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Thread: loss from a dichroic mirror

  1. #1
    Join Date
    Nov 2014
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    mid michigan
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    Default loss from a dichroic mirror

    I have a dichro that reflects red very well and was thought to pass green and blue but i find that the dichro reflects almost half the power from my green 532nm laser, it's 25mw so losing 10mw from the dichro reflecting that away seems off, i don't have that level of loss on my other ones
    Polk SDA SRS, Parasound HCA 3500, Luxman M117, Onkyo 504, 7.62X39, sometimes a ball on a string is the greatest of toys for us nonhuman types. oh and some lasers, lots of lasers

  2. #2
    Join Date
    Jul 2006
    Location
    Connecticut, USA
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    2,478

    Default

    1- are you SURE you're losing 'half' of your green? If you are guessing that just from site, chances are you are incorrect. In CAN be very deceiving seeing the reflected waste beam. I agree with you on that. But chances are, you are probably only losing 5-10 mw.

    2- what type of dichro is it? If it's a "cheap" one or not a high efficiency one, than the transmission rate is usually around 95% or less. So a 5% (or worse) loss or back reflection is to be expected. This equates to about 10mw or more.

    3- try to keep the filter as close to its AOI (angle of incidence) the best you can. This is usually 45 degrees. There are filters out there that perform considerably better at weird AOI's. But chances are, you should be at 45 degrees.

    hope this helps.

    -Marc
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  3. #3
    Join Date
    Nov 2014
    Location
    mid michigan
    Posts
    792

    Default

    Sorry for my late reply, I am using a power meter to get the numbers on the loss so about a 9 mw loss, it's an older lab laser so it has a good stable power but lower power, 25mw at rated, i have gotten 90 with mods.
    the dicros came out of the light engine from a sony LCoS projection tv, the reflect red and pass green is the only one out of whats in it, the last stages where i thought reflect red and pass all, it reflects the red very nice. they are at the 45 degree angle, i guess i will need a different dichro , in the tv the green was just terminated on the black housing, since they used 2 yeash mush habe been made to pass about 50% and with the twp removes most of the green. the usable dicros in these area large, i could cut maby 4 standard size dichro
    Polk SDA SRS, Parasound HCA 3500, Luxman M117, Onkyo 504, 7.62X39, sometimes a ball on a string is the greatest of toys for us nonhuman types. oh and some lasers, lots of lasers

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