Black light
The black light or black light (of the name of the inventor Robert William Wood), is a light made up of Violet and close relation Ultraviolet.
This light is absorbed and re-emitted in the form of visible light by the fluorescent substances , which they are artificial or natural (corals, for example).
The black light is often used to create esthetic effects in evenings, emphasizing the white. It is also employed in medicine for the diagnosis of certain pathologies, in particular in Dermatologie and Ophtalmologie.
The detectors of forgery banknotes use a small lamp producing of the black light. The black light puts in luminescence cotton and cellulose fibers. However the paper of truths tickets contains neither cotton nor cellulose and does not have normally to react to the black light. On the other hand certain tickets as the euros also carry impressions in invisible Encre to the natural light which become visible with the black light.
It is necessary to avoid using the black light too much in order not to suffer from ocular lesions due to the ultra-violets.
See too
- Detection of counterfeit bills per black light
Related articles
- Ultraviolet
- Lamp of invisible Wood
- Ink
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