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Thread: cni laser driver pot adjustment

  1. #1
    Join Date
    Jul 2007
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    west sussex uk
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    Default cni laser driver pot adjustment

    hi anyone know what the pots on a cni laser driver arie, which does what
    my cni is running 152mw and should be putting out 200mw so needs a tweak, postage both ways to cni is to high so i might give it a go myself
    any advice here is wellcome

  2. #2
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  3. #3
    Join Date
    Jan 2007
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    Sheepsville, Wales, UK
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    3,396

    Default

    Chris
    As pointed out by 4d on the link you should monitor the current by reading the volts across the 0.33r resistor. I would go by the current NOT the output power. Measure the current before tweaking anything. The problem is that you wont know what the max you can go to is but as a rule of thumb 1W pump diodes will go upto about 1.2A and 2W to 2.6-2.7A. If you measure before you adjust and see its above 1.2A then you can assume that the celing is gonna be over 2A.
    Also an idea would be to check your TECs you may get more power and stability by adjusting these. Adjust one at a time by small amounts, note how far and which direction you have gone and let the laser stabilise for a few mins. Its slow and dull but rewarding if you get more power without leaning on the diode! If you have access to a scope you can put a photodiode in the beam and measure the noise on the diode from the scope - sometimes its better to get less power with low nose than more power with lots of noise. The noise will manifest in the scanned beam as the famous 'jelly beans' Green will do it less than blue but will still do it. Also a good tip if you can temp tune with a scope is to do it while the laser is being modulated that way its more of a real world scenario. I know however this may be a prob at the moment cos some buggers got your DAC
    Rob
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  4. #4
    Join Date
    Jul 2007
    Location
    west sussex uk
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    2,279

    Default cni tuning

    this sounds to complicated for me to do i think, i will play safe and send it back to lasershow parts for a tune up
    thanks anyway guys.

  5. #5
    Join Date
    Jul 2007
    Location
    west sussex uk
    Posts
    2,279

    Default fixed my cni 200mw

    fixed it
    it turned out to be the power socket on the laser driver board when you touched the 5v power plug thats on the board the power went up to 195mw so i desoldered it off the board replaced it and works ok now , somehow the socket was not letting the driver have full 5v??

    thanks for the info four-dee tweaked up diode drive to 210mw

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