene (UHMWPE) requires 3-4 annealing cycles above 125°C before stabilisation. We then present 3 and 5 layer test coating recipes for 90-225GHz with comparison between experimental measurements and theory. Preliminary results show good agreement. In this study, the methods presented are kept generic for any sub-mm band focusing broadly on 60-600GHz; however future work will apply what is achieved for future CMB experiments.

Item Type:	Conference or Workshop Item (Paper)
Date Type:	Publication
Status:	Published
Schools:	Physics and Astronomy
Publisher:	SPIE
ISSN:	0277-786
Date of First Compliant Deposit:	14 November 2024
Date of Acceptance:	23 August 2024
Last Modified:	27 Nov 2024 10:42
URI:	https://orca.cardiff.ac.uk/id/eprint/174000

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