Visibly invisible

Specially fabricated calcite crystals are all that is needed to make a so-called "invisibility cloak", a material that renders an otherwise opaque object transparent to visible light. Teams in the UK and in the US and Singapore both recently published details of how calcite can manipulate the path of coherent laser light so that objects beneath the crystals are hidden from view. The US team's approach works under water and can hide an object and big and solid as a paperclip with single-color laser light. The UK researchers avoid the need to submerge their system in water and have also achieved cloaking with incoherent white light rather than lasers. Both approaches side step the composite meta materials used in earlier work that made objects invisible only in wavelengths beyond the visible spectrum.