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Help with optics

  1. Apr 5, 2009 #1
    Hello everyone,

    I senior working on my undergraduate in ME. I am building a advanced weathering machine for my senior project. I am currently having two problems related to optics

    1) For the device I am testing I need to bath it in UVA-340. The lighting on the object must be uniform (i.e. no bright spots). I am having a hard time finding information on how to achieve this. I cant for the life me, find the correct permutation of words to type into google to find information on how to do this. If someone could point me in the right direction it would be very useful.

    2) Also, if possible does any body know of any technical glass or plastic which transmissive UVA-340 radiation well. I known that normal glass does not transmit much UVA. Obviously quarts would work but it is way to expensive. I was thinking about using the plastic which tanning beds are made out of but I do not know what that material is. I found a few web sites which refer to it as an acrylic but does not give me much to work with.

    Any help would be greatly appreciated.

    ps. not sure where this question should go so i filed it under general, please move if necessary
  2. jcsd
  3. Apr 5, 2009 #2
  4. Apr 5, 2009 #3

    Andy Resnick

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    "UVA-340", I assume, refers to ultraviolet light in the A range (which is 400 nm–320 nm).

    If you absolutely need 340 nm light, you may have a problem: commercial blacklights operate at 365 nm, germicidal bulbs are around 250 nm. You would need a Xenon arc and a 340 nm filter, making your application impractical.

    If you can use a blacklight, hanging the bulb in a mirrored box will provide very good uniformity. If the part(s) are small, you could put the part in an integrating sphere and then the 340 nm band becomes accessible.

    I'm not sure what is very transmissive at 340 nm acrylic appears to:

    http://www.hydrosight.com/technology/acrylic_uv_resistance.php [Broken]
    Last edited by a moderator: May 4, 2017
  5. Apr 5, 2009 #4
    Actually UV grade fused silica is quite transmissive down to even 160nm.


    Roughly ~90% i think without looking too much into it. Windows linked from the page above aren't too expensive (unfortunately this is untrue for most optics.

    As Andy R. said above you might be able to get by with a blacklight source or even a UV diode(not sure about price and wavelength but lowest i saw was 375nm) and diffusing plate to spread the light. The ideal thing would probably be a Xenon lamp in a monochromater source if you really need ~340nm but both bathing an object in the light from it and the price would be problematic.
  6. Apr 5, 2009 #5
    I'm curious, why do you need λ~340 nm? Do you need the 3.65eV photons or can you possibly use a lower energy photons and make it work? This coupled with a diode/blacklight would probably be the easiest method if you can make it work.
  7. Apr 6, 2009 #6
    Thank you VERY much. I picked UVA-340 because that is the same wavelength that Q-labs uses in there UV weathering test machines. I need to finish a another report for a different class right now, but i will get back to this soon. Thanks again, very helpful.
  8. Apr 9, 2009 #7
    Thank you very much. I ended up choosing an UV acrylic which is fairly easy to get and dirt cheap compared to Fused Silica..........an used acrylic sheet from a broken tanning bed.

    Thanks again for the help. :)
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