Phaser range
From Memory Alpha, the free Star Trek reference.
The phaser range is a facility aboard some starships, that allow Starfleet personnel to practice aiming and firing their phasers. It consists of a circular stage set in a large empty area. The area around the stage is illuminated, but everywhere else is dark. Flashing spheres of light of different colors and moving at various speeds serve as the targets. Two people can be accommodated on the stage at any one time. (TNG: "A Matter Of Honor", "Redemption")
When first arriving aboard station Deep Space 9, Julian Bashir asked Odo if the station had an area where he could practice with his phaser. (DS9: "Emissary")
