![Uhura Chekov collector](https://cdn.statically.io/img/static.wikia.nocookie.net/memoryalpha/images/4/45/Uhura_Chekov_collector.jpg/revision/latest/scale-to-width-down/180?cb=20120317045132&path-prefix=en)
A collector collecting photons
A collector was an engineering tool that could gather and store energy.
In 1986, it was used by Nyota Uhura and Pavel Chekov for collecting high energy photons from a nuclear fission reactor on board the USS Enterprise. Later, the photons from this device were streamed back into the dilithium chamber of the HMS Bounty. This was done to re-crystallize the dilithium crystals. (Star Trek IV: The Voyage Home)
Another name for the collector was the collecting device. [1]