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Thread: LPC 826 658nm diode tests/infos

  1. #31
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    You have got to be kidding. There are all kinds of threads on this forum from the sophisticated to the-Guess what I did last night with a board and some glue. But as soon as we start discussing the merits and methods of cooling then its pointless unless we are prepared to consider Invar base plates and adaptive optics. Consider the difficulty in simply achieving best focus. I mean really best focus. By hand adjusting a tiny lens and estimating the far field sharpness or spot size/shape you are working with much larger errors than those introduced when you cool a monolithic aluminum base plate by 50C. It all is relative. The larger the cooling the greater the potential gain and the more complex the set up. Even in my TEST module (at -55C actually) the only consideration beyond inexpensive foam board was the warming of the optical window with a couple of resistors to eliminate condensation at the very lowest temps. To keep things simple, I am running the projector at -30C and therefore the less blue shifted 645-647nm emission. The weight of the projector is derived mainly from the enclosure/breadboard at aprox.60 Kg. There is no argon, CVL FEL or rail gun within.

  2. #32
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    Quote Originally Posted by planters View Post
    You have got to be kidding. There are all kinds of threads on this forum from the sophisticated to the-Guess what I did last night with a board and some glue. But as soon as we start discussing the merits and methods of cooling then its pointless unless we are prepared to consider Invar base plates and adaptive optics.
    Sorry to be missunderstud, I can't recall using the term "pointless". On the contrary, im allways interested in new tech. approaches to the issus that arrise in multi diode systems. Some pictures would really be nice.

    With your 100kg projector (is it just a projector or a laser bank)...I mean my sandwich build gas powerd laser bank with 2 breadboards @ 1450mm x 450mm x 10mm didn't weigh that much. Weight was the major reason for switching to solid state lasers. If I were you I would be majorly working on weight reduction.

    cheers!

  3. #33
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    With your 100kg projector (is it just a projector or a laser bank)...I mean my sandwich build gas powerd laser bank with 2 breadboards @ 1450mm x 450mm x 10mm didn't weigh that much. Weight was the major reason for switching to solid state lasers. If I were you I would be majorly working on weight reduction.
    Yes, but did your sandwich built large frame argon bank produce 10W of red alone and could it run single phase from the grid?

    The huge advantage here is that we're finding out a method to make the kind of red we want (powerful 640'ish) and it's an approach that scales. Furthermore, I'd rather replace an LPC826 (or even have an in-module hot spare) than having to splurge another $200 for a new 642 diode.

    I'll see if I can salvage a TEC and a PBS somewhere and have a shot at a dual 650+nm/642nm setup. That way you can profit from the brightness of 640 wavelengths, yet still have the colour gamut from 650nm.

  4. #34
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    Quote Originally Posted by Stoney3K View Post
    Yes, but did your sandwich built large frame argon bank produce 10W of red alone and could it run single phase from the grid?

    The huge advantage here is that we're finding out a method to make the kind of red we want (powerful 640'ish) and it's an approach that scales. Furthermore, I'd rather replace an LPC826 (or even have an in-module hot spare) than having to splurge another $200 for a new 642 diode.

    I'll see if I can salvage a TEC and a PBS somewhere and have a shot at a dual 650+nm/642nm setup. That way you can profit from the brightness of 640 wavelengths, yet still have the colour gamut from 650nm.
    So far this is all just an interesting subject for discusion, but a succesful, stabil 20 diode build, set out temperature deltas of 60C°, still remains to be seen. Just looking at planters 20 diode build, it just screems out allignment issues. I just hope he never has to move it.

  5. #35
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    I am the first to agree that the laser modules that I built are not easily portable. Just a couple of days ago, I spent an hour moving the lasers and the control cart across the room ( 100 kg and lots of tubes and wires), but portability was not a primary consideration. This is more of a powerful tabletop laser built to study the issues involved with extreme cooling to which I added a scanner. If the intent is to construct a portable projector and knowing what I know now I would set up a smaller number of diodes in a more conventional horizontal array, but I would mount each separate diode/lens module on a powerful 2 stage TEC,cover the module with a monolithic foam block and seal the output aperture with a small heated window. An easily replaceable $10 diode that is just as bright as a $200 diode is too attractive to pass up.

  6. #36
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    well, i have to admit i have not given up on the idea myself

    i was able to cool a foam insulated alu block down to -3 using just a 12v / 5a tec cooled with a large heatsink and a 12cm computer fan

    now i have 2 12v/10a tecs and i am waiting for a 12v/29a psu to fire them up. i have dug out an AMD athlon xp waterblock, i also found a 12v 500gph pump, so i plan to run both tecs experimentally using the pump, a bucket of water and icecubes, just to see how low i can go

    my goal, after i learn enough on cooling diodes, is to make a quad or 6 red, get as close to 640nm as possible and keep it fairly small to fit into a projector. for the time being, i am just cooling pieces of alu whenever i find the time. have not chilled a diode yet
    "its called character briggs..."

  7. #37
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    Don't give up, but I would modify your approach to keep it simple and at the same time make it work better. Do not bother with cooling the hot side of the heat sink below room temp. This just creates a mess with condensation. A water cooling loop with a remote radiator can be small and is VERY effective at extracting a lot of heat. Max out your TECs;two stages are better than one. A nice compact set up if running multiple modules is to buy just one type of TEC and run the first stages in parallel and the second stages in series. This eliminates the pyramid effect and makes mounting easier ( at the expense of a small amount of efficiency). Oversize your diode module block to allow for retaining screws to compress the TECs and insulate around the edge of the TECs and under the edge of the module to prevent condensation. If you use plastic retaining screws you can electrically insulate the diode and this allows the convenience of series operation ( which I could not do ). Good luck!

  8. #38
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    pyramid effect... what can this be? i have some studying to do

    thanks for the tips mr planters


    @ anybody: is there some evidence that a tec running of a contoller gets bette efficiency than a tec that is just pluged into a psu feeding it the necessary power?
    do tecs peform better when under pwm modulation, or any dc curent "waveform" would do?
    "its called character briggs..."

  9. #39
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    Most commercial multistage TECs use progressively smaller modules for subsequent stages ( more like a Ziggurat ). Don't bother with a controller, even a switching PSU is just fine. These TECs are basically self limited resistance loads. Just size the PSU ( DC of course) voltage to match the input spec of the TEC. Its that simple.

  10. #40
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    Quote Originally Posted by LaNeK779 View Post
    @ anybody: is there some evidence that a tec running of a contoller gets bette efficiency than a tec that is just pluged into a psu feeding it the necessary power?
    do tecs peform better when under pwm modulation, or any dc curent "waveform" would do?
    You will only need a controller if you want to keep the temperature at a specific setpoint. This is important for DPSS modules, where the crystal has a specific peak of operating efficiency, but for diodes, you can just get away with rated voltage and all of the juice you can give it.

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