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20 Watt Laser Gun Project

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Apr 11, 2019
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Hey everyone. Just wanted to share my project I have started. I'll be adding new images here as I go. This project is a $200 budget laser gun(SMG stlye). The components are 3 fan cooled 7 watt modules knife edged combined. This is the first time I've done any sort of beam combining. All of gun pieces are 3d printed, this includes the alignment plate.

It was a little tedious aligning the beams but they are pretty good. The gun is now mostly done, but I am struggling to get decent beam expansion for long range.

I'll post more shots as this develops.

Here is the latest video showing the mostly completed gun.



Beam shot.

20190521_204858.jpg

Alignment pad.

laseralign.jpg
 
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RedCowboy

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Are those round mirrors ?
You will do better with " Front surface or First surface " square edge mirrors, you can get them for cheap from ebay.

---edit---
Actually if all you are using is a single primary collimating lens then the divergence is so bad that it really won't matter, you are pretty much just going to converge at a short distance anyway.

Are you planning to use a beam expander of some sort on all 3 beams when they are running together ?

These are useful, you can adjust X and Y by the base mounting and rotating the upper > https://www.ebay.com/itm/Adjustable-Optics-Mount-for-Laser-Optics-Mirror-Mount-445nm-520nm-635nm/142408738168?hash=item212838e578:g:Ce0AAOSw3YJZOWhR

Here's a better way if using 3 x 7w multi mode lasers IIHO ........If using 2 x 7w MM lasers then a PBS cube can be used.

C-lens pairs to correct that aggressive fast axis then knife edge all 3 beams on the same plane and employ the longest telescopic reduction you can fit into your device for a " Point and use - No focus needed " device.




64632
 
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  • Wow
Reactions: GSS
Joined
Apr 11, 2019
Messages
58
Points
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Are those round mirrors ?
You will do better with " Front surface or First surface " square edge mirrors, you can get them for cheap from ebay.

---edit---
Actually if all you are using is a single primary collimating lens then the divergence is so bad that it really won't matter, you are pretty much just going to converge at a short distance anyway.

Are you planning to use a beam expander of some sort on all 3 beams when they are running together ?

These are useful, you can adjust X and Y by the base mounting and rotating the upper > https://www.ebay.com/itm/Adjustable-Optics-Mount-for-Laser-Optics-Mirror-Mount-445nm-520nm-635nm/142408738168?hash=item212838e578:g:Ce0AAOSw3YJZOWhR

Here's a better way if using 3 x 7w multi mode lasers IIHO ........If using 2 x 7w MM lasers then a PBS cube can be used.

C-lens pairs to correct that aggressive fast axis then knife edge all 3 beams on the same plane and employ the longest telescopic reduction you can fit into your device for a " Point and use - No focus needed " device.




View attachment 64632
The mirrors are what I have available. I would like to get proper mirrors at some point.

Yes, a beam expander is planned! Thanks for the diagram. Your setup looks interesting, but I'm not too sure about space efficiency for the internals of the gun. Wouldn't it be basically the same thing if i put a beam expander on the end of my plate?
 
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RedCowboy

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Not even close because the 1st giant hurdle to making a strong tight beam from these multi mode blues is the uneven divergence with the fast axis being very aggressive, but if you just want to knife edge the 3 beams and use a home made beam expander it is worth doing, it just wont make as tight of a beam.


BTW Have you measured the output of your modules ?

Have you measured the length of your focused spot which will look like a small bar/line ? You have to focus a laser at a distance of say 5 meters ( 15 feet ) and see how long your bar/spot is, make sure to wear your laser safety glasses that attenuate the 450nm wavelength in this case or whatever wavelength you are working with so that you can see the true output and not just the bright splash.

At 5 meters the real 7W diodes ( 0A, 08, 44 ) with a G2 lens will make a bar/line that's 1.75 - 2.0 inches long or 44-50mm long ( at 5 meters ) and with a 3 element your line will be close to an inch long or about 25mm long ( at 5 meters )
NOTE: You can swap out your 3 element for a G8 lens and gain 20% or so just that easy without suffering any change in your spot/bar length.

You may have 08 diodes with Chinese G2 lenses which could actually hit 7W but would be closer to 5w each with a 3 element, however if you changed your 3E for a G8 you could have the same power as the G2 but keep the 3E divergence.

Anyway if simply knife edging and using a BE you may want to change your collimating lens which is a quick easy 1st step improvement.
 
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Here's the gun so far! Works pretty well, been struggling to get functioning beam expansion for long range though. But the alignment is pretty good on the 3 lasers.

 

Alaskan

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Wow, big knife edges, fun project.

 
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bertha

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great experience,very interesting
 
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lasersbee

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Not crazy abouyt
Thanks guys. Here's a shot of the beam.

View attachment 64908
Not too crazy about your beam stop.o_O

If that is near 20Watts I wouldn't be pointing it
onto carpeted stairs.
Get yourself a wood burning stove liner brick
and paint it flat black or even a larger aluminum
black anodized 90 deg angle plate.

Jerry
 
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Apr 11, 2019
Messages
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Not crazy abouyt

Not too crazy about your beam stop.o_O

If that is near 20Watts I wouldn't be pointing it
onto carpeted stairs.
Get yourself a wood burning stove liner brick
and paint it flat black or even a larger aluminum
black anodized 90 deg angle plate.

Jerry

The divergence on the beam is very poor. So it has a pretty low range. After about 5-6 feet distance it struggles to burn materials that are not black or dark colored. I would have to hold the gun very steady in one spot for at least 10-20 seconds on a light color carpet at that range.

On the other hand, if I had a beam expander I would feel nervous about pointing it at the carpet or walls.
 




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