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10-27-2014, 07:36 AM #1
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TSLexi
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Building a pulsed CO2 laser

Hi guys!

I'm interested in building a pulsed CO2 laser (I recently came into acquiring a sealed laser tube and three 3 kF 2.7 V ultracapacitors). I'm trying to recreate this guy's neat invention: You?ll shoot your eye out?with a 1MW laser pulse pistol, although in a slightly larger size with a CO2

The specs I am trying to achieve are:

1. Energy per pulse: 25 J
2. Pulse width: 100 ns
3 Pulse rate: 200 Hz
4. Spot size: 1.5 mm^2

From some calculations, I have determined that the laser's average power would be 5 kW, and the peak power would be 250 MW. It would have an irradiance of 16.7 GW/cm^2, and a fluence of 1.67 kJ/cm^2.

I have also determined that the total energy required for each firing cycle of the laser would be 5 kJ, and since each of my capacitors store 10.9 kJ (.5*3000*2.7^2; a total of 32.8 kJ), I have enough energy to operate at least the laser itself, assuming 20% efficiency in converting electrical to optical power.

I'm just trying to figure out cooling requirements. For compactness, I'd like to use a Peltier cooler to reduce the water flow requirements.

Thanks, and call me stupid if you think that's appropriate

Lexi

Last edited by TSLexi; 10-27-2014 at 08:16 AM.

10-27-2014, 07:58 AM #2
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Cyparagon
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Re: Building a pulsed CO2 laser

Quote:
 Originally Posted by TSLexi I'm trying to recreate this guy's neat invention: You?ll shoot your eye out?with a 1MW laser pulse pistol
It is NOT invention, it is a device from a tank's range finder. Google SSY-1. He's even lying about the power. It's closer to 10kW peak, but even that is deceptive, because pulsed lasers are measured in joules. His was about 1 joule per pulse, and requires many seconds if not many minutes to recharge.

Quote:
 Originally Posted by TSLexi I have enough energy to operate at least the laser itself, assuming 20% efficiency in converting electrical to optical power.
Supercaps operate at very low voltages, and cannot be charged or discharged rapidly, let alone at 200ns. How do you propose to shorten the pulse length and step up the voltage instantaneously and simultaneously?

Do you have a CO2 laser head?

What do you intend on using for mirrors?

How do you propose cooling a gas with a peltier?

How are you going to interface megawatts of peltier with the gas?

How are you going to power megawatts of peltier?

There are no realistic answers to these questions.

Quote:
 Originally Posted by TSLexi call me stupid if you think that's appropriate
You're stupid, lexi.

Not because of what you know, but because of what you think you know. You're thinking in terms of energy ONLY. There are many other factors to consider, and you're ignoring all of them. Enthusiasm is great, but enthusiasm alone makes you look foolish.
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10-27-2014, 09:23 AM #3
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TSLexi
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Re: Building a pulsed CO2 laser

Quote:
 Originally Posted by Cyparagon It is NOT invention, it is a device from a tank's range finder. Google SSY-1. He's even lying about the power. It's closer to 10kW peak, but even that is deceptive, because pulsed lasers are measured in joules. His was about 1 joule per pulse, and requires many seconds if not many minutes to recharge. Supercaps operate at very low voltages, and cannot be charged or discharged rapidly, let alone at 200ns. How do you propose to shorten the pulse length and step up the voltage instantaneously and simultaneously? Do you have a CO2 laser head? What do you intend on using for mirrors? How do you propose cooling a gas with a peltier? How are you going to interface megawatts of peltier with the gas? How are you going to power megawatts of peltier? There are no realistic answers to these questions. You're stupid, lexi. Not because of what you know, but because of what you think you know. You're thinking in terms of energy ONLY. There are many other factors to consider, and you're ignoring all of them. Enthusiasm is great, but enthusiasm alone makes you look foolish.
I just got the tube from a friend, and I'm searching for an appropriate head. Does HyperTherm make good products? I intend to use Mo mirrors.

I'm going to use Freon or water cooling, as I just remembered I do have a 7 L/min pump, and I can keep the reservoir cooled with a Peltier.

In terms of pulsing the energy, I've decided to use a Q-switch.

I could use the ultracapacitor to power a 200 Hz LC oscillator, and send the output of that circuit to a step-up transformer to excite the laser.

10-28-2014, 01:05 AM #4
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Cyparagon
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Re: Building a pulsed CO2 laser

I tried.
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10-28-2014, 01:21 AM #5
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crazyspaz
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Re: Building a pulsed CO2 laser

Quote:
 Originally Posted by Cyparagon I tried.
A valiant effort. I'm sorry sir, but this one may be beyond help. You have done what you can.

10-28-2014, 02:04 AM #6
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swamidog
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Re: Building a pulsed CO2 laser

you could possibly use an AOM to q-switch it.

here's some helpful information to get you started: http://cdn.intechopen.com/pdfs-wm/24808.pdf

10-28-2014, 06:39 AM #7
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The Lightning Stalker
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Re: Building a pulsed CO2 laser

Have you looked into thermoacoustic or
magnetic refrigeration? I've heard that
can get you down to single digit Kelvin
temperatures.

You may also want to consider the effects
of stray magnetic fields on the excited
plasma discharge and subsequent mu metal
shielding to possibly achieve intracavity
laminar hypersonic mach diamonds.

This could be a new area of research into
master oscillator power amplification in
the CO2 regime.
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10-29-2014, 03:13 AM #8
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TSLexi
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Re: Building a pulsed CO2 laser

Quote:
 Originally Posted by The Lightning Stalker Have you looked into thermoacoustic or magnetic refrigeration? I've heard that can get you down to single digit Kelvin temperatures. You may also want to consider the effects of stray magnetic fields on the excited plasma discharge and subsequent mu metal shielding to possibly achieve intracavity laminar hypersonic mach diamonds. This could be a new area of research into master oscillator power amplification in the CO2 regime.
That makes absolutely no sense.

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