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ArcticMyst Security by Avery

A Gas Laser Primer For the Noob

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So, I've got some experience in handheld lasers, know a thing or two about theory. But, it's time for me to make the leap into gas lasers.

Please, use this thread to share to the noobs out there, like me, what they need to know, the faqs to read, understanding optics, dichroic mirrors, etc.

This gas forum needs a sticky worthy introduction to gas lasers in general and links to where to learn more.

I appreciate the members' willingness to share their valuable information and resources with the forum.
 





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My only source is Sam's Laser FAQ...and LPF.

I'd recommend getting a 633nm in the beginning, don't want to get too crazy. There are plenty on fleebay, just make sure it's working. Also try to get the right PSU, with 633 it doesn't matter too much, though it's a good habit to get into for the other wavelengths. If you want to advance, try getting a higher powered 633nm. Some good higher powered ones are the Uniphase 1344P, 1345P, 1345 or the Melles Griot 827, 831/931, and the 927/928. Stay away from SP lasers like the 125A and 127 unless you see it operating. The 125A are RARELY operational. As far as the 127's, SP-127's are often operational, that is if the tube is physically ok and not broken. That being said, the PSU is also questioned, and these don't often meet spec, so it's a bit of a gamble.

Next I'd throw in 543nm. Or GreeNes. They show up, infrequently, in the B/S/T section, and all over the classifieds section of the FAQ. They frequently have 12V PSUs, so keep that in mind, don't plug that into the wall...I've done it, doesn't smell good at all. These are fun when comparing to a low powered 532 because it makes it look a little like colored. Slightly yellower. I've got an 18-24in tube, not too sure, but it's a lot of plasma. By far the most aesthetically pleasing tube I have when running, lots of plasma. These don't tend to output too much. 2-3mW max generally is a pretty high output tube. Though they're notably very visible as you'll see when you get to them. That's to be expected as its very close to the peak at 555nm. Just don't zap yourself with these open tubes, got myself twice yesterday messing with my 612nm REO.

Once you get the basics, feel free to look around for a 594, Sam is just about the only source for them..you could try searching for model numbers on fleebay, I do that to get some gems, but they're infrequent. These also don't output too much without tossing around a pretty penny. I don't want to talk about the price tag of my 594nm LYR. If you want to search fleebay for these, your keyword is LYR. Sometimes though it just takes an eye for finding what doesn't look normal. That just comes with looking at thousands of fleebay items and what they normally are/look like.

Next I'd put the oranges, 612 and 604nm. Good luck on the latter of the two. For 612nm, I'd recommend Sam again, or wait for the usualy biannual one to pop up on the forums, again, psu is everything. For these, search LOR. Again, you sometimes just find something odd when searching HeNe laser. It's a gamble though. These you WILL pay a pretty penny for, regardless. I paid $500 for my 2mW 612nm and that was before it was known to be ML. These are very hard to come by, not nearly as frequent as 633 or 543, even harder than 594. Though they ARE stunning ;)

For 604nm....good luck. You're only get single line 604 out of a REO tunable, or a DIY tunable made from a 1B tube, though it's still hard to get. You're more likely to get this from an ML unit. Even then you're only getting it from a >$400 594 or 612nm. It does feel exclusive having it though. It's a special feeling. For the true wavelength hunter ;)

Multilines are something to always check for. Just make sure you've got the perfect psu, then stick a diffraction grating infront of the output. Got nothing? Let it warm up a bit, who knows.

Lastly, infrared. Again. Good luck. I'm still looking :whistle:. You've got 1523nm and 3391nm. I'd say the 1523nm line is much more common. I let one slip on fleebay a while ago, it was in a mass HeNe lot and by the time I messages them about buying it separately, they already had. So good luck to that person! These don't always work either, so these are quite the journey really.

And that's all I've got! I don't know enough about argon to even try, that's Dave's game. Also didn't mention Raman or tunable lasers as they're still pretty new to me.
 
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Haha, no worries. Wish I could've said more about tunables and Ramans, but I don't know enough from hands on work to really provide anything:
 
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The Ramans I don't know much about, other than getting ones with strong enough lasing lines is rare.

As for tunables there are two kinds: intercavity mirror/prism and single/double Brewster tubes. The single or double Brewster tubes require that you have appropriate mirrors (a wideband HR and various OC is an option) and properly align them to the tube in order to get output. The intercavity prism models simply function like any other tunable laser; you rotate the prism to select which wavelength gets bounced by the wideband mirrors and that is the one that it outputs. The nice thing about Brewster tubes is that the intracavity optical power can be in the TENS of watts or higher for low power <5mW tubes. So if you extend the cavity by placing the mirrors away from the tube you can get a stunning high power beam exposed.

Brewster tubes are often used for particle counting as the intracaivty beam's intensity is enough to ensure good counting while avoiding the need for a truly high power laser. Unfortunately they tend to be more fragile and of course need a solid optical workbench to get running as alignment is a nightmare as always.
 
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Good addition!

Ramans seem to be fairly foreign around the forum, not many really even knew what it was besides a heap of metal that somehow lases 6 lines. Ha.

I'll try to be as in depth as possible when I start my tunable escapade.
 
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It should be noted that just about any gas can be made to lase, if you pump it hard enough. The question is if the output is worth the effort and complexity needed to get it going. 5kW in for 500uW out isn't much fun.
 
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If I could on a hobbyist budget, I'd use gas to fill the gaps between 543 and 589... Using the tunable N2 for that.
 

IsaacT

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Someone said once that you can get anything to lase, if you hit it hard enough. They even made a Jello Laser(found that out when researching for a speech for my comm class).
 
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You can lase jello by pumping it with a nitrogen laser ;)

CuCl, CuBr, and HeHg ... If I can ever get my hands on one...

They all have their challenges on the DIY end, biggest one being the vacuum within a custom glass blown tube. Once that's covered it's just collecting parts for it.
 
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HeHg should really lase at other lines besides 546nm, and I often wonder why it seems no effort has been given in to getting the other prominent Hg lines to lase. Hg has a wonderful spectrum, not the least of which is in the NUV and UV spectrum, which we are severely lacking in for lasers.
 
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elmo-head-explosion-o.gif
 
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HeHg most notably lases in 567nm and 615nm.
 
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I'd be more interested in the three prime UV lines: 185nm, 254nm, and 365nm. 365nm would be the easiest on optics and tube construction, but 185nm would make an excellent experimental laser as this wavelength easily ionizes oxygen into conduction.

While on the topic of Oxygen I should mention that people have made Oxygen Ion lasers using ArKr parts and oxygen has exceptionally high gain.

Sam said:
Oxygen lases on blue, green, and yellow lines with a cold cathode in a tube basically identical to that for Ar/Kr ion lasers. Oxygen lases in the afterglow like mercury. The journal: Review of Scientific Instruments had oxygen ion laser plans about 12 years ago. Oxygen has very high gain.

Neon Ion lasers operate CW in the UV spectrum, but I can't find any info on construction.
 




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