Fluorescence reaction refers to a process in which a substance is excited after being irradiated with ultraviolet and invisible light, and then converts the excited energy into visible light to release. This is a cold glow phenomenon of photoluminescence. Fluorescence reaction is very common in nature, a variety of animal bodies (such as shrimp, crab, jellyfish, etc.), food (such as soy sauce, Pu'er tea, liquor, coffee, etc.), drugs, plant extracts (such as ginkgo brass, peony, bitter Ginseng alkaloids, etc.), chlorophyll, microorganisms (bacteria, mold) can produce a fluorescent reaction under ultraviolet light irradiation, which is natural fluorescence, is the inherent characteristics of the substance and is harmless.