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Largest Helium Neon laser in the world (SP125A)

lasingfox

Member
Joined
May 2, 2020
Messages
68
Points
18
sooooooo,

I picked this behemoth up for free nearby and I thought i'd share its journey.

It originally came from the university of california and survived the trip in the back of a truck all the way to massachusetts!! some guy was moving out and thought it deserved a good home and I offered to pick it up. it was non lasing a year ago when he tested it but i thought it'd just be misaligned. I picked it up along with a lexel model 75 but that's another story.
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I finally got back to my dorm and gave it a good scrub since it had maybe 50 years worth of dust in it.
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So, after bringing it up to the fourth floor with some help, I powered it up...
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yea.. filled with hydrogen.. soo, i ran it for a few hours in hopes of it cleaning up and then I started to notice a slight color change.
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until suddenly..
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after that cleanup, its up to 88mW!!!!! absolutely insane. and it can also do a ton of 612nm with external optics. i'm working on getting a new OC to tune to orange in normal operation.. did i mention it has a tuning prism?
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Last edited:



farbe2

Active member
Joined
Oct 3, 2018
Messages
134
Points
43
Nice safe! Good work!
Time to see some orange photons, gas is still way better than solid state. This is such a nice crisp beam and a cozy space heater too :D
 

Sowee7

Active member
Joined
Feb 1, 2021
Messages
222
Points
28
sooooooo,

I picked this behemoth up for free nearby and I thought i'd share its journey.

It originally came from the university of california and survived the trip in the back of a truck all the way to massachusetts!! some guy was moving out and thought it deserved a good home and I offered to pick it up. it was non lasing a year ago when he tested it but i thought it'd just be misaligned. I picked it up along with a lexel model 75 but that's another story.
image0.jpg

I finally got back to my dorm and gave it a good scrub since it had maybe 50 years worth of dust in it.
clean.jpeg


So, after bringing it up to the fourth floor with some help, I powered it up...
image0.jpg
image0.jpg
image0.jpg

yea.. filled with hydrogen.. soo, i ran it for a few hours in hopes of it cleaning up and then I started to notice a slight color change.
image0.jpg
image0.jpg


until suddenly..
image0.jpg
image0.jpg


after that cleanup, its up to 88mW!!!!! absolutely insane. and it can also do a ton of 612nm with external optics. i'm working on getting a new OC to tune to orange in normal operation.. did i mention it has a tuning prism?
image0.jpg
DSCN1721.JPG
image0.jpg
image0.jpg
image0.jpg
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not try and get some 594!
 

Laserbuilder

Active member
Joined
Dec 4, 2016
Messages
197
Points
43
That is a very cool find! Biggest russian He-Ne laser could do not more than 70 mW on 632 nm multimode.
 

Sowee7

Active member
Joined
Feb 1, 2021
Messages
222
Points
28
brand new they can do about that with the RF module yea. i'm just amazed its doing almost 90mW after being practically dead to hydrogen.
where did the hydrogen go, the discharge turned bright orange somehow?
 

Laserbuilder

Active member
Joined
Dec 4, 2016
Messages
197
Points
43
The getter absorbed hydrogen. Getter is activated from the heat of the discharge in the laser tube.
 

paul1598419

Well-known member
Joined
Sep 20, 2013
Messages
18,879
Points
113
Great save! Congratulations on getting this for free. And, considering its age......not bad at all. I have 6 HeNe lasers myself. I had been using them since 1980 to make holograms. I thought I might start doing that again, but need a sturdy place to do that as vibrations and air currents will ruin holograms.
 

icecruncher

Well-known member
Joined
Jan 2, 2008
Messages
1,485
Points
83
someone just gave away one of them on the east coast. I just about snagged it, but decided, I don't have the room, or facility to take proper care of it. Those are awesome, but huge lasers. You NEED to run it on a regular basis to keep it happy. Very few of them are running anymore because of that. Glad you were able to bring it back to life.
 

kecked

Well-known member
Joined
Jun 18, 2012
Messages
660
Points
63
If you ever get I. Trouble with it look up dale@hhr-lasers.com. He has refurb several. Expensive as it needs lots of helium3 which is rare and 2500 a liter plus special neon isotopes. 22 I think.
 

lasingfox

Member
Joined
May 2, 2020
Messages
68
Points
18
someone just gave away one of them on the east coast. I just about snagged it, but decided, I don't have the room, or facility to take proper care of it. Those are awesome, but huge lasers. You NEED to run it on a regular basis to keep it happy. Very few of them are running anymore because of that. Glad you were able to bring it back to life.
oh don't worry. i plan to run it periodically along with my ions. i'll die before i let this thing die :)
 

WizardG

Well-known member
LPF Site Supporter
Joined
May 9, 2011
Messages
963
Points
93
I miss mine :-( The last attempt to regas the beast did not go well.
 




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