Ultraviolet (UV) radiation is a part of the electromagnetic spectrum that extends from the end of visible light through to X-rays. This part of the spectrum is undetectable to the naked eye, with only a few insects capable of seeing it, but it’s indirectly visible to us via fluorescent objects, which emit the radiation at a lower energy level.
The spectrum of ultraviolet light lies between the wavelengths of 400 nanometres (near-visible light) through to just ten nanometres (near-X-ray). This spectrum is divided into four major categories: near (400-300 nanometres), middle (300-200 nanometres), far (200-100 nanometres) and extreme (100-10 nanometres). It’s also split into ten subtypes, which possess different qualities for various applications.