Homemade CO2 laser

[DashApple]

Chris at HPC is an old friend I've had quite a few of his machines so far without any problem. He's a clever chap too, there isn't very much he cannot fix when the need arises.

Ah Cool , I met Chris once when he dropped the tube off at mine .

Was easy to deal with HPC aswell

 

[Spooky]

I'm looking to buy another YAG now, only need a baby one to do some small parts that won't run well on the bigger machines. 1,000 watt Fiber with a 1500 x 900 cutting bed. Should be fun

I'm on tube swap outs next week so will probably have some more tubes available

cheers

Dave

 

[trussmonkey25]

The negitive always goes on the partially reflective side. and the positive goes on tge fully reflective end. dont forget to have an earth ground near the postive incase the tube breaks down...about two inches away from it..50 mm

 

[HDF49]

Bit of an update, progress has seriously slowed now I'm back at school though! I've had the opportunity to sneak into the workshop every now and again and I've remade the electrodes and gas ports, and I'm ready to glue them up soon. As you can see the electrodes are going to be outside of the glass tube, so the beam shouldn't be occluded by the electrodes, and there'll be a longer discharge length, so more power, however the whole discharge won't be cooled. It should also prevent cracking of the glass due to thermal expansion. They are made from 15mm copper plumbing pipe, with brass hose barbs I turned and the aluminium mirror mounts are the same as before, just drilled out to accept the wider pipe.

 

[The Lightning Stalker]

Looks very nice! I can't wait to see some burning. :gun:

Do you still need wire? I have a crap ton of 34AWG. Can send you some

Also I don't exactly understand the coolant flow. Is there another pipe within the pipe we can't see?

 

[HDF49]

Thanks! Nor can I, it's just going to be a longer wait than I hoped, possibly around christmas time when my university application is all done, but I'm finding a bit of time to get in the shed after school and at weekends.

Spooky very kindly gave me a 80 watt laser and its power supply so I'm sorted when it comes to the power supply! I would like to have another go at making my own power supply at some point, but I have a big spool of wire around 34awg, and I'm looking for something a bit thicker for the transformer, thanks though!

In this photo of the original laser the main tube you see is a 30mm plastic cooling jacket, with an 11mm glass tube within it, which has the electrodes and mirror mounts inserted at either end.

However I've now rebuilt the electrodes so they are mounted around the outside of the glass, a lot like this one:Jarrod's Laser World: First CO2 Laser, But the glass tube I bought only comes in 0.5m lengths, so the cooling jacket will be cut down to keep it away from the electrodes so they don't short across the water. So what I'll have is a 35cm or so cooled section in the middle of the discharge, a bit of a gap, and then the rebuilt copper electrodes.

 

[The Lightning Stalker]

Oh I see it now. I was confusing the water ports with the gas ports.

 

[HDF49]

Progress really slowed down with this project after getting back to school, I started my last year of sixth form and got swept away with applying for a physics degree. On the plus side I wrote about this project in my personal statement, which clearly grabbed attention because I got invited to Oxford for interview, and was asked "what's this about a CO2 laser?" before I'd even sat down! I got an offer from them in the post a few days ago so I'm in a very good mood, and with a bit more spare time now!
I've completed those new electrodes and I'm working on an enclosure to keep the whole thing away from getting knocked, and I also salvaged the high reflector from the tube donated by spooky, which I'll experiment with if I'm having no luck with my plane HR. Pics should be coming soon hopefully.

 

[Spooky]

Good news and a great choice of Uni, it's been some years since I attended there but I doubt it has changed much

cheers

Dave

 

[HDF49]

I can't imagine it has! What college and what did you read if you don't mind me asking?

 

[bloompyle]

Oh hey! Cool seeing someone else doing one as well

I haven't read through this all, yet, though I also have one in the works. I have the water cooling jacket built, and plan to use borosilicate for the tube as well.

I have a couple diagrams around here of my plans. Currently trying to conquer the issue of electrode sputtering from the positive ions striking the cathode. Also working on a way to have a gas in/vac out (flowing gas unit) without having current go down the gas/vac lines. In theory, if you use tubing thin enough, it won't be an issue.

Anyway, I don't want the thread jack.

I will be watching this thread, and I am interested in seeing where our designs are similar and not.

