CO2 laser questions

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CO2 laser questions

Postby laser123 » Wed Jan 19, 2011 1:04 am

I know almost nothing about lasers but would like to make a 60W CO2 laser. Can someone please help me I would like to know the components and where to get them. Also I would like to know how to eventually turn it into a CNC laser.
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Re: CO2 laser questions

Postby r691175002 » Wed Jan 19, 2011 1:19 am

laser123 wrote:I know almost nothing about lasers but would like to make a 60W CO2 laser. Can someone please help me I would like to know the components and where to get them. Also I would like to know how to eventually turn it into a CNC laser.


It is simply impossible to create a sealed CO2 laser without tens of thousands of dollars in vacuum equipment, glassworking equipment and ovens.

Flowing gas CO2 lasers aren't extremely practical since you need to constantly provide a mix of gasses in lasable quantities which is expensive and inconvenient. You also have to keep these gassses under a vacuum which is both expensive, dangerous and difficult.

Manufacturing even the simplest CO2 laser would cost you at least twice as much as buying a tube from China. Something viable for production would cost at least and order of magnitude to make yourself than it would cost to buy.

If you are interested in lasers the bible is here: http://www.repairfaq.org/sam/lasersam.htm . I fear you have vastly underestimated the difficulty and safety hazards of building a laser cutter.
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Re: CO2 laser questions

Postby bdring » Wed Jan 19, 2011 1:56 pm

Making your own laser tube is not practical, but probably a lot of fun. I plan to build my own tube some day. I have heard some people say the gas for a 50W tube can cost as little as $1 per hour to operate. I saw one guy even ran a low power flowing C02 laser on exhaled air.

Here is an interesting web site: http://www.hobbycnc.hu/CNC/Laser/Laser.htm
Here is a PDF of plans: http://www.hobbycnc.hu/CNC/Laser/55_Wat ... r_Tube.pdf

I made my own design based on those plans with to easier to procure parts. The end plates are aluminum and use 3/16"-100 Thorlabs adjustment screws. As soon as I get some time and find someone to make my end plates, I will start the build.

Untitled Project 17.jpg
My Tube Design
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"If you didn't build it, you will never own it."
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Re: CO2 laser questions

Postby r691175002 » Wed Jan 19, 2011 8:38 pm

Would you mind posting some drawings?

Coincidentally, I actually have everything required to build a laser tube with exception of a vacuum pump and optics. My serious hobby is glasswork and I've got a small machine shop and a tank of co2 that could be refilled.

Optics look to be in the 150$ range off ebay but I'll have to look into a vacuum pump. Id like to stay away from fridge/ac stuff but getting the recommended 140lpm from a rotary vane pump is looking expensive.
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Re: CO2 laser questions

Postby bdring » Thu Jan 20, 2011 3:03 am

Right now the design is only a 3D model. The only drawing I made so far was the end plate with the focusing screws. I can send you a STEP file of the assembly model if you like. I do not want to post the files publicly until it is a tested design.
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Re: CO2 laser questions

Postby trwalters001 » Thu Jan 20, 2011 3:18 am

Hi laser123,

Take a look at this:

http://www.buildlog.net/forum/viewtopic.php?f=16&t=320

As you can see, I've built the laser and laser cutter in the past.

However, I'm using a factory-made, sealed-tube laser now. If you want to make your own laser, I'd suggest using the plans that Bart talked about in a previous post. It took about a month to build the slow-flow laser, and about 2 months to optimize everything and get it running correctly. It takes quite a bit of floor space, quite a bit of equipment, and LOTS of "messing" with it t keep it running. You won't be able to control the power so that you can engrave unless you build/buy a power supply. Cutting is pretty much brute-force. Run wide open and see what you can cut.

If you want a cutter/engraver, your best bet is going to be to build Bart's design (including buying the laser tube and supply.)

If you want a slow-flow laser, I'll sell you either one (or both) of mine...

My $.02

Tim
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Re: CO2 laser questions

Postby macona » Tue Jan 25, 2011 3:24 am

r691175002 wrote:Would you mind posting some drawings?

Coincidentally, I actually have everything required to build a laser tube with exception of a vacuum pump and optics. My serious hobby is glasswork and I've got a small machine shop and a tank of co2 that could be refilled.

