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CO2 laser rifle optics... beam diammeter HELP!!!!

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retsam resal

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Hello everyone, I am pretty new to the forum (not to lasers). I have a question about optics for my co2 laser rifle I've recently built. I'm trying to pinch the beam down into a thin parallel beam with relatively low divergence. My thought was to use an aggressive beam expander to fan out the beam, then using a convex lens, rapidly pinch it down. Before the focal point, I'd introduce a negative diverging lens (concave), to sustain a parallel beam that would therefore reduce the diameter of my beam. Is my logic correct on this one? Or am I missing something? Id like it to have some penetration power/cutting potential at great distances without having to build a complex range finder apparatus with actuators and programming to adjust the optics to produce the minimum beam spot size on target at varying distances. Any help would be MUCH appreciated!!! Thanks so much, Danny. :gun::gun:


Check out a few pics for ligitimacy....
 

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Eudaimonium

Eudaimonium

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Yeah you're missing out a couple of things.

First, you want to use that so you don't have to use complex range finder apparatus and actuators. Why do you thing everybody uses them, because it's cool? :p If what you're saying is possible, everybody would do that instead.

Second, expanding then reducing the beam gives you ideally exactly the same beam as only reducing it in the first place. There's no cheating around the laws of physics and optics.

Smaller the diameter of the beam, greater the divergence.

If you want to change that, call Chuck Norris. No guarantee that he will not kill you for it. Just sayin' :p
 
RA_pierce

RA_pierce

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First, you need to start with some expensive ZnSe optics. A CO2 laser beam will destroy "normal glass."
Second, divergence and beam diameter are inversely related so reducing beam diameter will always increase your divergence.
In my opinion, it is best to find a compromise and make it a fixed focus laser... that is, find the largest beam diameter that still has enough power density for blowing stuff up while maintaining a low enough divergence that it can be used over a reasonable distance.
 
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LORDJET

LORDJET

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Cool project you have there! I like how you incorporated all the components in that rifle like host. The optics are gonna be a toughie. Almost sounds like you need to " scale up " something like an Axiz 3 element lens, or maybe a single element lens, like a 405 G1. But in, Znse or germainium? ( spelling? ) I guess you could try to find a suitable chunk of rock salt, and cut, grind, and polish it to the correct lens shape you need. It would be cheap, but certainly not easy! Another problem with this material if I remember correctly is that it tends to absorb moisture from the air. But I really like what you've done so far! :beer:
 
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steve001

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retsam resal said:
Anybody have any suggestions on where to find cheap optics? Something interesting I also heard was the use of salt for co2 laser lenses. Anyone heard of this?
Click to expand...

I don't know much, but I know this salt windows aren't a viable option because they frost over quickly. All lenses for co2 laser will be expensive some types more than others. You can certainly google this information.
 
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retsam resal

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Iv'e looked online for some info on salt lenses or how to's but couldn't find a whole lot. Miniaturizing the power supply and inverter was a chore times 2. (had to build an inverter from scratch bc there wasn't one I could find that was small enough... Also there seems to be a set of potentiometers on the power supply, Im a bit apprehensive about playing with them but its oooohhhhh so tempting. Don't really care if I fry the tube. Couldn't find anything online about that either...
 
LORDJET

LORDJET

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+1 for you! Thanks for sharing that video, very cool. Have you tried checking with mi-lasers.com? Sometimes they sell used co2 optics-focus lenses there, usually at a good discount. It may be hard to find the optics your looking for though. :cryyy:
 
jcranmer

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That thing looks great. You have a very nice "ray gun" there! :beer:
 
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SOG

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OH, poor router! what version is that? Actually linksys do have a few nice old version ones with more RAM... but I guess they are getting old.

I am quite new to making lasers, so can't help you with the lens an focus issues...

About Range finder, the one you mention is rifle scope base or "light-delay-measuring" base ? Actually I think making light-delay-mesuring base rage finder isn't that hard? they uses laser to show at an object, and then calculate when the light bounce back to tell the distant.

I have also seen another easy way to measure distant, it's putting two laser pointer at parallel, turn it on and then from the two dots's distants, you can tell the distance.
 
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retsam resal

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Arayan said:
agreed, it seems to me not more than 20W...
BTW very nice rifle :beer:
Click to expand...

Thanks guys :) But coletech makes some nice ultra short high powered co2 laser tubes. it's a 40W @ 700mm = 27.55 inches long. Its over driven a fair amount which I estimate to be outputting around 50W. They actually have an 80W co2 laser tube thats only 1100mm long! or 43 inches! But the diameter of the tube is larger on all their shorter tubes. I believe they call them their long life tubes, good for 8000hr+

My next units I plan on getting the size down substantially. Eventually I want to build a replica AKIRA laser rifle with that shorty 80W tube and some genuine adaptable optics for maximum devastation :) :)
 
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retsam resal

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SOG said:
OH, poor router! what version is that? Actually linksys do have a few nice old version ones with more RAM... but I guess they are getting old.

I am quite new to making lasers, so can't help you with the lens an focus issues...

About Range finder, the one you mention is rifle scope base or "light-delay-measuring" base ? Actually I think making light-delay-mesuring base rage finder isn't that hard? they uses laser to show at an object, and then calculate when the light bounce back to tell the distant.

I have also seen another easy way to measure distant, it's putting two laser pointer at parallel, turn it on and then from the two dots's distants, you can tell the distance.
Click to expand...

I have no idea bout the router, my buddy brought it over and asked if we use it for our surface mount class. I had other plans :eg: Yeah there are a few ways to do it, I know there are surplus range finders from m1 abhrams tanks that are surely quite accurate (powerful lasers in their own right) but I am not sure how I would implement it into the system. The wavelengths are so similar.
 
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