Spock used a trident scanner while he attempted to repair the Galileo, after the shuttlecraft had been brought down on the Companion's homeworld. The scanner, however, was short-circuited and destroyed by the Companion when Spock attempted to make physical contact with it. (TOS: "Metamorphosis")
In 2267, Ensign Harper used a trident scanner to connect the M-5 computer to the USS Enterprise's main power plant. He later attempted to disconnect M-5 with a trident scanner, but was vaporized by the advanced computer for his troubles. (TOS: "The Ultimate Computer")
The same year, Lieutenant Commander Montgomery Scott, leading a repair party aboard the USS Constellation, employed a trident scanner to cross-connect the warp drive control circuits to those of the impulse engines. (TOS: "The Doomsday Machine")
The term used here, "trident scanner," comes solely from the script for "Trials and Tribble-ations," where the device is apparently named after its general shape, which resembles a trident.