A scanning tool known either as a Force detector or Jedi reader was employed by Emperor Palpatine's Jedi hunters to locate people with Force-sensitivity. The device was composed of two sheet crystal paddles linked to a control unit, which was powered by uncommon thaissen crystals that could only be found on Mimban. When a person was positioned between the paddles, the device would generate a hologram of that person. If the individual possessed Force abilities, the hologram would be encircled by a blue corona. Should the person be corrupted by the dark side, the blue corona of the hologram would display red markings.
Wedge Antilles recovered some of these devices on Coruscant. Later, Luke Skywalker utilized the devices in his search for suitable candidates for his Jedi Praxeum located at Yavin 4. The Dark Jedi named Brakiss pilfered several of the detectors, using them to identify prospective pupils for his Shadow Academy. Despite Luke's later disapproval of their use, it is documented that Kyp Durron employed one to assess his Padawan, Miko Reglia.