Light Collimation and Focussing by a Thin Flat Metallic Slab

TL;DR

This paper demonstrates that a thin flat metallic slab can effectively collimate and focus light from a point source, with optimal performance near the plasma frequency and low imaginary permittivity, supported by experiments and theoretical analysis.

Contribution

It introduces a novel method of light collimation and focusing using flat metallic slabs, supported by experimental validation and theoretical modeling.

Findings

Silver slabs in visible light achieve effective collimation.

Low imaginary permittivity enhances collimation quality.

Aluminium's small imaginary permittivity at UV plasma frequency is promising.

Abstract

We present experimental and theoretical work showing that a flat metallic slab can collimate and focus light impinging on the slab from a punctual source. The effect is optimised when the radiation is around the bulk, not at the surface, plasma frequency. And the smaller the imaginary part of the permittivity is, the better the collimation. Experiments for Ag in the visible as well as calculations are presented. We also discuss the interesting case of the Aluminium whose imaginary part of the permittivity is very small at the plasma frequency in UV radiation. Generalization to other materials and radiations are also discussed.