Lasers vs LEDs in the deep ultra violet spectrum, and focusing?

I am currently trying to research this topic as I am looking into building a stereolithograph 3D printer. I have been searching for some time now with not a whole lot of answers. This is not my area of expertise so I could use some input. I have found lasers in the range of 256nm wavelength but it is going to cost me an arm and a leg. Even at the price range the UV lasers are only outputting at most 1W of power. I have read that UV curing resin is most reactive in the range of 265nm and that is why I have been searching for something in that ballpark. I have found some companies that manufacture LED in that wavelength but then the problem is going to be trying to focus the light down to a fine enough point. I am trying to design a 3D printer that is in the high resolution range.

So, my true question is. Does UV curing resin react best with the 265nm vs the 400nm range as I could just a blu-ray laser. If it is better at the 265nm range, could I possibly be able to focus enough light from a couple of 3W leds down to a small enough point to cure the resin where I want it to be. The other idea is taking a UV laser in the 400nm range and focusing the beam down to get me fine but quick set up time in the resin. Or possibly multiple Lasers

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ColtanA (author) 2 years ago

Well, here is a stupid question. I have been browsing around they have resin that is just photosensitive that is in the 800nm spectrum . Does anyone have experience in just using photo sensitive resin and use a IR laser which is much cheaper and much more powerful. My concern with using IR sensitive resin would be that it would set up beyond where I want it to be cured. Any inputs?

You only have the option to use a laser.
A lot of places sell small 1-5mW modules with a focus lens.
Question would be: How fine do you need it? How good are your skills with galvos?
If you want to use a router system like a conventional 3D printer you have to match the print resolution and movements to the diameter of the laser.
Is the beam too small for the minimum print width the resin won't be cured properly, same if the laser beam is too big but then you also get a lot of unwanted cured areas.
The ideal case would be a wide beam laser with it's focal point right on the layer you want to cure.

ColtanA (author)  Downunder35m2 years ago

Well, the plan was to use a threaded rod along with a gliding rails which is most likely going to be 32 thread per inch. Most stepper motors are going to have 180 steps per one revolution. So, that is going to be 5760 steps in one inch. which equals out to be about an accuracy of 20-30 microns. A spec of dust is about 25 microns if that gives you an idea of the level of accuracy I am trying to go for.

The intention of this 3D printer is to be a multifunctional device. (Laser cutting/etching, and CNC) so its going to have the conventional setup with an XYZ and possibly later on add ABC movements to the head as well.

The laser as I have found is going to need to be in the 360nm wavelength range, so does anyone have experience with using a laser to cure resin and what are most people using? Is a 365nm laser going to have a quick enough cure with only a 1-5mA output? I know I could make a simple but effect DLP 3D printer but then limits the multifunctionality of the device.

I suppose I could use a general wide beam for the laser and not try to use a lens to focus it to a finer point. Then just have edges of the object be overlapping towards the edge, but then my concern would be curing more material elsewhere that I don't want.

This is still in the very early stages of development and it has a big impact on how I need to design the base of the device. Any kind of input is appreciated.
Thanks

-max-2 years ago

I think he is referring to a different type of 3D printer, the resin filled one's where there is a container filled with resin, and a laser shined on it from underneath to cure it, or something like that. I saw one at the UVA openhouse last month.

iceng -max-2 years ago

Rodger that -max-, I realized my error an hour ago, if you had just read on.

ColtanA (author) 2 years ago
I am trying under stand what you said,
I was thinking about using a fiber optic cable to the head of the printer but it depends on the frequency of the laser. The problem lies within getting the UV light to be focused enough to go through the fiber optic cable if you use an LED. A laser wouldn't be the issue with the fiber as that could be set up directly to the fiber optic and then at the other end use a lens to focus the beam. I imagine the UV penetration into the resin is going to resemble a cone. The very center is going to have the highest concentration of power thus curing the resin much more quickly. That being said, I am thinking about using a lens to vary the coverage of the UV light to give me greater coverage in areas with less detail.

I am not sure what you are referring as a melt output or the 3D print stylus.
iceng ColtanA2 years ago

I made the mistake, your 3D is a bed of resin where you lower the platform after each planar pass and you do need a point of light.

Got a datasheet on the resin system ?

ColtanA (author)  steveastrouk2 years ago
http://www.suscomp.com/resins.htm

http://www.threebond.co.uk/Products/ThreeBondAdhesivesPottingAgents/AcrylicUVCuringResin/tabid/224/language/en-US/Default.aspx


I can't find my original product that I saw that was wanting it to be in the 265nm range. But these two are in the 360 - 365 range. Which would make things a bit cheaper and a little more doable. But the same questions apply.