Optics look to be in the 150$ range off ebay but I'll have to look into a vacuum pump. Id like to stay away from fridge/ac stuff but getting the recommended 140lpm from a rotary vane pump is looking expensive.


Its not just CO2 in the laser, it is a mix if CO2, Nitrogen and Helium. You can get a bottle of laser mix from places like airgas or other industrial gas suppliers. It will probably set you back about the cost of a chinese laser tube. You can also mix the gas from three bottle. In the old scientific american article they used purified atmosphere, dry ice, and helium, IIRC.

You do not need a 140lpm pump, it would be nice but not necessary. You can get away with something as small as a little alcatel 2002 if you have good gas handling equipment. I use one of these on my mass spectrometer. Direct drive pumps are noisier and run faster than the old belt driven pumps.

You are also going to need either a thermocouple gauge or a capacitance manometer to measure pressure. A cap mano with a 100 torr range would be good.
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Re: CO2 laser questions

Postby r691175002 » Tue Jan 25, 2011 11:23 pm

Is it necessary to get a prefilled bottle or can you get an existing cylinder filled with laser mix? I've got a 5lb tank and I'd assume that if it can hold co2 safely, nitrogen and helium shouldn't be a problem.

I'll look into this further after I've finished my laser cutter. To be honest, I've always wanted one of those multi-line argon lasers and the process looks similar. I can only imagine how expensive a bottle of spectroscopic grade argon is though.
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Re: CO2 laser questions

Postby macona » Wed Jan 26, 2011 3:08 am

No, bottles meant for CO2 will only hold CO2. CO2 is in its liquid form when stored in a cylinder and the max pressure a CO2 cylinder will see is about 750 PSI. Nitrogen and Helium are usually around 2700 to 3000 PSI. So you will need a new bottle and a regulator with a CGA540 tank fitting. Depending on your local gas supplier you may be able to lease a tank but most places in the US usually sell the tanks 150 cuft and under.

Oh boy, argon lasers are on a whole different level than CO2. CO2 is very simple and very high gain so errors in initial alingment are not that critical. Also CO2 lasers can be made from common pyrex and even soft glass since they typically have a large bore. Tube voltages are high and currents are low, 10 to 30ma on average.

Argon (and Krypton) lasers on the other hand are much more complex. They require a filament for electron emission since the tubes run at a much lower voltage, anywhere from 100v at 8 amps for something like an old spectra physics to a couple hundred volts at 50 or more amps on the larger frame units. The bores are very narrow because you need energy density for the argon to lase and because of this cooling becomes an issue. The air cooled laser tubes use a bore made of beryllium oxide ceramic which is highly hazardous. End bells are attached with a special silver braze. Tubulated glass holds brewster windows at a specific angle at the ends of the tube. Larger frame water cooled argon lasers use a magnetic solenoid wrapped around the tube to constrict the plasma away from the walls of the tube.

Power supplies are complex. Not only do you need a transformer or solid state equivalent to drive the filament you need a high power constant current power supply. Even a small frame air cooled argon outputting 10mw of green will pull 15 amps at 120v. The mid frame lasers like the Omnichrome 543 or 643 pull 20 amps at 240v. Thats almost 5kw. They heat the room real well!

Scientific American has an article in their amateur scientist column on building a pulsed argon laser. It charged up a capacitor and then discharged it through the laser tube and you would get a very short pulse of blue laser light.

There is no sense in building one. The price has dropped considerably now with the advent of DPSS lasers. The round uniphase units can be found pretty cheap. You need an appropriate cooling fan! This is extremely critical on one of these lasers.
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Re: CO2 laser questions

Postby trwalters001 » Wed Jan 26, 2011 1:53 pm

I'm going to assume that you want an argon laser because of the colored beams. Your best bet would be to follow macona's suggestion and get you some solid-state lasers. They're very cheap and you can get red, blue and green to make whatever color you want. A 10mw argon will set you back at least several hundred dollars as well as being a PITA to run. Combining 100mw of solid-state of each color (RBG) would cost less than the argon. Go to http://www.photonlexicon.com and start reading.

Tim
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