▁devices ▁to ▁jam ▁and ▁conf use ▁remote ▁sens ing ▁devices ▁would ▁greatly ▁aid ▁in ▁this ▁process , ▁but ▁is ▁more ▁properly ▁referred ▁to ▁as ▁" active ▁cam ou fl age ". ▁Alternatively , ▁met am aterial s ▁provide ▁the ▁theoretical ▁possibility ▁of ▁making ▁elect romagnet ic ▁radiation ▁pass ▁freely ▁around ▁the ▁' clo aked ' ▁object . ▁ ▁Met am aterial ▁research ▁ ▁Opt ical ▁met am aterial s ▁have ▁featured ▁in ▁several ▁recent ▁propos als ▁for ▁in visibility ▁schemes . ▁" Met am aterial s " ▁refers ▁to ▁materials ▁that ▁o we ▁their ▁ref ract ive ▁properties ▁to ▁the ▁way ▁they ▁are ▁struct ured , ▁rather ▁than ▁the ▁subst ances ▁that ▁compose ▁them . ▁Using ▁transformation ▁opt ics ▁it ▁is ▁possible ▁to ▁design ▁the ▁optical ▁parameters ▁of ▁a ▁" clo ak " ▁so ▁that ▁it ▁gu ides ▁light ▁around ▁some ▁region , ▁rendering ▁it ▁invisible ▁over ▁a ▁certain ▁band ▁of ▁w avel ength s . ▁ ▁These ▁spatial ly ▁varying ▁optical ▁parameters ▁do ▁not ▁correspond ▁to ▁any ▁natural ▁material , ▁but ▁may ▁be ▁implemented ▁using ▁met am aterial s . ▁There ▁are ▁several ▁theories ▁of ▁clo aking , ▁giving ▁rise ▁to ▁different ▁types ▁of ▁in visibility . ▁In ▁ 2 0 1 4 , ▁scient ists ▁demonstrated ▁good ▁clo aking ▁performance ▁in ▁mur ky ▁water , ▁demonstr ating ▁that ▁an ▁object ▁shr oud ed ▁in ▁fog ▁can ▁disappear ▁completely ▁when ▁appropri ately ▁co ated ▁with ▁met am aterial . ▁ ▁This ▁is ▁due ▁to ▁the ▁random ▁scatter ing ▁of ▁light , ▁such