text: One of the innovations for night and all-weather flying used by the US, UK, Japan and Germany during World War II was the use of UV interior lighting to illuminate the instrument panel, giving a safer alternative to the radium-painted instrument faces and pointers, and an intensity that could be varied easily and without visible illumination that would give away an aircraft's position. This went so far as to include the printing of charts that were marked in UV-fluorescent inks, and the provision of UV-visible pencils and slide rules such as the E6B.
  They may also be used to test for LSD, which fluoresces under black light while common substitutes such as 25I-NBOMe do not.
  Strong sources of long-wave ultraviolet light are used in tanning beds.