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Ultraviolet TEA laser

L

Lee

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I have been browsing information on how to make a TEA laser. This kind of laser uses the nitrogen in the air as the lasing gas, and sparks discharging from two long electrodes resting on a foil capacitor. Does anyone have experience building one of these? The only part that I am lacking is a 10kV power supply for the capacitor.

Just search "TEA Laser" videos for more info

The ultra violet beam is not that impressive, but this would be a cool project anyway. 8-)
 





resaL said:
I have been browsing information on how to make a TEA laser. This kind of laser uses the nitrogen in the air as the lasing gas, and sparks discharging from two long electrodes resting on a foil capacitor. Does anyone have experience building one of these? The only part that I am lacking is a 10kV power supply for the capacitor.

Just search "TEA Laser" videos for more info

The ultra violet beam is not that impressive, but this would be a cool project anyway. 8-)
Click to expand...

You can always send it through a DYE to get a visible beam I think. I always wanted to make one, but more experience with the little lasers is needed first for me.
 
i built smth that remotely looked like a TEA laser using kitchen Al foil and stationery stuff as dielectric plus some aluminium rods resting along the foil edges to form the discharge laser channel.
- a high voltage source is required to excite the medium
- the spark gap is extremely loud. unless it is a specially desgned one in a suitable enclosure, it would make horrendous rattling every time hundreds of amperes flow thru the air in nanoseconds and emit copious amount of UV light
- capacitor's ability to store charge make the entire setup extremely dangerous even if the HV source is only able to provide microamperes of current
- alignment of electrodes is finicky - ideally they must be parallel and provide the proper gap for the lasing to occur and avoid hot spots /concentrated arcing/ as much as possible
- the contact between all metal parts must result in the lowest possible inductance to enable a rapid discharge thru the spark gap
- when /if/ lasing occurs, the pulse is only ~1ns or less long
using a vacuum electrode chamber with low pressure nitrogen results in longer pulse duration and higher power. oxygen is believed to 'kill' lasing action, which occurs at 337.1nm and is multimode. the beam is very divergent and invisible, but it makes lots of mterials, such as printer paper, fluoresce and the dot can actually be seen.
in the picture you can see the dot projcted on a white sheet of paper 3 meters from the exit aperture. it is dual because of a misaligned mirror behind the lasing channel reflecting the beam off the axis of the channel. normally no optical resonators are needed for this to work. in the other half of the pic is the beam 'energizing' an orange piece of paper only an inch from the aperture. some of the discharge along the channel is also visible.
the HV source is a simple TV flyback xformer, a 1-transistor oscillator and a multiplier. by varying its power supply from 5 to >15 volts it is possible to reach in excess of 25kV DC on the HV side
 

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A friend of mine and I built one years ago. The foil part is the capacitor and we used a 1B3 rectifier tube from a TV set and a neon sign xfmr. BANG,Bang,BANG -- yes it put out a beam which would light a stripe on a T shirt across the room.
Mike
 
Well I'm still intent on making one... I'll look through some more references. In the meantime I'll be looking for neon sign transformer or the like.
 
I see these things aren't really powerfull yet I keep reading that N lasers can be obtained in the kW range....What would you need to make one of those?Or at least one that would be worth the huge power consumption and loud noise. ::)
 
Switch said:
I see these things aren't really powerfull yet I keep reading that N lasers can be obtained in the kW range....What would you need to make one of those?Or at least one that would be worth the huge power consumption and loud noise. ::)
Click to expand...
they can peak in the MW range in fact, but thats for a pulse a few or less nanoseconds long.
i wouldnt say power consumption is huge. u need high voltage, but only a few milliamperes, or even less, to charge the capacitor plates. if higher repetition rate is required, the current has to be raised,though. building a simple home-brew HV PS is not much of a challenge. once you have it, all you need to put together a quick and dirty prototype can be found in any kitchen - Al foil, dielectric/plastic sheets with suitable thickness and dielectric strength and a few metal rods. there are many manuals online on building N2/TEA lasers. the output is not impressive really, but it's strong enough to excite dyes, such as rhodamine, to lase in the visible spectrum.
 
I've built a tea nitrogen laser, is my first laser!! it is very simple and cheap, but requires many attentions to works well: alignment of electrodes, obtain lower inductance and resistance, etc..
If you use simple air, the performance is very low because of the oxygen present: you will see a small unuseful blueish dot on fluorescing paper.
It is true that peak power is high, but in pulsed laser the most important parameter is the energy, measured in Joule or w/s(and in this case is very low).
A way to improve the output is to use pure nitrogen and 50-100 Hz repetition rates. In this case with focusing could be possible to burn something like paper I suppose.
 
resaL said:
Well I'm still intent on making one... I'll look through some more references. In the meantime I'll be looking for neon sign transformer or the like.
Click to expand...
NST are good for this purpose, but be careful! and you may need to rectify the output and/or add a resistor to lower the current.
In my project I used an Helium-Neon(5mW) laser power supply...(but I burned a huge amount of dielectric sheet before get some laser light :o )
 
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