UV light is an invisible light, because it exists outside the ultraviolet light in the spectrum, so it is called UV rays. According to the spectrum, long ultraviolet light wavelength is between 320nm to 400nm. The centre number is 365nm and 395nm. UV flashlight with this wavelength is used in many fields such as fluid system leak checking, oil spots detection, industry glue solidification, fluorescent detection, criminal investigation, medical treatment, etc.<\/p>\n