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ArcticMyst Security by Avery

External cavity fun

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So I got all my optics and tools in, and I've been playing with external cavities all day.

I was using a 1% pass at 491nm optic on my 488nm single line.

Got this ;)

gbjh.jpg


More to come with more experiments.
 





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Aug 21, 2009
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we should try that trick on my 7 line. ;)

So I got all my optics and tools in, and I've been playing with external cavities all day.

I was using a 1% pass at 491nm optic on my 488nm single line.

Got this ;)

gbjh.jpg


More to come with more experiments.
 
Joined
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Messages
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There has been some work done with that. Someone here got I think 9 lines from there multiline. Just have to have the right optics.
 
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i may have access to the right optics. i'll give it a try tomorrow, if i do.

until then:

reliant-lines.jpg


There has been some work done with that. Someone here got I think 9 lines from there multiline. Just have to have the right optics.
 
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Joined
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Such large dots :p

I will probably have to get an ML eventually. I know there are some tests that I need to run on one. Just needs to be a decent quality, self respecting tube.

Just recently got a book case to invest on some vertical space, so I can no longer complain about space.

EDIT: 8 lines from a 6 line. Used a pass blue, reflect green. Used it to get the two green lines. Although you're just missing one of the 470's. Can't tell from that pic... You have everything else in the normal spectrum from 457-514, so I'm not sure what else you could get. Perhaps 454. Or if you're super lucky, and your tube was specially made, 528nm.

http://laserpointerforums.com/f43/alc60x-argon-extended-cavity-more-green-73333.html
 
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528 only seems to show up at stupidly high currents. I've never seen it in a small air-cooled. My HGM can do 528, but it needs >25A tube current. Strangely enough, I've got a spectrograph, but no picture :thinking:

Laser-Argon-HGM34Alog.png
 
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528 is a tough puppy to lase.

It's not that it needs high current, just very clean optics, and a precise gas fill. If I recall, a trace amount of Neon needs to be present for it to lase with any accuracy. Beyond that, it's really hard, and takes a bit of luck.

However, it is possible as you can see to get it without the Neon, just takes care. My texts mention that with very clean optics, and decent alignment, is it doable.

A snippet from the FAQ where Steve Roberts (Mixed Gas on PL, and LSRFAQ on LPF) speaks on the matter.

(Steve Roberts) said:
I wanted 528 nm from an argon ion laser. I'd only seen it once in a huge Laser Ionics tube at very high pressure. Strangely, that tube had a more or less orange glow at the cathode sheath, much more orange then normal. Now I know why. After a year of research and wondering if my prism was walking out of alignment when cranked to the 528 nm position, I found the solution in a old gas laser text the library was throwing out. It turns out you need a trace of neon in the tube to get the right upper state. No wonder 528 is always labeled "special testing required" from the manufacturer.

PS. Ar also has a 78nm line from the decay process of the electrons to ground state. It's labeled in a few of my tests as a special interest project. However, I would need to find old HR's from used UV AR II/III heads, or from an old 325nm HeCd. Also, I would need sunscreen. If that would even help that deep in the UV. WAY more dangerous that A/B/C as it is much further down the spectrum.

Danger has never stopped me though. Except when I wanted to build an X-Ray machine. Though that's another story.

If a certain someone is reading, how good is krypton at seeing the innards of a circuit board? ;)
/end_inside_joke
 
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LSRFAQ

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Ground state does not lase. Its just a spontaneous emission, and its at 178 nm. It won't make it through the end mirrors or Brewster windows on a stock tube. Usually a thin layer of Halfnium Oxide is deposited as the coating nearest the plasma on the mirrors, and some times on Brewster windows, simply as it reflects that wavelength, yet does not sputter off under the discharge. The Halfnium oxide is one of the few materials that will withstand those conditions.


The plasma will re-adsorb much of the incoherent intracavity light, and turn it to far IR heat.

The other way to catch 528 is to use a intracavity prism, to suppress the competition from the 514.5 line. You still need a brand new, longer, tube to achieve any power from 528. 528 is the only visible argon line to show major gain competition effects.

There is also 1090 from Argon, to try for.

My record is 15 lines from one ion tube, all at the same time. This was a HGM-5 (of all things) with very high quality brewsters, and a special gas mix. Good luck catching up. :)


Steve
 
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I actually made a mistake, I meant 72nm. It's a radiative decay line from Ar's 4s levels decaying to ground. (ref. "Gas Lasers" pg.512)

Either way, I'm not really going for it too much. It'd be a neat test, but either way the Haflnium will absorb it. How efficient is this process? How much bleeds through any way?

How would using an external cavity prism work for the 528? There would still be resonation of the 514.5nm line within the internal cavity, so I'd expect competition to still brew. I'm also not willing to attempt cleaning the mirrors on my 532 to see if I can make magic happen. It's got 4333 hours already anyway, so it's not a very hot tube.

Might try for the 1090 if I can get my hands on some HR@IR optics. Sam doesn't have any for IR tubes, but I haven't searched for Kr HR's yet. Except the very expensive $80 mirrors, and the one you linked me too. Unfortunate, but I haven't been able to use that one yet. I don't have an adapter for a mirror of that size..

I also take that as a challenge ;)

Most I've gotten from a HeNe is 7, good luck catching up :)
 
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What would you need to setup a external cavity? I'd be curious to see if I could get another line or two out of my ML. I have two PJ optics kits from DTR if they'd have anything useful in them.
 
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What would you need to setup a external cavity? I'd be curious to see if I could get another line or two out of my ML. I have two PJ optics kits from DTR if they'd have anything useful in them.

I'd recommend actual optics.

That being said, there was someone that used a pass blue/ reflect green dichroic to get the 501.7 and 514.5nm line out of their (once 6 line) ML.

A setup will need a mirror mount, adapter, and a mount for the mirror mount that will be stable. You need it to not move a micron after you make your X and Y adjustments. Without a base for the mount, you'll adjust X/Y and it will rock once the pressure of your adjustments is gone, thus taking it out of alignment.

It's hard, but I've done it by wrapping a .5in optic in cardboard, and then electrical tape. I got a near perfect alignment, but it wasn't something to write home about, and you just had to look at it funny for it to misalign on its own accord.

Talk to Sam, or get a small breadboard off ebay or Thorlabs.

Let me know if you've got anymore questions :)
 
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It's not much to look at, but here's an orange line lasing on my Spectra Physics SP-127 using a dichro that reflects red/yellow

P1010228.jpg
 
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Nice! I am looking to get my hands on a well off 127 soon :)

Is your krypton for sale?
 




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