A light designed to emit ultraviolet light (at a wavelength of approximately 365 nm) to illuminate parts of the body to observe fluorescence for diagnostic purposes. It is typically used to help diagnose dermal fungal infections (e.g., Microsporum audouini), bacterial infections (e.g., Corynebacterium minutissimum, Pseudomonas), parasitic infections (e.g., scabies), and pigmentary disorders (e.g., vitiligo). It also often used to examine rape victims for sperm residues or examine a patient's eyes for corneal lesions.