# Gas still rules!



## FRITZHID (Feb 8, 2017)

Yes, i know... LD and DPSS lasers have dominated the market but i still believe that gas lasers are by far the better laser, especially in the aesthetics dept...

That being said, i picked up this little gem about 2 yrs ago from an electronics graveyard for $20 but it lacked a PSU  ....





But a well known laser expert sent me this and it arrived this AM...




so now there's this beautiful HeNe discharge that just can't be beat, and the beam is stunning as always with hene...




and of course, the spectral...






after dark, i'll see about some beam shots.


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## BVH (Feb 8, 2017)

ooouuuuuuu aaaaawwwwwgh Purdy!


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## FRITZHID (Feb 14, 2017)

25' beam shot


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## FRITZHID (Apr 15, 2017)

https://www.youtube.com/watch?v=p6AZZn-3kJg&t=51s


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## Dr. Mario (Apr 16, 2017)

FRITZHID, now that's some Helium-Neon laser. I am also surprised that this laser is still functional, as it looks to be made in 70s - 80s. (Ancient Helium-Neon laser tubes tend to be built the weird way as you can notice when comparing this ancient laser tube with modern barcode tubes - nevertheless, it makes for some pretty interesting neon sign in a way. Also, soft-sealed laser tubes tend to die much faster than hard-sealed ones, however yours seem to be vacuum-fit, meaning the seal was formed between perfectly ground tube end and mirror or brewster angle plate in a way they're cold-welded together, which explains its longevity.)

Even though DPSS and laser diodes have conquered the markets, there's still huge markets for gas lasers owing to their characteristics which still makes them attractive, such as time domain stability (spectrum width and coherence length) which is still way better than laser diodes, except for some very expensive VCSEL diodes. That said, I have a few very small Helium-Neon laser tubes (Melles Griot 05-LHR-640), and they are a rather nifty demonstration of optical physics by themselves. I wish I would have a small laser inverter power supply to be powered by a single high-drain Lithium-ion battery - I might have to make one though.


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## FRITZHID (Apr 16, 2017)

Yeah, she's my "glass work" baby.... So beautiful to look at whilst running. (Glad she doesn't hog the dryer outlet like my Ar/Kr!)


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## Dr. Mario (Apr 16, 2017)

It certainly is. The nice thing about Helium-Neon lasers is that they're efficient in comparison to Argon-ion lasers, which is nice because you don't have to worry too much about the electrical and cooling requirement (except for some extremely rare monster Helium-Neon lasers).


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## FRITZHID (Apr 16, 2017)

True. Personally, I love this laser for the fact that it's very easy to use as teaching aid... On many levels. ....and it's beam is so f'n clean! I put any bare laser to compete! Lol


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## Dr. Mario (Apr 16, 2017)

Yup - it's popular for usage as a teaching aid - if you have access to the external cavity Helium-Neon laser as those used in the medical Raman spectrography machine, you can do some nifty optical tricks with it (such as multiple brewster plates between the laser output end and output mirror - when you have set up enough of them the right way, it will resume lasing as if the plates aren't there). 

And as for the clean laser beam, I totally agree, quite crispy compared to the elliptic laser beam typical of the Fabry-Perot (the usual favor) laser diode.

EDITED: Here's a link to the optical trick I talked about, it's under "Perpendicular Uncoated Windows in a Low Gain Laser" in Sam's Laser FAQ link - https://www.repairfaq.org/sam/laserexp.htm


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## FRITZHID (Apr 16, 2017)

This HeNe is a 2 Brewster window laser..... About the best laser you're gonna find for teaching the basics.


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## Dr. Mario (Apr 17, 2017)

Two Brewster windows laser? Excellent, it will work.


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## Accutronitis (Nov 24, 2017)

Rules in what way ? Nice round, low divergent beam ?


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## FRITZHID (Nov 25, 2017)

Accutronitis said:


> Rules in what way ? Nice round, low divergent beam ?



....For starters.


They are works of art, beautiful to look at. Todays solid state lasers are little more then just another electronic module..... a chunk of aluminum with wires to a driver.
HeNe, HeCd, Glass bell AR, etc are aesthetically pleasing, especially when powered... that beautiful plasma glow.
Then there is those few wonderful Multi Spectrum lasers that you just cant get in a solid state device. Ar/Kr for instance, 6-11 separate lines from one cavity, can't see semiconductor cavities doing that anytime soon! lol

Are they less efficient? yes.
Are they large and cumbersome? you betcha.
Are they worth it? ....Absolutely, yes.


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## Accutronitis (Nov 25, 2017)

Cool, Now i get it !


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## FRITZHID (Nov 25, 2017)

Accutronitis said:


> Cool, Now i get it !





:thumbsup:


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