The Anachronism Detector, also called the Decontaminator, is a device used by the DIC and Despatch to scan transdimensionally-snatched characters for foreign materials so that their canon isn't violated upon their return. It should always be used on canon characters and agents when moving between continua.
The Anachronism Detector is comprised of a wand and a control box, similar to the portable metal detectors used in airports. The wand is waved over the target character, and if anything anachronistic is detected, the device beeps.
Unfortunately, it's not that simple to use. The control box must be set for the world, then the character under analysis, then an exact reference for the time that the character is going back to according to the copy of the book or other media you're using. It has to be calibrated each and every time you use it; there are no default settings.