A metamaterial telescope at millimetre wavelengths

TL;DR

This paper introduces a novel broadband millimeter-wave telescope made entirely of flat metamaterial lenses, demonstrating comparable performance to traditional telescopes with significant weight and complexity reductions.

Contribution

The paper presents the design, fabrication, and testing of a metamaterial-based flat lens telescope operating between 90 and 190 GHz, a first of its kind in this frequency range.

Findings

Achieved >80% weight reduction compared to conventional telescopes.

Demonstrated good agreement between measurements and models.

Showed the telescope's performance is comparable to traditional designs.

Abstract

In this paper we present a novel telescope composed exclusively of thin, flat optical elements, each being a hot-pressed multi-layered structure combining the properties of a lens, its anti-reflection coating and frequency selection or filtering. We discuss the design process, from fundamental physical metamaterial properties of the single periodic cell structure to the lens concept, which constitutes the building block of the telescope design, and the iterative process that is part of the lens optimization. We provide the results of a laboratory test campaign for different telescope designs based on three-lens arrangements. Beam cuts and focus measurements both on- and off-axis are compared with models showing good agreement. We conclude that a broad-band mm-wave complete telescope system consisting entirely of metamaterial flat lenses has been built and tested, showing comparable performance with conventional state-of-the-art refractive telescopes in the same wavelength region. This new broadband design, highly efficient at frequencies between 90 and 190 GHz, offers multiple advantages. These include a $> 80\%$ weight reduction, reduced issues tied to coating-survivability at cryogenic temperatures caused by differential contraction exacerbated by non-flat surfaces, as well as a reduction in the overall number of components and mechanical mounts.