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Making a portable CO2 laser?

Sta

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Hello folks!

I've recently been considering constructing a portable CO2 laser.
I realized that when I built my 7W NUBM44 lightsaber, I dug myself into a bit of a hole - in order to make my next 'viral' video, I have to top that!

I essentially have two options:
(1) a diode array, which will be expensive and have a very spread-out beam,
(2) a portable CO2 laser, which will have short runtime but much more concentrated power.

I would much prefer a portable CO2 - it has not been done many times before, and I think it would be unique and impressive.
Anything in the range of 30-40W would be fine, and the duty cycle does not have to exceed 30 seconds.

Unfortunately, I don't quite know where to start. I haven't dealt with CO2 lasers before.

What kind of battery would be necessary to accomplish this? What kind of power supply? And how should the wiring be done?
 



diachi

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How portable do you want it t be? A 40W CO2 tube isn't all that small, requires water cooling and a HV power supply.


You could go down to 15W and have something more manageable:


But if you're going that low you'd be better to look for one of those small RF excited CO2 lasers, the RF amp on those usually runs directly off of DC, they are air cooled, lightweight and small. Not to mention usually a lot less fragile too.


One of the guys over on PL has one of those in a nice portable setup I believe, or at least had, that was years ago. I'll need to root around for the pictures.

Edit: I was mistaken - the one that Robin on PL has/had that he showed off at UKLEM was a regular HVDC powered glass CO2 - 10W apparently:



That power supply looks like a flyback and perhaps a ZVS to me...
 
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Sta

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Thanks diachi. A 700mm 40W tube is fine, actually - makes it look more like a laser rifle, which is ideal.
And I think a small to medium water tank with a pump would probably be sufficient for short runs. Notice that in the first video you posted there is no water cooling, yet he states it works fine if duty cycle is limited to 20 seconds.
 

diachi

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Thanks diachi. A 700mm 40W tube is fine, actually - makes it look more like a laser rifle, which is ideal.
And I think a small to medium water tank with a pump would probably be sufficient for short runs. Notice that in the first video you posted there is no water cooling, yet he states it works fine if duty cycle is limited to 20 seconds.

Oh yeah, it'll work without water cooling, just not for long at all, go too over the top and you damage the tube irreparably.

If you're fine with the size then 40W is the way to go. You could probably put together a power supply if you know what you're doing - although something off the shelf may work fine, there are some fairly small options out there:

40W Power Supply CO2 Laser ENGRAVER Cuttier Machine 110V 220V Switch Green Sale | eBay

That wants mains voltage, you'd need to use an inverter with that one if you're going for battery power. Should be able to find something that runs off of DC if you can't build it. HV power supplies aren't my area - I'm not sure if a big flyback and a ZVS could power a tube that large. There's several people on here that are familiar with high voltage power supplies and such - they'll be able to tell you. :)

Power draw on a tube that size is a little over 200W. By the time you take into account power supply inefficiencies and such you'd be wanting to budget for about 300-350W DC input - that should give you some overhead. Knowing that value you can decide on batteries, taking into account size, cost and weight.
 

RedCowboy

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I like how this guy used pvc, I had the same sort of idea, the ZVS driver is a neat trick too, I started buying parts but could not get a tube from the same Chinese supplier and like so many things it got put on hold.


This is cool, I think 5 shots a second is slow but it's a nice looking build.

 
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Benm

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If you only want to run 30 second bursts you can probably do without the water cooling. There should definitely be water in the cooler, but no need to circulate and cool it. You can measure the water volume in there and calculate the temperature rise with time for a give power level easily.

I think the main hurdle in this project would be the power supply. It's perfrectly possible to derive the required power from a lithium cell pack, but also very dangerous - the outputs to the laser tube are absolutely lethal when touching both.

An RF-pumped laser could be ideal for this if you can find one. You should get a completely contained unit unless you are very well aware of the risks of high power RF though. Making mistakes with that is about as dangerous as sticking your head in a running microwave oven with the door interlock bypassed.
 

Crazlaser

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If you only want to run 30 second bursts you can probably do without the water cooling. There should definitely be water in the cooler, but no need to circulate and cool it. You can measure the water volume in there and calculate the temperature rise with time for a give power level easily.

I think the main hurdle in this project would be the power supply. It's perfrectly possible to derive the required power from a lithium cell pack, but also very dangerous - the outputs to the laser tube are absolutely lethal when touching both.

An RF-pumped laser could be ideal for this if you can find one. You should get a completely contained unit unless you are very well aware of the risks of high power RF though. Making mistakes with that is about as dangerous as sticking your head in a running microwave oven with the door interluock bypassed.
I can't claim to know anything about these lasers, but when I built my tesla coil, I started with a fly back transformer and I also messed with a few lamp ballasts. You could also use a small step up transformer to raise 22-24v from multiple 3s lipos wired in parallel and then use groups of them wired in series, to 110v. Use a few mosfets and rewire a fly back transformer for higher current, there are plenty of YouTube tutorials. You could probably manage 175 watts if you rewired. But if that's not enough power then I can't help. :)

And on a note of safety, as mentioned before high wattage radio frequencies are crazy dangerous. When testing and working with it keep one hand behind your back whenever there is power connected and make sure someone knows what you're doing.
 
