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Thread: Modulation efficiency

  1. #111
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    I may be mistaken, but it it looks like the color safe is just a few photodiodes and some feedback circuitry to adjust the input to the modulation input on the laser laser to match the desired output, and doesn't do the actual modulating of the beam. This is of course different from the AOM/PCOAM which is designed to have the laser run at full power, and the aom is what actually modulates the laser power.

  2. #112
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    The IRIS colorsafe system would eliminate the need to use any form of external modulation with solid-state lasers, but the system is quite expensive last I heard. Any innovation in the internal functions of the laser sources themselves would be the ideal solution, and I think the best hope for that right now is hybrid gain mediums.
    Last edited by ElektroFreak; 12-12-2009 at 08:20.

  3. #113
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    Quote Originally Posted by krazer View Post
    I may be mistaken, but it it looks like the color safe is just a few photodiodes and some feedback circuitry to adjust the input to the modulation input on the laser laser to match the desired output, and doesn't do the actual modulating of the beam. This is of course different from the AOM/PCOAM which is designed to have the laser run at full power, and the aom is what actually modulates the laser power.
    Yes, but when you set the laser at 50% colorsafe makes sure the laser is outputting 50%. So you laser will be complete liniair and perfect modulation.

    Thats where topic was about right? not aom's

  4. #114
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    mccarrot, take a look at post 64: http://www.photonlexicon.com/forums/...3&postcount=64

    To the best of my knowledge, the iris colorsafe is a combo, part scan fail, part optical feedback loop. The optical feed back option is discussed rather heavily in this thread and I think one of the best solutions so far was a hybrid optical feedback loop/AOM system for the best possible modulation.

  5. #115
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    The colorsafe system would eliminate the need for an AOM completely. It would seem that it provides exactly what this thread is discussing, albeit at a high price.
    Last edited by ElektroFreak; 12-12-2009 at 16:02.

  6. #116
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    The colorsafe system would eliminate the need for an AOM completely.
    Hmm, are you sure? If it's nothing more than an optical loop back to the driver, I don't see how it could be all that effective unless you already have a very stable laser. And I have yet to see a stable 473nm laser!

  7. #117
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    I'm only basing that on their claims. In all honesty, the real world performance could be quite different from what they claim it to be. I would assume they have some innovations involved that we wouldn't have any detailed knowedge of.

  8. #118
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    The manual offers some interesting reading: http://www.eyemagic.gr/laser-downloads.html

    I like that they have the color delay/gain/offset on the main driver card. It does appear that the modulation signals connect to the driver, then out to the laser drivers. So there doesn't seem to be anything fancy in there. There's no doubt that a feedback loop would work well to improve linearity, however if the laser is wildly unstable, then there's just not much that can be done I suspect. If you're 100mW blue laser is receiving a 2.5V signal from your DAC and it's only putting out 20mW, all the feedback loop can do is add 2.5V to the modulation line until it gets to 50mW. Which may not occur in time.

    If anything the offset makes a huge difference, it did on my projector. And the delay helps clean up color tails. I suspect they may use a variant of Bill's Sallen Key filter design. I know I do, and proud of it!
    Attached Thumbnails Attached Thumbnails DSC00278.JPG  


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