It's a very common process in many industries, not just plastics. Many materials can be "doped" with "fluors" to either appear brighter (fabrics, papers) or to induce a more drastic wavelength shift. I have a container full of "whitening agent" that glows under UV illumination. I add it to mold release so mold coverage can be checked visually in a darkened room with a black-light. It can be added to paints & varnishes, coatings, etc., to give just about anything a UV response. If anyone remembers the "magic box" solar viewer in S&T a few years ago; I contacted the author of the article and we corresponded about using a doped projection screen to shift the wavelength of the solar image enough to see details normally out of the visual range. Neat idea. Now, as to the lanterns, I did state in my initial post that they best be used on cloudy or moon nights. Obviously noboby needs a bright lantern on a dark-sky night. Many of the new LED flashlights use the same LEDs, so the blue warning applies to them as well. But really, solar exposure near sundown is going to cause you more problems than a few minutes in the presence of a lantern. --- Jim Cobb <james@cobb.name> wrote:
From what I've read, I believe the frequency shift is done by the use of phosphors to cause fluorescence. ---- Jim Cobb james@cobb.name On May 28, 2004, at 10:43 AM, Michael Carnes wrote:
Back at my old club in Boston, someone gave us a talk about the technology of those lamps. In essence, much of the energy is shifted down from near ultraviolet (somehow). The light is quite strong in the blue spectrum, so you have to be very careful if plan on observing.
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