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Thread: Correcting ld with pair prisms

  1. #11
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    well, i suppose so. looking the picture from right to left, it seems feasible.
    but wouldn' t it be too much fiddling?

    (assuming that diodes don' t shift wavelength over time etc etc)

    sausage time!
    "its called character briggs..."

  2. #12
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    why would the wavelength change?

    providing temps are kept the same the wavelength wont change.

    im not saying its the way to go, just say it works
    Eat Sleep Lase Repeat

  3. #13
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    Will try, still waiting for parts.
    I know this is a "dirty" setup but should be better than uncorrected beams. so IMO from best to worst:
    1-Correct r-g-b for each color, then overlap
    2-Overlap. Correct "white" with prism or Cylindrical. Re-adjust dichros to overlap again
    3-uncorrected at all
    isn't it?

  4. #14
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    The cylinders will probably be better in the long run and they are not that difficult to align. The reason prisms are used in pairs is to reduce the angle of incidence of each and this reduces the losses from reflection from the surfaces and this is because the reflective losses are not linear. Also, by adjusting the prisms you can compensate the deviation of the first with the second to achieve a parallel input and output beam.

    Now, I'm going to nudge you here. You should try the experiment. Can you eliminate the need for dichroic beam combiners?

  5. #15
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    There is an optic to combine RGB beams without dichros I believe. Adam (Buffo) had one years ago .. finding that pic/ post from 2007 would be damn near impossible .. I don't know what the gadget is called .. could be a tri-facet prism of sorts .. 3 beams in, one beam out..

  6. #16
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    Interested in 6-12W RGB projectors with low divergence? Contact me by PM!

  7. #17
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    Wow reading that thread brings back memories. Back when Spec used to post a lot ..

  8. #18
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    I don't think that is what you want and that's not what I mean. Entering a single or a pair of dispersing prisms at several angles for several wavelengths is more elegant. That device looks more like a cemented three color prism combiner.

  9. #19
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    I thought the firewall at work blocked the pics but came home and seems that the pics are no longer here. That 1 pic wasn't what I was referring to .. I'll see if I can find it ..

  10. #20
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    Well, with the help of some very awesome folks here on chat-- they found it .. Adam's photo of the whitelight trichro .. yep.. that's an argon and looks like a hene too :]
    Photo circa 2002 -- One of the most memorable photos I've ever seen ..
    Gallery Forum Members Buffo's Laser Gallery Fujinon Trichro (Poor man's whitelight!) This is what it's supposed to look like when it's aligned correctly. (Ye, the CD-R under the Argon laser is a shim!)
    Click image for larger version. 

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    Eric, I know that this is not what you were referring to .. but just had to post it anyway
    Last edited by steve-o; 05-29-2014 at 04:49. Reason: deleted 3d post

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