Wood's lamp

A Wood's lamp is a diagnostic tool used in dermatology by which ultraviolet light is shone (at a wavelength of approximately 365 nanometers) onto the skin of the patient; a technician then observes any subsequent fluorescence. For example, porphyrins — associated with some skin diseases — will fluoresce pink. Though the technique for producing a source of ultaviolet light was devised by Robert Williams Wood in 1903 using "Wood's glass", it wasn't until 1925 that the technique was used in dermatology by Margarot and Deveze for the detection of fungal infection of hair.

Clinical use
Wood's light is useful in diagnosing conditions such as tuberous sclerosis and erythrasma, both in distinguishing them from other conditions and in locating the precise boundaries of the condition. It is also helpful in diagnosing fungal infections (Microsporum audouini), bacterial infections (Corynebacteriium minutissimum, Pseudomonas), and pigmentary disorders.

Furthermore, a Wood's lamp may be used to rapidly assess whether a subject is suffering from ethylene glycol poisoning as a consequence of antifreeze ingestion. Manufactures of ethylene glycol containing Antifreezes commonly add fluorescein, which causes the patient's urine to fluoresce under Wood's Lamp.

Its use in detecting melanoma has been reported.