Archived posting to the Leica Users Group, 2001/07/31
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Henning writes: > Apparently it's in the UV range. UV is blocked by the phosphor coating, for the most part. After all, it's the UV that makes the phosphor glow, when the phosphor _absorbs_ it. Additionally, the UV is produced by ionized gas in the tube, not by the phosphors (normally), which necessarily reemit at a longer wavelength than they receive; so UV should be present only when the lamp is on, and if it gets out at all, it gets out through the ends of the tube, unless the phosphor blend in the lamp happens to reemit in soft UV (hard UV is unlikely, as that is what the tube produces internally). Finally, normal tubes are made of glass that doesn't transmit short hard UV light at all (germicidal lamps are one exception, as they are made of special glass and contain no phosphors, so short--and hazardous--UV light blasts right out of the tube, by design). The easiest way to be certain is to conduct a test, but a flat statement that all fluorescent lamps must be avoided is simply incorrect.