Electromagnetic scanner
From Memory Alpha, the free Star Trek reference.
An electromagnetic scanner is a device used to scan the EM spectrum.
The USS Enterprise-D was equipped with an electromagnetic scanner.
When the ship was infested by nanites in 2366, Captain Jean-Luc Picard ordered Worf to prepare to activate the gamma pulse generator in order to kill the nanites, if necessary. To scan for the tiny robots, Worf used the electromagnetic scanner. (TNG: "Evolution")
