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Thread: LGI-40 russian xenon ion laser

  1. #11
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    mixedgas is offline Creaky Old Award Winning Bastard Technologist
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    I need to look at the glass structure later today, but you may go in thru the fill system and just need to heat the tube to almost 100c to get any water vapor that has leaked in. I see some nitrogen and water in the plasma, but not much. Probably an ultra slow leak
    At the window seals.

    If you can go into the resivoir, the pumping time is long , it will need many flushes of gas, but odds are you will not need new electrodes.

    Steve

  2. #12
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    Today I've made the power unit fully operational. After that I learnt from scientific articles that in most lab-manufactured Xe lasers the electrodes are made of indium. I was wondering what was the metallic filling in the side arms of the electrodes in my laser tube, it looked like it had been poured inside when molten. After reading some articles I am pretty sure that this is indium, as it has quite low melting temperature. It is said that indium acts like getter and absorbs gases including xenon. It is responsible for rapid depletion of it.

    After all I fired the laser tube from its power supply for a minute or two. It flashes with white-green colour at low voltage an white-blue-violet at high voltage. The discharge emits a lot of UV that makes air smell with ozone. The discahrge colour very much looks like a mercury arc lamp.

    No lasing was observed in the operational range of voltages and PRR. I did not check the mirror alignment, thinking that it is not so critical because this is a pulsed gas laser.
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  3. #13
    mixedgas's Avatar
    mixedgas is offline Creaky Old Award Winning Bastard Technologist
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    Well that is a Xenon spectrum...
    Looks like you bettered the n2, o2 and water vapor.

    Steve

  4. #14
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    I expected the discharge colour to be more neutral white though. It looks like a low-pressure mercury arc lamp...

  5. #15
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    I've checked the mirrors and they were out of alignment. So, after alignment this device eventually lased GREEN.

    Unfortunately, because of my idiotism and laziness the laser died soon. The tube cracked after 2 minutes because I didn't attach water cooling, hoping that fused quartz tube will withstand thermal stresses as it is described in literature. And it really does, because I welded a quartz spiral condenser with a hydrogen glassblowing torch without uniform heating of the whole workpiece and proper annealing as it is required while working with conventional glass. This condenser is still working fine. This is an incredible loss for my laser collection because the tube is beyond repair now and I will never get the same one. Making a custom tube is probably very unprofitable for some tens mW of green light. I even don't know wether it lased on many lines or on a single one, but the mirrors look like broadband. the beam looked very much like 532 nm, so possibly it was a 535 nm line.

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  6. #16
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    Dale@hhr-lasers.com. He can make a new tube.

  7. #17
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    Everything turned out to be not so fatal. The damage location allows to repair this tube without a total rebuild. I will have to cut off the part of the wide flask with the Brewster window at one end and then seal the hole on the joint of the central tube and the internal water jacket. After all The flask with the Brewster window has to be welded back and the tube integrity will be restored. Vacuuming it and refilling with xenon is another, long and complicated issue. Possibly my fellow glassblower will be able to fix it.
    Last edited by Laserbuilder; 11-20-2017 at 11:52.

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