Drew Wilson
February 4th, 2011, 03:23 PM
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.
Both teams, one from the Singapore-MIT Alliance for Research and Technology (SMART Centre) and the other comprised of researchers from the University of Birmingham, Imperial College, London and Technical University of Denmark, made the breakthrough using a natural crystal called calcite.
This transparent mineral boasts an optical property known as birefringence, or double-refraction. This means that when light enters the calcite, it splits into two rays of different polarizations traveling at different speeds and in different directions. This causes objects viewed through a clear piece of calcite to appear doubled.
To create their invisibility cloak, the University of Birmingham team glued two pieces of calcite with differing optical paths together and placed them on a mirror and performed demonstrations in both air and a container of liquid.
More... (http://www.gizmag.com/invisibility-cloak-hides-larger-object-without-use-of-metamaterials/17782/)
I would imagine the military would be VERY interested in something like this.
Both teams, one from the Singapore-MIT Alliance for Research and Technology (SMART Centre) and the other comprised of researchers from the University of Birmingham, Imperial College, London and Technical University of Denmark, made the breakthrough using a natural crystal called calcite.
This transparent mineral boasts an optical property known as birefringence, or double-refraction. This means that when light enters the calcite, it splits into two rays of different polarizations traveling at different speeds and in different directions. This causes objects viewed through a clear piece of calcite to appear doubled.
To create their invisibility cloak, the University of Birmingham team glued two pieces of calcite with differing optical paths together and placed them on a mirror and performed demonstrations in both air and a container of liquid.
More... (http://www.gizmag.com/invisibility-cloak-hides-larger-object-without-use-of-metamaterials/17782/)
I would imagine the military would be VERY interested in something like this.