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Thread: Blue eBay diodes - 5.6mm vs 9mm laser diode case - heat efficiency

  1. #1
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    Default Blue eBay diodes - 5.6mm vs 9mm laser diode case - heat efficiency

    Assuming i took a 1 watt laser diode die that performed happily in a 9mm can, and put it in a 5.6mm can, and cooled the diode with the same size TEC/heatsink etc, would i expect a much shorter lifetime given the smaller can ?

    This is in reference to our suspicion that the ebay diodes were actually 1 watters in 5.6mm dies, removed from the 2500 lumen casio projectors. (as opposed to the 2000 lumens using 500mw nichias).

    Basis for this theory ? similar beam specs and thresholds to our sample 1 watt nichia.

    It would make me feel a little better about buying the ebay diodes if i could comfortably run them at or closer to 1 watt than 500mw.
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    What does the beam output look like on your 1 watt diode. I have a feeling that these are custom designed for lots of optical out and for the intended use a nice small beam isn't necessary. These have a large emitter area.

    As for the thermal, I would imagine that it is harder to extract all of the heat out of a 5.6 but at 600ma and 460mw with a small tec things seem to be stable.

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  3. #3

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    The difference between a 5.6mm/9mm can isn't that huge (in fact, with good heatsinking there is no reason you shouldn't be able to run at 5.6mm at as a high a power as a 9mm--remember the die inside is only 1-2mm^2 to start with!).

    But you aren't suggesting someone is going to remove a die from a 9mm can and put it into a 5.6mm one are you? Laser diodes don't work that way, it would be like removing a pentium die from the pcb with all of the pins and moving it to a different carrier, not a fun prospect. Its it however entirely possible they ordered dies normally sold in 9mm cans in a 5.6mm can to save space.

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    heat transfer is limited by the die surface on the base of the can, so if you keep a contact surface greater than die contact surface, it should do (the 5.6 can is enough I think, but you have to limit thermal inertia, ie put it in a small block with a TEC at least the dimensions of the block, and stable thermal loop)

  5. #5

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    just my view here-

    if you have the money and want to be 100% safe then buy a proper module/diode.

    if not then pay £40 and get a diode that runs at 500mw, if it pops after 6months buy a new one and turn the power down a bit.

    its amazing that these diodes are now cheaper than 642nm diodes. even if these 445 diodes can only run at 300mw excellent im mega happy.
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    Quote Originally Posted by aijii
    our suspicion that the ebay diodes were actually 1 watters in 5.6mm dies, removed from the 2500 lumen casio projectors. (as opposed to the 2000 lumens using 500mw nichias)
    That certainly explains the difference in threshold

    Quote Originally Posted by chad
    I have a feeling that these are custom designed for lots of optical out and for the intended use a nice small beam isn't necessary
    Either that or rejected production ones that didn't quite make specification

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    Quote Originally Posted by p1t8ull View Post
    Either that or rejected production ones that didn't quite make specification
    If each beamer contains 24 diodes then they would need a lot of rejects

    Assuming this is true and the 2500 lumen beamer contains custom 1W diodes (higher power in same casing with as downside worse beamspecs) and the 2000 lumen model contains “original” 500mW nichia’s. Isn’t the 2000 lumen beamer a better donor device for our purpose then?

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    You would think so, as the stripe would be smaller, and the divergence less.
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    who said anything about "worse" beam specs ? The 5.6mm ebay diodes have similar beam specs to our 1watt nichia in a 9mm can.

    My theory is that casio requested the higher power die in a 5.6mm can so that they could use the same hardware around the laser diodes in the 2500 lumen unit. save on manufacturing and they could use the same diode mounting assembly for the 2000 and 2500 lumen units.

    after all - when we probed the ebay seller about the similarity in specs to the nichia 1 watts, he didn't exactly say they aren't 1 watt. just that you need to be careful to cool them properly but they should be good for 1 watt. he also wouldn't come clean on where they came from...

    Simon: the rejected from production theory was all good and proper before the Casio video projectors came to light. I like my theory better I mean who would have thought we'd see so soon a source for 24 diodes for around 1KUSD ?
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    Quote Originally Posted by SrS View Post
    Assuming this is true and the 2500 lumen beamer contains custom 1W diodes (higher power in same casing with as downside worse beamspecs) and the 2000 lumen model contains “original” 500mW nichia’s. Isn’t the 2000 lumen beamer a better donor device for our purpose then?
    hmm. 24 x 1 watt diodes, knife edged, and mixed with a laserscope
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