Spectra-Physics 127 find

[HD58PHD]

Hi all,just picked up a 127 HeNe off KSL here in Utah. It is intact,tube fires right up nice and bright,no lase. I've been to Sam's and still have some concerns before I start fiddling with mirros. It has Brewsters at both ends bellows intact.
The plasma runs from the side mounted cathode through the capillary to anode. Plasma never goes towards mirrors,how is that to lase? I've seen pics of lasing 127s that show same thing.
It runs for hours so guessing gas is good,what should I try first?
Mike

[mixedgas]

Plasma looks like a good color in the second picture. Not so great in the first. With the caveat that cell phone cameras can be deceiving because of IR..

Unless the previous owner ( or typical university LSO) detuned it for safety, odds are the slightest touch of typically the rear mirror horizontal adjustment will restore lasing. The Brewster window is typically, if not always, in the horizontal plane on those. Mark the nuts with a pencil before turning.


I'd start with a slight touch of the Allen Screws. A very slight touch. Other thing, if setting on a shelf for years, you may get a little diffraction from bore sag.

Plasma touching the tube windows is generally not a great idea.

Hoping for DZ to chime in soon. He loves those. I prefer the Siemans units to play with.

Steve

[HD58PHD]

Hi Steve,the Allen screws being the bore supports,and touching not turning?
And diffraction would require lasing first? Or not?
Diffraction being a beam touching the bore?
Am looking to try setting up an alignment jig with info from Sam's,gotta wait till there's no foot traffic on the sidewalk at night.
Mike

[mixedgas]

Leave the bore alone.

On 127 there are fine adjust screws using Allen' Screws on the mirror mount. Looking at your picture that mount may not have them, inwhich case you have a "909" resonator in a 127 head.
I'll take a picture later today.

Steve

[HD58PHD]

I don't see any fine adjustment screws,just the spring loaded 11mm nuts. If I can get a beam straight down the bore from a HeNe or GreNe is that an option? I also have my argon.

And can I safely remove the OC/mirror mount? No risk of breaking anything when I push the bellows off?

Mike

[mixedgas]

I don't see any fine adjustment screws,just the spring loaded 11mm nuts. If I can get a beam straight down the bore from a HeNe or GreNe is that an option? I also have my argon.

And can I safely remove the OC/mirror mount? No risk of breaking anything when I push the bellows off?

Mike

the bellows is likely to rip. no reason. not to remove the front plate, but you may find it easier to just remove the front mirror.

[HD58PHD]

Thank you for your help,just need to clarify, do you suggest I remove the mirror from the center of the black plate? By unscrewing the retainer ring?

Mike

[mixedgas]

Thank you for your help,just need to clarify, do you suggest I remove the mirror from the center of the black plate? By unscrewing the retainer ring?

Mike

Yes, unless the brewster windows are absolutely filthy, it is best just to remove the mirror, or only one end of the bellows. However, after many years of exposure to UV, the bellows can make dust.
Its a judgement call on removing the bellows. I am not familiar with the mounting structure on your unit, but if possible avoid removing the bellows or touching the coated face of the mirror.

The mirrors will retain moisture, so best to carefully check for films by examining the mirror with a bright, bright, light at a glancing angle. I get the alignment plates close to alignment from measuring to the frame end to a mirror plate with a digital caliper.

https://www.amazon.com/Jiayouy-Sucki...%2C114&sr=8-10

If you can find a brand of suction tool that works, these are great, but put a soft pad between the end of the laser and your hand, in case the optic drops. They tend to release inadvertently, which is why pros make a grooved tool to catch the optic right next to the plate if the suction fails.

Take pictures of the stack of washers, the Belleville spring washers can go on in quite a few patterns, but only one is right.

Steve