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Thread: 4kw Direct Diode laser cuts metal!

  1. #1
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    Default 4kw Direct Diode laser cuts metal!


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    mmmm love me some WBC'ed laser modules

    It is actually a pretty impressive result, they are almost to the power density of a modern (narrow linewidth, not WBC'ed) single mode diode at the fiber output, and significantly higher power density than what I have seen in any other commercial direct fiber system by nearly an order of magnitude, and are coming close to what the fiber coupled high power dpss systems provide

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    ... why 'first direct diode laser'? -- maybe 8 years ago I was involved into developing the justage-assembly for a 'ringfocuslaser' - http://www.ringfocus.de/en_page/prod...ringflaser.htm

    The complete module delivered 1.6kW on a spot of around 2 to 3 mm.

    Even then I was astonished by the unneded comlexity! - actually I could assemble a multi-diode-module with fibercoupled 9W@975nm-diodes, that will be of the size of a shoe-box and could deliver a power of rougly 1kW on a spot of 1mm diameter ... bigger box for more power ...

    Attached is an image of a pretty old (from around 1995) 'multi-diode-module' with 60 fibercoupled 350mW-diodes, emitting up to 20W@652nm out of a fiber-bundle with 0.7mm diameter!

    Viktor
    Attached Thumbnails Attached Thumbnails Diodenmodul 61x.jpg  


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    True, calling it the first direct diode laser to be able to cut metal is a bit of a stretch, although if you read 'cut metal' as 'cut at speeds comparable to existing CO2/DPSS lasers'...
    The selling point of this system is that it can deliver 4kw from a 0.4mm fiber with NA=0.1 (which, for comparison purposes, could be imaged to a 150um spot with a 17 degree cone half angle), compare that to your ring focus laser which delivered a 2500um spot size at 2kw at the same divergence--a power density some 250 times lower (if I didn't lose a factor of 2 somewhere).

    Even still it has a good deal of room to improve left, compare to one of these bad boys: http://www.us.trumpf.com/en/products.../trufiber.html 1kw into a single mode fiber, for the same 17 degree cone half angle you can focus to a spot size of 4um, a power density another 300 times higher still

    But if you really have money to burn what you want is one of the new femtosecond lasers, they are just starting to surface at 'industrial' power levels commercially, but there have been kW class femtosecond systems (based both on fibers and bulk crystals) demonstrated in the labs which offer the same perfect beams associated with normal fiber lasers and peak powers a million times higher for perfectly clean kerfs
    ex http://www.opticsinfobase.org/ol/abs...uri=ol-35-2-94 and http://www.lasermicromachining.com/d...20Applicat.pdf

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    Default Fiber bundling to knife-edge?

    In light of VDX's picture, I'm curious if there is any benefit to fiber-bundling multple red beams as oppsed to Knife-edge (lightshow use). Obviously, I don't think there would be much of a benefit until you start getting into lasers that have more that 4 diodes. I have always seen knife edge arrays as an alignment headache (perhaps because I have never built/owned one). I guess maybe a fiber bundle to replace this:


    I am sure I am going to get schooled here but that will quell my curiosity. Here is a *VERY* crude drawing of what I mean. Is this just a recipe for disaster?

    Click image for larger version. 

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    Thank you, Steve! I figured it was a fool's errand, otherwise people would be doing it.

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    knife edging is a lot cheaper.

    Quote Originally Posted by absolom7691 View Post
    In light of VDX's picture, I'm curious if there is any benefit to fiber-bundling multple red beams as oppsed to Knife-edge (lightshow use). Obviously, I don't think there would be much of a benefit until you start getting into lasers that have more that 4 diodes. I have always seen knife edge arrays as an alignment headache (perhaps because I have never built/owned one). I guess maybe a fiber bundle to replace this:




    I am sure I am going to get schooled here but that will quell my curiosity. Here is a *VERY* crude drawing of what I mean. Is this just a recipe for disaster?

    Click image for larger version. 

Name:	crudefiberbundle.png 
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ID:	44107
    suppose you're thinkin' about a plate o' shrimp. Suddenly someone'll say, like, plate, or shrimp, or plate o' shrimp out of the blue, no explanation. No point in lookin' for one, either. It's all part of a cosmic unconciousness.

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    ... 'normal' bundling of fibers gives a 'spot-array' as seen here:

    Click image for larger version. 

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    My idea was an array of 'pointed' fibers - either all focussed with a big, single lens -- or every with its own focussing lens ... this could be a GRIN-rod instead of a lens too - have some with different diameters from 0.2mm to 3mm and successfully tested the focussing abilities ;-)

    Click image for larger version. 

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    Viktor

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    We have discussed this concept here as well (and some of us have tried it). The approach that is available to an amateur is temperature tuning of a few diodes and then wavelength combining these to run co-axially. The articles I've seen in the past about this technique, replaces the rear cavity reflector of a long line of diodes with a dispersion element so that as you move down the line of diodes the wavelength of the output shifts steadily and precisely. This is practical because of the very wide gain bandwidth of these diodes. You then overlap these beams into a single, much more powerful beam with a second dispersive element. This paper is actually kinda fun to read:

    http://ieeexplore.ieee.org/xpl/login...mber%3D1516122

    I hope the link works.

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