The theta-matrix compositor was a device aboard Federation starships in the 24th century, such as the Galaxy-class and the Intrepid-class.

It was used to recrystallize dilithium crystals while still in the articulation frame of a warp core. This compositor made the recrystallization process ten times more efficient than on Excelsior-class-ships. (TNG: "Family"; VOY: "Innocence")