Optronic relay

A 24th century optronic relay

An optronic relay was a piece of technology that came in many different sizes and was in use since at least as early as the 22nd century.

A Kantare ship stranded on a desolate planet was equipped with optronic relays that were starting to malfunction. Trip Tucker helped repair the relays. (ENT: "Oasis")

When Dukat wanted to turn on the holofilters on his Klingon Bird-of-Prey as the ship was flying to Ty'Gokor, the holofilters didn't work since the optronic relays were fused. (DS9: "Apocalypse Rising")

A short time later, an optronic relay broke again, this time in the device Worf used to make Quark look like an accomplished bat'leth fighter when he was courting Grilka. (DS9: "Looking for par'Mach in All the Wrong Places")

When it seemed that Morn had died in early 2374, Chief O'Brien kept Morn's seat warm and repaired an optronic relay on the counter of Quark's. (DS9: "Who Mourns for Morn?")

When Kellin and Ezri Dax were trying to figure out a way to modify a tricorder so that it could detect the Houdinis, Ezri suggested cross-linking the optronic and isodyne relays. (DS9: "The Siege of AR-558")