'Invisibility Cloak' Created Using Crystals 98
Zothecula writes "The quest to build a working 'invisibility cloak' generally focuses on the use of metamaterials – artificially engineered materials with a negative refractive index that have already been used to render microscopic objects invisible in specific wavelengths of light. Now, using naturally occurring crystals rather than metamaterials, two research teams working independently have demonstrated technology that can cloak larger objects in the broad range of wavelengths visible to the human eye. PDFs of the two similarly named research papers are available through arXiv.org."
Re:I dunno (Score:3, Informative)
From reading the article I get mostly that it's done all with Mirrors and prisms essentially.
It is actually slightly more sophisticated than that. They use the birefraction properties of calcite to bend the light rays in such a way that the exiting light has the exact same position and direction as if there were no wedge at the bottom. A simple mirror/prism assembly can not do this. It will either shift the beam or tilt it slightly.
The reason you see the wedge in the picture is because of lousy polishing. The tip of the wedge is not perfectly sharp.