Focussing many diodes

Okay, I've done some searching around and this topic is surprisingly hard to find things on.

I saw the 24 diode laser at the burning man thing, and I've been wondering of compact ways to mount and focus multiple lasers onto a single point, for a really awesomely powerful laser pointer.

Now what I was thinking was instead of the traditional method of making everything into a single beam, requiring knife edging and the like, for raw burning power on a single spot, you could focus a ring of diodes, using mirrors and then two lenses (or one, I don't know) onto a point. Something like this:



Now I realize that it is kind of useless for sustained burning (because once you burn past that one spot, you now have separate individual beams, so if you want to focus on something behind the hole you've just made, it will not work), however, for raw melting power on a single spot (maybe its a gun or something, I dunno.) it should be much simpler then knife edging plus PBS cubes and optics. And it won't get me sued, apparently.

Oh god lasers bouncing off of mirrors.

Anyway, has this been discussed before? Its rather hard to find discussions about focusing multiple diodes because searching for it shows no results.

Among other ideas are having multiple aixiz modules mounted in a circle, each on a one axis hinge towards the center, and based on distance, tilt all the modules at the same time to point at one spot. Combined with the aixiz's built in focusing, you could get some intense power levels.

But then I thought of this and realized that you could just slide the last lens back and forth to get the same effect. I dunno.

I would control all of this using a range finder and a micro controller to automatically position the lasers based on the distance, or something. Or a manual focus.

I'm probably just being an idiot, lol.

Also I haven't been on in forever. How is everyone?

well the bottom drawing circle is almost exactly idea i had, but with Nd:YAG rods, and flash cavities. of course it would require some pricy optics...well, the entire thing actually, but it could be used for punching holes in steel yards away...

the second drawing would be difficult to find the correct optics, the third, you could use some kind of parabolic reflector, then reflect it back through the middle and focus it

I was thinking of using pulse lasers but I am not really sure how on earth you use them, where you get them, or anything. So... I was thinking 18 445 2w diodes all focused onto one beam would be kind of awesome.

And then I could make it all pretty and make this:



and then sci-fi laser guns here we come.

Come on aliens, just stand still for a few seconds so my laser can burn a small hole in you. No, stop moving, it won't damage you!

Won't work. The resulting beam will have large spaces between the "beamlettes." It's like knife edging, but not even trying to get the beams close.

beamlettes...ah that makes sense

what if each was beam was focused so that they all overlapped, and thats when it was focused down to a tiny spot?

either way, if the spot was small enough it would be like a, depending on the ammuont of lasers used, and rings of arrays, bad TEM rating, but with a high power for each dot

Sure, there's no reason why you couldn't focus a bunch of lasers on one spot.

Yeah, that's what I am talking about. Focusing multiple beams onto one spot, so you combine the power. Now however I'm wondering if you can use the optics to actually kinda straighten it out into one beam, like compact them really close together and then use a beam expander in reverse to really squish them together.

Is something like this possible and if so what sort of lens would that optic be?

Yeah I mean theoretically that should exist. The only thing you need to do is have a precise way of making the lasers come in at an angle like that. Either physically orient the aixis modules/diodes or have a ring mirror or mirrors arranged in that way like in my design.

I just make thought of this, I dunno. You could also do this with cylindrical optics on a flat surface to remove one dimension of complexity.

Yes, I think it is possible to bring an array, say 10" diameter down to 1cm. It's all just a matter of finding the correct focal lengths and sizes. And that's where my optics expertise end

yeah, and then once its down to 1cm, simply use standard optics to focus it, and you suddenly have a ton of diodes focused into one point. I wonder how well 20 watts of 445 will burn. ;D

Wait, if we focused all the lasers onto one point on a standard convex (or similar) lens wouldnt it put out one beam at the other end? It would be a matter of aligning the lasers closer or further apart to change the angle at which they enter the lens, and then at some point the lens would put out a single beam. That would be pretty cool.

You can focus them to a single spot just fine. This has been easily demonstrated in the c@sio projectors. But you can't get a good final beam unless the incoming beams are already very close.

Here's what'll happen:



The space between the beams doesn't disappear; it gets smaller - just like the beams themselves.

Yeah, at some point its perfect. Just takes veeery careful tweaking.. I think. I have a ton of optics from the projector I tore apart so.. might be able to try things. I just need to get a bunch of laser diodes. lol

Then would'nt mirrors be a good option? There are a few builds around here that people have done using 2 445nm diodes and using 2 mirrors to churn out one beam, all in a handheld, wouldnt it be possible to use this same setup, but several times in a row.

Oh man that's.. wow. I feel like an idiot.. lol. Now I know why its not so easy. Thank you for that.

Maybe beam expanders to make the beams bigger before they hit the shrinker.. I don't even know.. Man optics are complicated. We need black hole optics. Point all the light at it and then it all comes out at one point.

Also, yeah, thats true. I am using the mirros to pretty much put the beams on top of each other already.