The visible light range of human eyes is 380nm - 880nm, while the wavelength of UVC is below 280nm, which belongs to invisible light. Therefore, human eyes cannot recognize the strength and color difference of pure UVC light. We can see the color difference of UVC lamp beads through human eyes. In fact, human eyes see light with wavelengths between 380-880nm, that is, the color difference seen by human eyes is light in non UVC band, and this part of light does not have sterilization function.

As for the causes of color difference, there are two factors: 1. During the epitaxial growth of AlGaN material, O element leads to the change of epitaxial layer surface, resulting in energy migration and impurity peak. 2. The light emitted by the chip is irradiated on the scaffold. The fluorescent material on the scaffold is excited by 280nm deep ultraviolet light and emits light of other colors. Because different epitaxial wafers are affected by O element, the heteropeaks are different. At the same time, the fluorescent substances on the scaffold are excited by UV, and the color of the light may be different. So there will be different colors of stray light. That is, there are color differences visible to the naked eye