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Thread: pl 520 and stand-by beam suppression

  1. #1
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    Default pl 520 and stand-by beam suppression

    I have the issue that then I activate "stand-by beam suppression" on a pl 520 it seems to need ~100micro seconds to wake up from idle.
    This can be seen on various test-pasterns and graphics. When a white beam goes on from being blanked, the green needs considerable more time to recover than the PL450B and HL63603TG. Making the beam magenta for the first 3 points.
    When sbs is disabled everything works as a charm. ( But to achieve some lineairity, I need to add some bias, which in turn adds an annoying beam when it should be off.)
    Did anybody find a solution for this? (I'd rather not install a shutter)
    Can I remedy this by applying a sub-threshold-bias current ?



    Other thing I noticed, lasing threshold is pretty sensitive to temperature.
    Funny, because I didn't noticed it before, and I don't recall having read about it here on the forums.
    Maybe it's because dpss modulates like a wet towel, all red and blue diodes seem to behave perfectly in comparison.
    Since green diodes has the promise of perfect modulation, I may be hyper critical on all modulation characteristics, expecting a ruler-flat response also when I lower the intensity of my projector to 10%.
    I guess I have found another good reason to tec my diodes.

  2. #2
    mixedgas's Avatar
    mixedgas is offline Creaky Old Award Winning Bastard Technologist
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    Take a look at the compliance range of your driver on a scope, if you can. I suspect something else is afoot and its tied to the diode electrical characteristics vs the driver transfer function. The PL data sheet says 1 nS risetime.

    Steve
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  3. #3
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    I see PL 520 datasheet specification for >100MHz, but it says nothing about the waveform or depth of modulation so I can't make any inference of 1ns, only that it should be better than 10ns, and maybe if you're accepting a rough sloping ascent at that. Where does that 1ns figure come from? I got my datasheet from ProPhotonix, an official Osram distributor, and can't find anythign later than their 'preliminary' datasheet. I imagine Osram would see to it that an official distributor had the latest data...
    Last edited by The_Doctor; 09-01-2013 at 17:35.

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    what dichro are you using to mix the diodes? I could not find one to work. can you post some images so we can see the modulation quality. I have been waiting for drivers so I never got to see how well the three diodes modulate together. My hope is they are as good as pcaom.

  5. #5
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    Quote Originally Posted by kecked View Post
    what dichro are you using to mix the diodes? I could not find one to work. can you post some images so we can see the modulation quality. I have been waiting for drivers so I never got to see how well the three diodes modulate together. My hope is they are as good as pcaom.
    What didn't work for you I used standard OSLS dichros with no issues.

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    Quote Originally Posted by -bart- View Post
    (I'd rather not install a shutter)
    install a shutter

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