The light chamber was a device designed by Prince Albert and George MacLeish to combat the threat of Werewolves in the Scottish highlands. MacLeish built it by hand, spending much of his fortune to do so.
Albert and MacLeish positioned it in Torchwood House, MacLeish's residence, where focused the light of the Moon to such a degree that the Koh-i-Noor would amplify its power.
Most took it to simply be a telescope as it had the appearance of one. However, if one attempted to use it in this manner, the image was out of focus.
In 1879, after both Albert and MacLeish's deaths, the light chamber was used by the Tenth Doctor and Rose Tyler to kill a "Werewolf" that was attempting to infect the Queen. (TV: Tooth and Claw)