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Thread: Working with laser below zero degree

  1. #1
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    Default Working with laser below zero degree

    Hi friends,
    I'm designing a 25W RGB laser projector and I'm thinking about the working temperature

    It is knowed that the best option is to work below 20C to obtain best results, best lifetime, but what happen when the temperature of diodes is below zero e.g. -15C

    The datasheets of some laser diodes says "Operating Case Temperature 0 to 60C"

    Taking it in account, would I need to heat the inside of the laser?

    Hope someone can help me
    Last edited by francisco; 08-09-2018 at 04:15.

  2. #2
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    ... better heat it to something like 12degC or more - condensing water and ice on the optics could cause some problems ...

    Viktor

  3. #3
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    Thanks Viktor
    Do you know if the outdoor lasers has a heating system inside? I never saw it but I would like to learn a bit more

    Francisco

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    ... this was/is common for old ones and "good" actual types, meant for outdoor-use under harsh conditions or with high ambient humidity ... haven't seen this with modern "consumer grade" devices ...

    Viktor

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    Put diodes in sealed box and fill with dry nitrogen. Heat an ar window where lasers exit, resistor should be plenty

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    Put diodes in sealed box and fill with dry nitrogen. Heat an ar window where lasers exit, resistor should be plenty

  7. #7
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    Quote Originally Posted by kecked View Post
    Put diodes in sealed box and fill with dry nitrogen. Heat an ar window where lasers exit, resistor should be plenty
    Thanks Kecked, I didn't know the boxes of RGB lasers was filled with nitrogen! good information

    Francisco

  8. #8
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    Quote Originally Posted by francisco View Post
    Thanks Kecked, I didn't know the boxes of RGB lasers was filled with nitrogen! good information

    Francisco
    They usually are not. Just saying thats a way around the condensation issue. Beside a little color shift, the diodes are very happy when cold. Its the water vapor making ice that is the issue or in the least fog blocking up the optics. Dry air or nitrogen or whatever keeps the moisture away. Keeping in box keeps the water out. Problem is then limited to window lasers exit. You need to warm that a little to prevent condensation and hence fog or frost. It is not enough to just pump dry nitrogen into the enclosure. It needs to be totally sealed.

  9. #9
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    mixedgas is offline Creaky Old Award Winning Bastard Technologist
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    Use Dry nitrogen with silica gel dessicant packs. Have Heated AR coated windows. You'll need to potentially heat any DPSS.
    ~
    I've done outdoor laser shows with Ion systems below freezing. We at least had a elevator room to put the heads in when off. With SP 165s,that required immediately injecting antifreeze into the system when off and dashing into the building quickly. You may need pure alcohol to get condensed water off things like beam table mirrors.
    ~
    Antifreeze finds its way to the optics and is sticky.
    ~
    ON very cold days there is no humidity or dust in the air, so you'll need fog machines. Our show was very disappointing when had no fogger and cold air.
    ~
    Most large blue and green diode can windows, as well as some single mode reds, are not hermetically sealed, so water condenses on the back side of the can window... Ask me how I know.. :-( I've tried to clean a few, and they often leak!

    Ste
    Last edited by mixedgas; 08-14-2018 at 16:27.
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