Ultraviolet light is outside of violet light, and the wavelength range is between 400-180nm. The method of using ultraviolet light to irradiate the human body to treat diseases is called ultraviolet therapy. According to the biological effect is divided into: short-wave ultraviolet (UVC), wavelength range 280-180nm; medium-wave ultraviolet (UVB), wavelength range 320-280nm; long-wave ultraviolet (UVA), wavelength range 400-320nm. The role of ultraviolet 1, anti-inflammatory and bactericidal effect: UV can inactivate 90% of bacteria, but the energy required for various bacteria is different Shanghai Oriental 2, analgesic effect: the amount of erythema irradiation promotes the tissue to exclude pain-causing substances, the pain threshold rises, and the excitability of skin sensory nerves decreases. 3, desensitizing effect: stimulate the production of histamine enzyme to break down the excess histamine in the body during allergic reactions, playing a desensitizing role. 4.Promote tissue repair: used in the treatment of open wounds, stubborn skin or mucous membrane ulcers. 5, immune effect: UV irradiation can increase immunoglobulin formation, complement activity, reticuloendothelial system and leukocyte phagocytosis, thus improving the immune function of the body. Main indications: 1, psoriasis vulgaris 2, vitiligo 3, mycosis fungoides (MF) early 4, eczema, atopic dermatitis 5, pityriasis rosea 6, chronic mossy pityriasis, acute acneiform pityriasis 7, baldness 8, herpes zoster 9, chronic ulcers 10, folliculitis, boils, carbuncles, dermatitis 11, palmoplantar pustulosis 12, hand contact dermatitis 13, frostbite Contraindications: 1, pigmented dry skin disease 2, other photosensitive diseases (such as albinism, etc.) 3, lupus erythematosus 4, pregnancy, lactation, infants and children 5, patients with uremia and liver failure 6, patients with cataracts and aphakia 7, immunosuppressive patients 8, patients with a family history of melanoma 9, patients with a history of ionizing radiation or arsenic treatment