On Friday, 7 March 2014 04:32:23 UTC, Jon Elson wrote:
Samuel M. Goldwasser wrote:





This ia an SP-120, probably from the 1970s. And, yes, those old tubes

do leak due to the Epoxy seals. Modern tubes do not leak.

I hate to dispute a known expert in the field, but as you say

this laser may be almost FORTY years old! Yes, the crummy old tubes with

sloppy epoxy seals may have leaked down in a few years, but even the

best HeNe all-glass tubes will eventually lose their He. It diffuses

right through the glass. And, the partially aluminum tubes

leaked much faster, still.

Sam said earlier that it _will_ have lost some He and so that will be at least one of the problems it has. The question then was whether it has air contamination also.

I'm going to try giving the a helium soak, but if it came to having to break the seal, evacuate it, bake out and refill -- well, that's probably beyond me.

Regards,

Andrew