Torches with ultraviolet mode (UV)

Ultraviolet (UV)

— illumination in the ultraviolet range is mainly used to identify objects and traces that are invisible under normal lighting. One of the most popular ways to use this feature is with a makeshift currency detector: most modern bills have markings that glow under UV light. Also, such light can be used to detect inscriptions with "invisible" ink (including marks on the same bills), some biological (for example, blood) and chemical liquids (in particular, UV-sensitive compounds can detect leaks in pipes and liquid contours), etc. Note that the UV emitter usually glows in the visible range — with a characteristic bluish tint; this allows you to accurately determine whether such a light is on or off.