黑光灯又称紫外线灯或伍德灯（Wood's lamp），是发射长波紫外线(UV-A)和少量可见光的灯，又叫做UV-A 灯， 黑光灯有深紫色的过滤材料，在电灯泡上或者在分开的玻璃过滤器中，用来过滤可见光，同时允许紫外线通过， 因此在工作时有紫光。 这种有过滤材料的黑光灯在工业中以字母“BLB”(black light bulb)标明。

另外一种没有过滤材料的电灯泡在工作时产生更多可见光并呈现蓝色，这种灯一般用于捕蚊灯，工业上标记为“BL”

黑光灯光源可以来自特殊设计的荧光灯、汞蒸汽灯、发光二极管或者白炽灯。在医学，司法科学及其他科学领域这种光源被称作伍德灯（以Robert Williams Wood 命名）。

A blacklight (or often black light), also referred to as a UV-A light, Wood's lamp, or simply ultraviolet light, is a lamp that emits long-wave (UV-A) ultraviolet light and not much visible light.

One type of lamp has a violet filter material, either on the bulb or in a separate glass filter in the lamp housing, which blocks most visible light and allows through UV, so the lamp has a dim violet glow when operating. Blacklight lamps which have this filter have a lighting industry designation that includes the letters "BLB". This stands for "blacklight blue", which is a contradiction in that they are the type that does not look blue.