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Thread: Thermal Insulation of DPSS green

  1. #1
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    Default Thermal Insulation of DPSS green

    Hey guys. I have a 300mW Viasho green and it is a pretty decent laser. The problem I am having is thermal instability. The laser likes to be warm. Once warm, it performs beautifully with analog blanking and great output. If it is cold, the power output is horrible. Normally, before I run a show, I have to run the the green at full power for a few minutes to get the white-balance correct. The problem is, if the green is "off" for anything longer than 30 seconds, the power drops again and the white-balance shifts back to a violet white. I don't even have this laser mounted on an aluminum plate and there is no active cooling. *edit* by active cooling, I mean there is no forced fan cooling. I have no doubt that there is a tec in there.

    I was thinking about building a box around the laser that is lined with foam. I just want something that will keep the laser thermally stable for times when the green is not needed for 1/2 a minute or more. Obviously, it will cool if not being used for several minutes, but it is normally never off for that long during shows. I have tried to compensate with the software settings, but it is either too much or too little depending on what temp the laser is at.

    Any thoughts on insulating it? I don't want to cut the life of the pump diode by letting it get too warm.
    Last edited by absolom7691; 02-27-2012 at 05:33. Reason: clarifying
    If you're the smartest person in the room, then you're in the wrong room.

  2. #2
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    What model is it? any pictures?
    They did make some OEM types without TEC, I have one here that needs warming to perform and am investigating stability under modulation..
    A little bit werrrr, a little bit weyyyyyy, a little bit arrrrgggghhh

  3. #3
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    Not sure of the model number. The PSU is mounted in another part of the projector and hard to get to. I bought it last year. It's an OEM PSU with a large exposed heat-sink, not a labby. Here is a pic of the head, which probably doesn't help much.
    Click image for larger version. 

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  4. #4
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    Correction... it is a 200mW head, not 300mW
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  5. #5
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    I have some of those heads as well. Same problem.
    The solution is a bi-directional TEC controller.

    I am designing one and will make it when I find the time.
    BUT I will not be selling any, I don't want to go through all the trouble of mass producing / order processing / shipping

  6. #6
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    My 400mW CNI is like that too. TEC cooled yet it performs best after a minute of use. I really think the TEC control is not well adjusted...

    Output is best after a minute of use. I am not brave enough to mess with the adjustments...
    This space for rent.

  7. #7
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    Hmmmmmm, gives me something to think about. For the time being, I am going to try insulating it. If after about 10 minutes of use, I am going to see if the head feels warm. If not, I am going to run it full on for 10 mins and check again. If it is still not warm, I am going to run several shows and see if the output stays consistent. If not, maybe I will try *gulp* active temp regulating. Thanks for the input, guys!
    If you're the smartest person in the room, then you're in the wrong room.

  8. #8
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    It could be the KTP/Nd:YVO4 crystals heated by the 808 pump diode aren't up to temperature yet and cool down quickly. Heating the whole laser may not solve this ..

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