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diachi

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And on a note of safety, as mentioned before high wattage radio frequencies are crazy dangerous. When testing and working with it keep one hand behind your back whenever there is power connected and make sure someone knows what you're doing.

That goes for HV in general - not just high frequency stuff. Interesting fact: RF stuff generally won't hurt because your nerves don't have time to depolarize and thus send a pain signal to your brain. Even if RF stuff doesn't kill you, it'll give you nasty burns.
 

Crazlaser

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That goes for HV in general - not just high frequency stuff. Interesting fact: RF stuff generally won't hurt because your nerves don't have time to depolarize and thus send a pain signal to your brain. Even if RF stuff doesn't kill you, it'll give you nasty burns.
Yes, also I noticed that I could touch the streamers from the coil at about 3 inches away without feeling pain, if I moved closer of further there was a sharp burning feeling. I still don't completely understand what was going on.
 

Sta

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Thanks everyone.
You folks have convinced me that until I have some more experience, I should stick to a lab-based CO2 laser. Once I've got enough time with that, it should not be too hard to convert it into a handheld unit.

On that note - how difficult it is to assemble a working CO2 laser from a tube and PSU purchased online? Is a great deal of soldering necessary?
 

diachi

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Thanks everyone.
You folks have convinced me that until I have some more experience, I should stick to a lab-based CO2 laser. Once I've got enough time with that, it should not be too hard to convert it into a handheld unit.

On that note - how difficult it is to assemble a working CO2 laser from a tube and PSU purchased online? Is a great deal of soldering necessary?

Pretty much just connect the PSU to the tube and plug the PSU in. Not sure what the connections are on the tube - i.e. if they come with leads that need soldered or if they already have wires attached to the leads with connectors on the ends.

Of course, you need to hook up water cooling, but that's fairly simple. :)
 

DashApple

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Thanks everyone.
You folks have convinced me that until I have some more experience, I should stick to a lab-based CO2 laser. Once I've got enough time with that, it should not be too hard to convert it into a handheld unit.

On that note - how difficult it is to assemble a working CO2 laser from a tube and PSU purchased online? Is a great deal of soldering necessary?
I was told by a engraving company I got my 60W co2 from not to soldier to the laser tubes pins , just wrap the striped wire round the pin and tape over it .


They are very easy to setup very little soldering is needed . The end the beam exits from is the cathode ( negative / ground ) the other end with the HR mirror is the anode ( HV Positive )
 
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Benm

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High power RF is dangerous in a different way from high voltages in general: You don't need to make contact at all to hurt yourself. For these mircowave frequencies waveguides are commonly used, and if you just leave one open holding a body part in front of that could do serious damage (the device will probably be damaged to from sucn an unterminated connection).

At low levels it just feels warm in and odd way. Luckily i've never been exposed to amounts that caused harm, but the idea of tissue cooking like raw meat in a microwave is not far off, and you don't feel that much heat when most is induced below the skin.

It's VERY dangerous to your eyes though, not so much to the retina as it doesnt focus or anything, but to the cornea and such which have no blood flow to cool them.

I was told by a engraving company I got my 60W co2 from not to soldier to the laser tubes pins , just wrap the striped wire round the pin and tape over it .
This is very common, the material the pins through the glass are made of are not of a solderable (at least with lead/tin) metal. You can wrap the wire or fit some sort of connection that friction/pressure fits (like the plug prongs inside a wall socket work). Contact resistance is not much of an issue at these high voltage, low current connections in any case.
 

AaronT

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I was certified on "electronic warfare" equipment during my time in the .mil.

That high power RF is no joke, some military hardware is a hazard from under 5ft away even fully intact. This is an issue when your supposed to have someone on a gun on top of the vehicle and the RF device has to be mounted on top someplace as well...
 

Cyparagon

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the outputs to the laser tube are absolutely lethal when touching both.
Not unless you have a heart condition. They only need 20-something mA, and the flyback would be current-limited to this value. 20mA will hurt a lot, but it's not lethal.

An RF-pumped laser could be ideal for this if you can find one.
RF pumping is way less efficient than electrical pumping. Something like 5% for RF and 20% for electrical. Not ideal for battery power.

Making mistakes with that is about as dangerous as sticking your head in a running microwave oven with the door interlock bypassed.
I looked it up, and the RF is 45MHz. The biological absorption profile and penetration depth is different at this frequency. It is also at less than half the power of a microwave magnetron. The energy is not directional like a magnetron is. The physiological dangers are therefore categorically quite a bit less.
 
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Hemlock_Mike

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Portable CO2 can be done if you can find the
parts. RF excited at 27.125 Mhz at 380 Watts
can give 12 Watts of CO2.



HM
 







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