Technical factoid
Someone, somewhere probably needs this information - I have no idea who though...
Everything I've read about helium-neon lasers says that the tubes invariably leak and only last a few years. But I've just noticed that the one we have at work (Uniphase 4mw, originally intended for a medical sensing application) was made in May 1990. We don't use it much, since we're not supposed to use anything above 1mw without a lot of extra safety precautions, but it's still working.
I don't know how this scales up to more powerful lasers, lasers that are in full time use, etc., but it surprised me.
Everything I've read about helium-neon lasers says that the tubes invariably leak and only last a few years. But I've just noticed that the one we have at work (Uniphase 4mw, originally intended for a medical sensing application) was made in May 1990. We don't use it much, since we're not supposed to use anything above 1mw without a lot of extra safety precautions, but it's still working.
I don't know how this scales up to more powerful lasers, lasers that are in full time use, etc., but it surprised me.