The Lens was an object that allowed for the transfer of energy through dimensions. Norton Folgate boarded Flight 405 on a mission from the Committee to obtain it, but the flight was caught in the Rift and was stuck in a time loop for sixty years.
Norton used to Lens to hijack Yvonne Hartman's attempted summoning of Ianto Jones. His projection helped free his real self and he and Yvonne took the Lens to the Committee. (AUDIO: Flight 405) Norton used the Lens to divert the energy from the Sorvix power station to the Rift to save the world after realising that the Committee planned to wipe out the planet. (AUDIO: Eye of the Storm)