Refraction of Light Rays by Material with Negative Refractive Index
This Demonstration shows the effect of negative refraction. Light rays are emitted by a point source . The light rays impinge on a plate of material with negative refractive index . At the two surfaces of the plate, the light rays are refracted according to Snell's law.
The refractive index of the plate is negative (). Materials with negative refractive index do not exist in nature, but there are attempts to produce composite materials with this property.
With the help of the Demonstration, it can be seen that for , a flat plate can focus light rays, and that if , the image of the point source is a point.
The Demonstration is also available as a web app on the Firefox Marketplace from https://marketplace.firefox.com/app/negative-refraction-of-ligh/
 V. Veselago, "The Electrodynamics of Substances with Simultaneously Negative Values of and ," Soviet Physics Uspekhi, 10(4), 1968 pp. 509–514.
 J. B. Pendry, "Negative Refraction Makes a Perfect Lens," Physical Review Leters, 85(18), 2000 pp. 3966–3969. doi:10.1103/PhysRevLett.85.3966.
 G. V. Eleftheriades and K. G. Balmain, Negative-Refraction Metamaterials, Hoboken, NJ: John Wiley & Sons, 2005.