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ArcticMyst Security by Avery

Best diode for efficient laser cutting

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Mar 29, 2012
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It's been a while since I've made a laser (last one was your typical M140 445nm C6 host). But I'm working on a side project now, I'm building a mini laser-cutter! I was wondering which diode would be the best for doing a lot of cutting, at a low duty cycle. My first reaction was a 12x BluRay burner (like the one available at DTR's). This is for several reasons-
  1. Superior beam divergence
  2. Better absorption rate
  3. Higher frequency = less dispersion
  4. Better duty cycle
I was wondering if this would be the best choice then? My only worry is at what current I should run the diode at. Too high, and I'll have to put some more serious contemplation in heatsinking, too little, and I feel it wont burn at all. I have no experience with BluRay burners, so will 500mW of focused 405nm light compare with 1500mW of unfocused 445nm? Or would another diode be better suited for my needs.

Thanks!
 





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What are you trying to cut??

Well, to be perfectly honest, I guess my answer would be 'as much as possible'... But I realize that is a really vague and unhelpful answer. Wood engraving is the definite must-have, but that's pretty attainable (my 95mW green can do that). I would like to also be able to cut through some foam, or something sturdy enough to use on other hobby projects. On the upper-end of power, I would like to be able to cut through plastic like in cd-cases too (the black side of course). Do you know if that is possible with a 12x BluRay @ 400mA? Or, what current should I run it at for the best tradeoff of effectiveness and lifespan? My 445nm seems not to be able to cut through cd cases too easily, but I know they aren't fair comparisons due to the different beam specs.
 

Things

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I've used 445nm on a laser cutter before, and engraving on wood is definitely doable. I've also cut paper of various thicknesses, and some foam. I would say it could cut thin plastic like CD cases too, but it'd be pretty slow.

In terms of 445 vs 405nm for this, well, I couldn't say, however the 405 will give you better accuracy.
 
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I've used 445nm on a laser cutter before, and engraving on wood is definitely doable. I've also cut paper of various thicknesses, and some foam. I would say it could cut thin plastic like CD cases too, but it'd be pretty slow.

In terms of 445 vs 405nm for this, well, I couldn't say, however the 405 will give you better accuracy.

Okay thanks. What mA were you running the 445 at? Yeah, I think a 405 is better suited because of the increased 'resolution'. I mean... it's used to right on discs!
 
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i would think a 445 laser at say 2W is the ticket here. if you focus it way in, the beam waist is very tiny with a hella power density. distance from whatever you want to cut is critical here tho. with good heat sinking and/or active cooling you could have an unlimited duty cycle. you would also need some air flow to keep the smoke away from the lens.
 
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i would think a 445 laser at say 2W is the ticket here. if you focus it way in, the beam waist is very tiny with a hella power density. distance from whatever you want to cut is critical here tho. with good heat sinking and/or active cooling you could have an unlimited duty cycle. you would also need some air flow to keep the smoke away from the lens.

I guess 9mm would be the best choice then, considering the heat dissipation. I'm planning on having it only be around 2 inches from whatever it is cutting. Duty cycle was my only worry with a 445 - you think I could get 100% with only using heatsinking? And what do you mean by active cooling - something like TEC or just a fan?
 

DTR

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A large finned sink with a fan would probably be enough. That is how they run them in the projectors they come out of and those are in continuous operation with 12 diodes per block all going at once. Although they do run them at lower currents than we typically do.:beer:
 
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A large finned sink with a fan would probably be enough. That is how they run them in the projectors they come out of and those are in continuous operation with 12 diodes per block all going at once. Although they do run them at lower currents than we typically do.:beer:

Okay - another problem I have is that I don't know if my mount will be able to take the weight of a larger heatsink (I'm using cd drive steppers). Worth a try though - I have some old CPU heatsinks I'll try to repurpose.

Oh and DTR - I visit your shop pretty often to see if there are any new easily accessible diodes out there, and everytime I see those 5W red C-mounts, my heart skips a beat... until I remember I'm a broke college student. Maybe one day...
 




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