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Thread: Help me describe how bad this is...

  1. #1
    Join Date
    Jun 2008
    Location
    Orange County, CA
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    233

    Unhappy Help me describe how bad this is...

    One week my ND:YAG Laser was working perfectly. The next week...

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    This is a picture of the laser when is was working:

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    Yes, I failed to check the TDS of the cooling water before engaging the ALE power supply.

    You can't even imaging how my stomach feels :-(

    I'm going back to argons...

  2. #2
    Join Date
    Feb 2005
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    Switzerland
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    1,392

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    Omg, how could the rod been that much damaged?? I had up to 5 YAG engraving lasers at work, changed the lamps many times and yes they tend to explode, but the rods never got hurt...

    Sad, good luck with argons now

  3. #3
    Join Date
    Nov 2007
    Location
    SoCal / San Salvador / NY
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    4,019

    Lightbulb

    Quote Originally Posted by sbk View Post
    ..how could the rod been that much damaged??
    ..cuz it's not.. The Rod is the 'frosty-white-lookin' thing.. That just looks like a classic lamp / flow-tube (?) suicide.. Old hat for us LS-jockeys..

    EDIT: On-closer zoom, Mmm, ya.. looks like there *might* be rod-fractures, too.. Hard to tell w/ all the lamp-shards, but.. Eeek, looks.. not-so good... Condolences, if it's as-bad as it looks.. :/

    Sir W - Got specs on that lamp / Rod? Shoot me a PM, I'll see if we can get ya fixed up..

    (..but, if ya DO-decide to 'go back to Argons', I've got a niiiice 171 Ar doin' 22W, FS... jk..

    j
    Last edited by dsli_jon; 02-28-2015 at 00:09.
    ....and armed only with his trusty 21 Zorgawatt KTiOPO4...

  4. #4
    Join Date
    Jun 2008
    Location
    Orange County, CA
    Posts
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    Yes, both the lamp and rod are "toast."

    I only have dimensional specs on the arc lamp and YAG rod:

    Arc Lamp:

    210mm (8.27 inch) overall length
    8.1mm (.316 inch) outside diameter
    96mm (3.78 inch) arc length
    175mm (6.89 inch) quartz envelop length

    YAG Rod:

    110.6 mm overall length
    6.31 mm diameter

    Yes, if you can provide the specs on the arc lamp and YAG rod, such as part numbers, that would be very much appreciated.

  5. #5
    Join Date
    Apr 2007
    Location
    Costa Rica
    Posts
    523

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    Sorry to hear. I had a L-scope that was actually lasing with a broken rod. Not a lot of power, but still, they are quite efficient compared to argon.

  6. #6
    Join Date
    Jan 2006
    Location
    Charleston, SC
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    Bad day, that's for sure!

    If the lamp exploding was bad enough to smash the flow tubes AND the YAG rod, you may have also ruined the gold-plating on the cavity... Be sure to inspect that once you clean up all the shards.

    Still, worst case you're talking a new lamp, new rod, new cavity, and a pair of flow tubes, plus a new DI cartridge to keep your conductivity nice and low where it belongs. Not exactly a cheap fix, but all those parts are readily available on the surplus market.

    Adam

  7. #7
    Join Date
    Jun 2008
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    Orange County, CA
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    Quote Originally Posted by buffo View Post
    If the lamp exploding was bad enough to smash the flow tubes AND the YAG rod, you may have also ruined the gold-plating on the cavity... Be sure to inspect that once you clean up all the shards.

    Still, worst case you're talking a new lamp, new rod, new cavity, and a pair of flow tubes, plus a new DI cartridge to keep your conductivity nice and low where it belongs. Not exactly a cheap fix, but all those parts are readily available on the surplus market.

    Adam
    Fortunately the gold plating is still pristine and the flow tube around the YAG rod is intact. I don't know if their was a flow tube around the arc lamp.

    To avoid this kind of accident in the future, I am planning to install an inline Total Dissolved Solids (TDS) meter like this one from The Filter Guys (I have no association with the Filter Guys):

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    Any opinions on this device for a ND:YAG laser application?

  8. #8
    Join Date
    May 2009
    Location
    UCSB
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    Your best bet at this point is probably to just buy a fresh laser (laserscopes, they are down to a few hundred bucks these days, and have an almost identical yag assembly in them). That is one nice thing about playing around with lam pumped yags, there are plenty of them floating around to scavenge parts off of. If you think you have it rough, stay away from diode pumped yags, a fresh stack of diodes for a laserscope starts at $2k for a used one

    As far as the TDS meter goes, I just use a normal conductivity probe but it is hard to beat the cost of those meters. You are definitely going to need a DI cartridge in the loop if you do not already have one, you might also need to replace your tubing since the tube in your system now looks pretty questionable. You should also try to use black tube for DI water loops if you can, algae loves to grow in any part of a DI loop that is exposed to while you are storing the system.

    That said, the failure that you describe does not look like a water purity issue. The fact that the yag rod cracked inside its still intact flow tube tells me that it failed due to a low flow or thermal shock condition. What sort of rig are you using for the cooling? Those suckers need at least 1GPM, ideally a fair bit more (A normal laserscope runs about 2gpm IIRC).

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