Belongs to the electromagnetic waves at the lower boundary of visible light (200 - 400 nm). A source of light that is frequently used in document examination to analyse paper brightness, fluorescent inks and other security features as well as tampering. The main UV sources used in document examination are UV sources with 365/366 nm (long-wave UV), 313 nm (medium wave UV) and 254 nm (short-wave UV) wavelength radiation. Ultraviolet "light" is not visible itself, only its effect, i.e. the visible fluorescence stimulated by UV light can be seen ( fluorescent ink, etc.).
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