Ultraviolet or UV torches are incredibly handy tools for many specialised scenarios and applications. The fact that UV torches emit ultraviolet light gives them a range of unique uses and abilities that are beyond the range - quite literally, in terms of the visible light spectrum - of standard torches and handlamps.

What are UV torches used for, and how do they work?

• UV torches and handlamps emit light at a different wavelength to standard non-UV flashlights - ultraviolet radiation is a type of light energy that sits outside the scope of the human eye on the light spectrum
• Ultraviolet light - sometimes referred to as ‘black light' - causes certain compounds and chemicals to fluoresce vividly when it hits them, rendering them brightly visible when they typically wouldn't be under non-UV lighting
• This fluorescence occurs because various types of inks, chemicals and biological agents tend to absorb certain ‘colours' of light - in this case, ultraviolet - which causes them to emit another colour of light which does fall in the visible spectrum for humans
• Working under UV light therefore enables immediate visual identification of various chemicals and substances that would typically go unnoticed in daylight or standard electric torches running on regular LED or incandescent bulbs
• Among the most common workplace environments where UV torches are needed on a regular basis are in law enforcement and the emergency services, as well as in laboratory, medical and pharmaceutical settings, and increasingly in commercial settings as a means of forgery detection (UV torches are frequently used for checking markings on banknotes)

Note that ultraviolet light itself occupies a fairly broad chunk of bandwidth on the overall light spectrum, and that there are several different ‘kinds' of UV. Some are harmful to human skin when exposed for longer periods.

While this isn't generally the case for ‘near-ultraviolet' light, which is most standard LED UV torches emit, the latter can be harmful to human vision if shone directly at the eyes. UV torches should always be used with caution in accordance with manufacturer guidelines, and under supervision for less inexperienced users.