Targeting holo-emitter
A targeting holo-emitter was a small, circular device used by Earth Starfleet and Military Assault Command Operations (MACO) personnel as a holographic projector for target practice during the 22nd century.

In 2151, Lieutenant Malcolm Reed set up a targeting holo-emitter in the armory of the  starship . This enabled Ensign Hoshi Sato to practice firing a phase-pistol, as she was unfamiliar with doing so at that time. ()

In 2152, Reed and Sato used a targeting holo-emitter in Enterprises armory to teach Maklii and two other members of a deuterium mining colony how to use rifles designed by their own species. ()

The MACOs used holo-emitters in a "specialized training system" (as worded by General J. Hayes) which they developed at Jupiter Station in 2153. In this target practice method, the holo-emitters were operated from a control console and could simulate a variety of targets, including normal-sized ones as well as smaller ones that the regular-size targets could divide into. MACO holo-emitters were operated in the gymnasium aboard Enterprise a few months after they were developed, as part of training there that involved not only MACOs but also members of the ship's senior staff. ()

Holographic technology