Once standard fantasy in the world of science fiction, invisibility cloaks are viable products as of 2014. There are three types of invisibility cloaks. The first uses carbon nanotube, another uses metamaterials, and the third uses optical camouflage technology.
Invisibility cloaks that use carbon nanotubes essentially create a mirage effect to trick the viewer into thinking he is seeing something else. To make this happen, sheets of carbon nanotube are rolled in a cylindrical fashion and electrically heated. The heat is then transferred to the surrounding area of water which causes the light to bend, adequately making anything behind it appear invisible.
Invisibility cloaks using metamaterials use concentric gold rings that are injected with polarized cyan light to effectively divert incoming light waves away from the object to make it appear invisible. As of 2014, this technology is expected to be used to hide stationary objects, such as buildings and tanks, rather than to hide humans.
As of 2014, the final type of invisibility cloak made with optical camouflage technology is the only one that is actually wearable as a garment. It creates an optical illusion using a highly reflective garment and a variety of computers, cameras, projectors and mirrors. All of these objects work together to send computer-generated information to a person's sensory perceptions with the aid of a viewing apparatus. The result is that the viewer's brain is "tricked" into not seeing the hidden object.