In science fiction stories or superhero comics, X-ray vision is the supernatural ability to see through normally opaque physical objects at the discretion of the holder of this superpower.
As depicted, x-ray vision is actually more of a form of the supposed psychic ability of remote viewing.
Such devices are being deployed in some airports as a way of detecting contraband, such as guns, knives, and any other weapons in particular which may be carried beneath a person's clothing, bag, etc.
The devices have created some degree of controversy from personal privacy advocates who worry about screeners being able to see people "naked."
In comic books in the latter half of the 20th century, there often appeared an advertisement for "X-ray specs" which displayed the face of a smiling boy wearing glasses with spirals on the lenses looking at his hand through which he could see the bones.