Wood&;s lamp is made up of -

WOOD'S LAMP Hand held device used to diagnose various dermatological conditions. It is a mercury vapour long wave,ultraviolet lamp with an inbuilt wood's filter made of barium silicate with 9% nickel oxide. Opaque to all wavelengths except those between 320 nm and 400 nm with a peak at 365 nm.Flourescence occurs when wood's light is absorbed and radiation of longer wavelengths is emitted.Examination done in dark room. Tinea capitis-greenish fluorescence extent of pigmentation. Epidermal/dermal bacterial infection- pseudomonas infection yellowish-greeen fluorescence diagnosis of prophyria- reddish fluorescence in urine iadvl textbook of dermatology page 109