Optical Camouflage is a piece of equipment, featured in the Call of Duty: Black Ops II campaign. First found in "Celerium", the player is able to get it once they go indoors into the underground lab using the Access Kit. By pressing (on PC), or on the D-Pad, the player can cloak themselves with the surroundings, but the weapon equipped by the player will not be affected by the camouflage, due to it being an outside agency.
The player can also obtain it in the mission "Achilles' Veil", by going downstairs at the right tower and hacking a box. Despite what it may seem at first, it does not seem to hide the player from enemies, rather it significantly decreases their accuracy, possibly due to an oversight. Mercs have it equipped during the levels "Celerium" and "Judgement Day". The camo modifies the player's vision to some degree, giving the screen a minor green tint. The camo also emits a high-pitched shriek when active.
Optical Camouflage also makes a minor appearance as a collectible item in Call of Duty: Black Ops III, where a damaged one can be found in Singapore. It was apparently used by the 54 Immortals and was state-of-the-art technology manufactured by the Common Defense Pact, who supplied it to the Immortals.
According to the Data Vault in Black Ops III, Optical Camouflage is intended to be worn as an outer layer over regular body armour. It is made of a smart metamaterial which causes light falling on it to 'flow' around the surface, emerging on the opposite side but still travelling in the same direction, rather than bouncing back off the material, preventing the wearer from being seen. The wearer could control the surface electronically, making themselves selectively invisible in either the visible spectrum or infrared spectrum, rendering them invisible to infrared based targeting systems. If the control circuity for the power regulators was damaged, the metamaterials would alter their properties at random, causing parts of the cloak to fade in and out. This would render it useless as camouflage, though the visual effect was noted to be quite hypnotic.