The Serosian term for a hologram, used of Dejaren, the unstable maintenance projection who murdered his ship's organic crew in the Voyager episode Revulsion.
Isomorphic projections are holograms built by the Serosians to do dirty and dangerous work aboard their ships. The only one seen is Dejaren, an HD25 model who sends a distress call in the episode Revulsion claiming that his crew has died of a virus.
The Doctor, delighted to meet another hologram and newly free to travel thanks to his mobile emitter, goes across with B'Elanna Torres. Dejaren is fascinated by the Doctor's standing among his crew, but his disgust for organic life, with its eating and decay, becomes harder to hide.
Torres finds the bodies of the crew he killed after years of contempt and confinement. Dejaren attacks her, reaching into her chest, and she manages to destroy his projection matrix before he can kill them both.