 

[HDF49]

Good to see it's not just me, regarding the cathode sputtering I hear that aluminium has low sputter, because its outer layer oxidises quickly. And with the vacuum lines it's a matter of long thin tubing, and making sure all the controls are well insulated! I'm worried the pin valve I have bought hasn't got fine enough threads, so I hope I can get the required control of the gas flow

 

[bloompyle]

Good to see it's not just me, regarding the cathode sputtering I hear that aluminium has low sputter, because its outer layer oxidises quickly. And with the vacuum lines it's a matter of long thin tubing, and making sure all the controls are well insulated! I'm worried the pin valve I have bought hasn't got fine enough threads, so I hope I can get the required control of the gas flow

I was considering making a sidekick tube with similar ID PVC for the electrode, and sealing the whole thing with JB weld or something.

I'm not worried about discharge down the vac lines, that's the same advice I was given.

What quality gas are you using? To be completely honest with you, I'm using my own breath and party balloon He for this thing. Going as cheap as I can with the prototype.

For the advanced design once I get my feet wet with vac systems, gas fill, mirror alignment, etc. I plan to do something a bit more .. professional.

I'm going to blow up a balloon with a bit of He, then breathe into it. This will be attached to tubing that will go to a gas release valve beyond the balloon that slowly deflates the balloon into the tube. So it also won't have long run times, again, not worried about that.

Very simple, but if I can get resonation, then I can work on more permanent ideas, currently I just want to get photons to exit.

As long as it runs, that's what I want from this. It's also going to have a permanent beam block a foot or so beyond the OC since I live in an all wooden dorm. Wood walls + 25W = arsonist.

Thoughts?

 

[HDF49]

I don't quite understand what you mean about the 'sidekick tube'?

After my initial trouble with the tube cracking I'm working on very solid mounting, so I have milled some little acrylic V blocks, and I'm going to buy a length of aluminium channel which the v blocks are going to be bolted to, and I'm going to epoxy the whole thing in to the v blocks, which should hopefully insulate the HV from the aluminium channel and provide security to divert the forces on the vacuum and water pipes away from the glass tube.

That is exactly what I'm planning on doing for the supply, copying Jarrod Kinsey as much as I can because that man has done it already and with a fraction of the tools I have access to!

I will be over the moon with any output to be honest, this whole thing is being done as a school project and my own little foray into laser physics, so for the write up I need proof that my plan has worked, and for me I would love to be able to burn things from a distance with my homemade laser!

What will you be aligning your laser with? I picked up a 10mw hughes HeNe for £10 on ebay for the job!

 

[bloompyle]

I don't quite understand what you mean about the 'sidekick tube'?

After my initial trouble with the tube cracking I'm working on very solid mounting, so I have milled some little acrylic V blocks, and I'm going to buy a length of aluminium channel which the v blocks are going to be bolted to, and I'm going to epoxy the whole thing in to the v blocks, which should hopefully insulate the HV from the aluminium channel and provide security to divert the forces on the vacuum and water pipes away from the glass tube.

That is exactly what I'm planning on doing for the supply, copying Jarrod Kinsey as much as I can because that man has done it already and with a fraction of the tools I have access to!

I will be over the moon with any output to be honest, this whole thing is being done as a school project and my own little foray into laser physics, so for the write up I need proof that my plan has worked, and for me I would love to be able to burn things from a distance with my homemade laser!

What will you be aligning your laser with? I picked up a 10mw hughes HeNe for £10 on ebay for the job!

For the side tube, think of a cop's nightstick. Like:
__________| |____
________________

That little extra bit protruding is the "side kick" tube. Basically, it's where the cathode will be to prevent sputtering of said cathode affecting the mirror.

I'm modeling a lot of this after Kinsey, as I think he did the most documenting of his. Though I also have a couple books with diagrams of various laser designs.

I will be using one of my HeNes, I've got plenty to choose from here.




As far as using He, yes, it's not required, but it will certainly make things easier to lase. In a DIY environment, anything I can do to help this along, I will do. Though it's not worth the pretty penny for 99.999% pure like I would need for an HVL

 

[HDF49]

Ahh I see, yes I'm sure that would work very well to prevent sputter, how will you fix the sidekick to the laser tube? Can you blow glass?

I've got a cylinder of He for party balloons, and I'll use CO2 from baking soda and vinegar or a welding tank and nitrogen from the air or a welding tank. From what I've heard the high efficiency CO2 should allow for all this....