Another name for “ultraviolet” or “black” light, produced using a discharge lamp inside an envelope of intensely pigmented glass, is “Wood’s Light.” American physicist Robert Williams Wood pioneered his Wood’s Glass filter in 1903, which lets ultraviolet and infrared light pass through while blocking most visible light. Used for covert communications during World War I, it has since been mostly replaced by less costly technologies that are also less prone to breakage. But “Wood’s Light” references to various UV lights remain.
-Nook Schoenfeld
