Black and light are two terms that do not go together when the meaning is taken literally. However there is a whole genre of black light bulbs in the lighting market. They have several specialized applications.
The use of black light bulbs makes things glow in the dark. There are two basic types of black light bulbs. Black lights available in fluorescent lights produce 100% UV energy while black light bulbs only emit a faint purple light. Black light bulbs are a popular choice for Halloween decorations. Black lights in fluorescent tubes for black light effects are also very popular for this purpose.
Black light fluorescent lamps contain a special element known as a phosphor. Upon being activated, a fluorescent black light bulb emits its UV energy. This energy is also referred to as UVA energy. Black light or "near ultraviolet" energy ranges from 310 nanometers to 400 nanometers in the electromagnetic spectrum. The human eye can distinguish energy only between 400 to 700 nanometer wavelengths. It is these wavelengths that cause the phenomenon of fluorescence, making the lighting provided by these bulbs attractive. In the range of about 370 nanometers, the radiation enters the visible range to produce a small amount of bluish light.
The black light lamp has found many uses in industry and home use as well. Black light uses in the industrial scenario include inspection for cracks, leaks, and other flaws during manufacturing and quality control checks. Used commercially, they have been found to be extrememly useful by cafes and night clubs for fluorescing costumes and decorations as well as for insect traps and psychedelic lighting. Another popular commercial use of black light bulbs is outdoor and indoor advertising, window displays, and theatrical and television scenery lighting.
Used by the police and other monitoring agencies, black lighting is used for identification and marking of objects, photocopy inspection, detection of counterfeit money and bank notes, petroleum geology, stamp examination, chemistry, embalming, luminous instrument panels.
Black light bulbs thus have varied applications that are both functional and ornamental.