Ultraviolet photography sensor will pick up reflected infrared radiation as well as ultraviolet, which may obscure the details that would be resolved by ultraviolet alone. Most types of glass will allow longwave UV to pass, but absorb all the other UV wavelengths, usually from about 350 nm and below. For UV photography it is necessary to use specially developed lenses having elements made from fused quartz or quartz and fluorite. Lenses based purely on quartz show a distinct focus shift between visible and UV light, whereas the fluorite/quartz lenses can be fully corrected between visible and ultraviolet light without focus shift. Examples
UV marker emits visible light and make the message readable for human eyes. Fluoresce is caused by a conversion of energy; when the invisible ultraviolet falls on the fluorescent surface, it is absorbed and re-emitted as visible light radiation. The absorption of energy by the electrons in the UV-visible ink enables this to happen. When an extra amount of energy is absorbed, the electrons jump into higher energy orbital patterns surrounding the nucleus. Eventually, the energy is released as visible light when they fall back to their normal orbital shell. The difference between the original electron orbital and the new orbital pattern