Phaser sweep

From Memory Alpha, the free Star Trek reference.

A phaser sweep is a procedure in which a phaser emitter, typically mounted on the wall of a room, emits a phaser burst that covers the entire area of the room, usually on a setting of three or four.

When this procedure takes place, any Changeling present in the room will convert back to its gelatinous state, making the Changeling detectable.

In early 2372, the crew of Deep Space 9 used phaser sweeps to find Odo, who was helping them to train for a possible infiltration of the station by the Founders. (DS9: "The Way of the Warrior")

This procedure was used again later that year when a Dominion infiltration of Changelings was thought to have occurred on Earth. These phaser sweep devices were implemented in all Starfleet and Federation installations on Earth under orders from Captain Sisko, who was temporarily promoted to head of Starfleet security. (DS9: "Homefront", "Paradise Lost")

Phaser technology
Tools: phaser bore • phaser drill
Weapons: Bajoran phaser • compression phaser rifle • Galor-class phaser bank • hand phaser • Kzinti phaser • particle phaser • phaser array • phaser bank • phaser cannon • phaser emitter • phaser type-1 • phaser type-2 • phaser type-3 • phaser type-4 • phaser type-8 • Regalian phaser rifle • regenerative phaser
Other: phaser coil • phaser range • phaser relay • phaser room • phaser sweep