The LED flash is a white LED. The luminous principle of white light is blue light+phosphor, or multi-color light mixed into white light. Ultraviolet rays are more expensive, consume more energy and have low brightness. Moreover, most of the light emitted by the ultraviolet diode is purple light, and a small part is ultraviolet light. In quantum physics, it is clearly pointed out that the higher the frequency of electromagnetic waves, the greater the energy. This consumes a lot of mobile phone batteries, and the brightness is not high, so there is no need to use it.