Editing Parabolic reflector (section)

== History ==

The principle of parabolic reflectors has been known since [[classical antiquity]], when the mathematician [[Diocles (mathematician)|Diocles]] described them in his book ''On Burning Mirrors'' and proved that they focus a parallel beam to a point.<ref name="AutoVC-3"/> [[Archimedes]] in the  third century BCE studied paraboloids as part of his study of [[hydrostatic equilibrium]],<ref name="AutoVC-4"/> and it has been [[Archimedes#Discoveries and inventions|claimed]] that he used reflectors to set the Roman fleet alight during the [[Siege of Syracuse (212 BCE)|Siege of Syracuse]].<ref name="AutoVC-5"/>  This seems unlikely to be true, however, as the claim does not appear in sources before the 2nd century CE, and Diocles does not mention it in his book.<ref name="AutoVC-6"/>  Parabolic mirrors and reflectors were also studied extensively by the [[physicist]] [[Roger Bacon]] in the 13th century AD.<ref name="AutoVC-7"/> [[James Gregory (astronomer and mathematician)|James Gregory]], in his 1663 book ''Optica Promota'' (1663), pointed out that a [[reflecting telescope]] with a mirror that was parabolic would correct [[spherical aberration]] as well as the [[chromatic aberration]] seen in [[refracting telescope]]s. The design he came up with bears his name: the "[[Gregorian telescope]]"; but according to his own confession, Gregory had no practical skill and he could find no optician capable of actually constructing one.<ref name="AutoVC-8"/> [[Isaac Newton]] knew about the properties of parabolic mirrors but chose a spherical shape for his [[Newtonian telescope]] mirror to simplify construction.<ref name="AutoVC-9"/> [[Lighthouse]]s also commonly used parabolic mirrors to collimate a point of light from a lantern into a beam, before being replaced by more efficient [[Fresnel lens]]es in the 19th century. In 1888, [[Heinrich Hertz]], a German physicist, constructed the world's first parabolic reflector antenna.<ref>{{cite web | url=http://www.nrao.edu/whatisra/hist_prehist.shtml | title=Prehistory of Radio Astronomy|website=www.nrao.edu}}</ref>