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About home lasers

lugnut

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Hello there!

I am very new in the field in lasers, and have vary little knowledge of them, and I would like some help.
I am working on (paper) project, in which I will need a laser that a focus in the region of 1/10mm to 1/100mm,
and has an instant heat of 240-260 degrees Celsius. (Melting point of polystyrene)
it also needs to be small and light.

I have read that some are using lasers from DVD burners, and "tuning" them to desired specs. Is that something that I can/ should do ?
Or if not, then what ?
At this point, I am not so concerned if it is a DIY job, or an off the shelf laser, both are fine.
 





lugnut

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Thank you!
Maybe latter I will, but right now, I am trying to figure out how "popular" the lasers are, and what the price range is.

"IF this was in production, how much would it cost..." - is my thinking. :)
 

lugnut

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Oh, its not foam, its a powder.
The project is about a rapid prototyping machine.
The actual element that "makes" the prototype, is a laser that melts the plastic powder, and thereby bonds it together to create the item.
 
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lugnut said:
Oh, its not foam, its a powder.
The project is about a rapid prototyping machine.
The actual element that "makes" the prototype, is a laser that melts the plastic powder, and thereby bonds it together to create the item.
Oh... Now i see.
 

lugnut

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So, can you help me then ? :)

can the homemade lasers be small enough to project onto a 1/100mm ?
can they be made to burn at 240 degrees Celsius ?
Price ?
 
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All that depends.  The polystyrene powder is probably white, so it may not absorb visible light, like the red laser light, very well.  You may have to use IR or violet, I really don't know how it will absorb.  And what power you need really depends on how well the polystyrene absorbs the light.

I also think you're going to have a really tough time focusing the laser to 10micron dot size.  At that, you're getting back close to the width of the active region/width of the mode coming out of the laser. Getting a diode laser to focus that small could be pretty tough, and I'm not sure what all would be involved to get it down to that small. Generally, going to gas lasers, DPSS, etc, kinds of lasers besides laser diodes, you can get more power and better beam specs than with he diodes lasers used here. Gas or DPSS is going to almost have to be commercial, not do-it-yourself.

So on the surface of it, just guessing as to the absorption of the colors of light you can easily get from standard laser diodes and the power available in those diodes, and the amount of effort it will take to get a 10micron dot size, I don't know if you're going to be able to get it in a handheld, and it may not be cheap or easy.  IR may be the best bet of the diodes available, and the optics with IR presents another set of challenges.  And power out of laser diodes is always going to be fairly low, especially relative to the beam size.  But hey, if you make it work, I want one too!

I think the best wway to test would be to just get a laser and see how much it takes to melt the polystyrene. You can get cheap red and violet lasers, focus as small as you can, and see if it melts the polystyrene at different powers.

You just want a rapid prototyper for yourself, or is it for a business or something?  Because you'd save a lot of heartache going to a commercial solution if the money is available, because you can buy these things pre-built, I believe.  My old research group did several projects with a rapid prototyper that used an electron beam and metal powders (we mostly used titanium) to make arbitrary shapes, test samples, and such.
 

lugnut

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Thank you!
That was a very helpful reply.
So, to reach the goal I will have to use a commercial laser. (well, if you guys cant make it work, I have no chance of that either :) )

But I can get a "thick" laser and experiment on the actual melting... This is a good idea, ill try to read up on that. If I can get some results, and set accurate specifications, it may help me when I will to try to get a commercial one. (then I will know it will work)

To answer your question: Yes, I both want a rapid prototyping machine for myself, and to produce them.
The current models are very expensive, meant for business customers, I believe that it is possible to make a rapid prototype machine for the home hobby user.
 
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Home rapid prototyping machines would be awesome.  

Another idea: if you can get powders that are dyed a color other than white, that would help with absorption and maybe make it more feasible/doable.  Like dyed black, or dyed green if a red laser is better than the best available violet.  And I'm really not sure about the polymer absorption of IR, but that could be worth a shot if the red or violet don't do well.

But really, I think the best thing would be to get a good red laser and a good violet laser, both are available here for pretty cheap in nice handhelds, and see if either one will melt the polymer.  Red can be easily gotten in 300mW; violet 100mW is easy as well, and probably even higher power from the right users around here.  Green is also easily available, but quite a bit more expensive for the equivalent power levels, so I don't see it being worth the extra expense.  But just see how well you can focus it, and how well it melts the polymer at the optimal focus.  Have you looked to see if any other polymers would work as well or better than the PS?  Also, if you don't want to invest in the lasers yourself, you may be able to get someone here to test out their lasers with polymer powders.

Past the laser, everything else should be pretty easily doable for you.  It's a great idea, if the laser can be made to work well enough with the polymer, it should work out great!

ETA: Also, if you're going to be working up close focusing the laser in white polymer materials, make sure you have proper vision protection.  the reflection from up close of a 300mW red or a 100mW violet will do some real damage
 




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