🚀 go-pugleaf

In article <1992Aug26.194917.734@cs.ucf.edu>, clarke@acme.ucf.edu (Thomas Clarke) writes...
>In article <massoud.57@chemteca.sdsu.edu> massoud@chemteca.sdsu.edu (Massoud  
>Ajami) writes:
>> In article <1992Aug26.043710.27944@vpnet.chi.il.us> cgordon@vpnet.chi.il.us  
>(gordon hlavenka) writes:
>> 
>> 
>> >I have an _ancient_ laser which almost works.  It's a HeNe laser,
>> >model 3100 from Gaertner Scientific (circa 1969).  It worked for a
>> >while, but now has developed an electrical problem.
>> 
>> 
>> You have lost the gas. You woudln't expect helium gas stays in the 
>> tube forever?
>> 
>About five or six years ago I saw a little article in Applied Optics
>about rejuvenating olf HeNe tubes by putting the tube in a chamber
>with pressurized(?) He for a day or so.  

	Also other things happen. Main difference between older tubes and
	newer ones was the quality of the seals between the tube and the
	mirrors on each end. Not just gas leaking out, but atmosphere getting
	in. Some things to note.

	Even if you get a gas discharge, (red glow,) you may not get lasing
	action.

	If you see a blue glow, (looking slightly off axis, and blocking
	the main beam,) this also indicates contamination.

	Many tubes I dealt with contained a getter, but also a black spot on the
	side of the tube which degassed more gas as the tube heated. For new
	tubes the spot was very black. For old tubes, it faded out.

	One last trick, switch polarity on the tube. Cook it this way for
	a couple of hours, then switch back.

   Frank R. Borger - Physicist    __       Internet:  Frank@rover.uchicago.edu
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