Laser diode PSU

Discussion in 'The Projects Forum' started by Litch, Jun 12, 2014.

  1. Litch

    Thread Starter Member

    Jan 25, 2013
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    So I got my hands on some 40W diode laser modules (rather cheaply) in the hope that getting my DIY Laser CnC project off the ground. Originally I was fishing around for a CO2 setup but these were going cheap ($50) compared to similar powered CO2 setups ($500+).

    Anyway, the question I'm left with is: How do I power these things?

    Looking at this simplistically - they're just like LEDs. They have a forward voltage (typ around the same as a small LED, 1.5-1.7V) and are totally dependant on current limiting or they'll blow up.

    So, I'm looking for ideas, and I'd really like to have the ability to vary the current digitally (as to automate the CnC process for material width as well).

    The diode's parameters are as such:
    Operating current: 10/40/45A (Min/Typ/Max)
    Normal operating voltage: 1.6/1.71V (Min/Typ)

    The problems I'm faced with:
    * A 1.7V @ 50A power source?!? I figure I'm going to have to start higher with a 12V @ 10A source (for example - widely available) then use a second-stage DC-DC conversion down to the appropriate voltage and control the current from there.
    * How best to regulate current at that level? PWM? Would the above mentioned "DC-DC 2nd-stage" be the best place to do this?
    * Feedback for that current level? An integrated package or the old shunt and measure method?
    * Any circuits around that I provide a good example of where to start?
    * Pointers for dealing with such high current in PCBs?
    * Pointers for the overall project?



    Thanks in advance.
     
  2. shteii01

    AAC Fanatic!

    Feb 19, 2010
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  3. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Are there any left?

    Care to share the source?
    :)
     
  4. ronv

    AAC Fanatic!

    Nov 12, 2008
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    :cool:Ditto................
     
  5. RichardO

    Well-Known Member

    May 4, 2013
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    What wavelength is the LASER diode? The wavelength determines what you can cut.

    According to my notes:
    CO2 wavelength is 10.6 micrometers. Cuts and etches plastics and wood but not metal.

    Fiber LASER wavelength is 1064 nanometers. (1.064 um). Marks metal but works poorly on organics.
     
  6. Litch

    Thread Starter Member

    Jan 25, 2013
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    eBay was the source. Search for "laser diode" or dilas (OEM) and you'll eventually find one -they go like hotcakes if they're 'buy now' so you'll need to be quick.

    The diodes I have are 808nm, granted not ideal for cutting but the power makes up for that. I'll be able to prototype PCBs at least.
     
    THE_RB likes this.
  7. Merlin3189

    New Member

    Oct 20, 2013
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    <Q>RichardO = "The wavelength determines what you can cut."</Q>
    I don't know much about this, but would like to know more, so any reference you can give to read up about that?
     
  8. RichardO

    Well-Known Member

    May 4, 2013
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    I have considered building a "plotter" using a Laser diode in the 800 to 1000 nm range for cutting and etching acrylic and ABS. Unfortunately, I don't have any good information on the 808 nm Laser.

    Here are some clips from the Epilog Laser web site. Disclosure: I have some association with Epilog Laser.

    Note that the CO2 Lasers used in the Legend series vary from 30 to 75 watts of output power. A CO2 laser is only about 2% efficient --the input power of a CO2 Laser is something like 50 times the output power. A diode Laser is something around 30 to 50% efficient, I think.

    Epilog Legend Laser Series


    The Legend Series features our top-of-the-line CO2 laser systems and is utilized by customers for the highest-quality engraving and cutting of wood, acrylics, plastics, stone, and much more.





    Epilog FiberMark Laser Series


    The FiberMark Metal Engraving and Plastic Marking Laser Systems
    Fibermark Laser Technology
    Ytterbium Fiber Laser, Air Cooled, 1062 nm, from 10 to 50 watts.
    Marking and Engraving Materials:
    Most metals and plastics including: stainless steel, aluminum, black/white ABS, carbon fiber, polycarbonate, anodized aluminum, white PEEK, silicon wafers, colored delrin, magnesium, and much more.
     
  9. Litch

    Thread Starter Member

    Jan 25, 2013
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    7
    So I called up the Dilas reseller for pricing on a fibre coupled module for the diode I have; they didn't have such a module but had some exchange parts they would heavily discount (50W module) for me at around:

    ELEVEN AND A HALF THOUSAND DOLLARS?!?!

    Seems to me the ones on eBay must be dead - or near it to sell at a mere fraction of the price of a known-working second hand unit. In saying that, even if you can still pull a few watts of light out of the module still makes it a good buy.

    I guess I should stop wondering and hook up a power supply to one of these units - only problem is I don't have a CC power supply (and was looking to build one for it). If these modules are 100% fried, that kinda puts a spanner in the project's cogs and I'll be back on the market for any type of laser again including a CO2 type - the preference for cutting - which is totally incompatible when it comes to diode laser power supplies.
     
  10. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    At 40 amps typical operating current you can connect it to your bench supply and if your bench supply tops out at 3A or 5A current limit it definitely won't hurt the laser diode!

    It should still burn stuff at 3A or 5A, and will at least tell you if the diode is working.

    Be very careful with static, it's a good idea to have a 0.47uF polyester cap across the diode terminals. And don't connect live wires, make sure the power is off before you touch the wires.

    Please let us know how you go with the test! :)
     
  11. Litch

    Thread Starter Member

    Jan 25, 2013
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  12. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    Thanks for the ebay item info.

    Did you test the ones you already bought? It would be good to know yours work and are not duds, especially if someone else wants to buy.

    And is that the same ebay vendor you bought from?
     
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