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Thread: V****o DPSS Green has died, need help...

  1. #1
    Join Date
    Nov 2010
    Posts
    346

    Default V****o DPSS Green has died, need help...

    Hello guys,

    Came the end of the world, In my lovely 4W green laser power suddenly dropped to 0.3 watts. I disassembled the unit and after some research, i found that inside vanadate crystal has a small crack (had to look through a microscope) and on the surface of the LBO crystal has several dark spots. Diode, TEC, is functioning normally. I don't understand why this happened. The second 4W green, which works in tandem with it - works well, no hint of power reduction...
    I have a few questions about the crystals that are used in this module. Probably the characteristics typical of all modules built in China.

    -what's the Nd concentration in Nd:YVO4?
    -what's the coating on surfaces Nd:YVO4?
    -should i be concerned about a few dots on LBO surface?
    -what is the possibility of damage to the front and rear mirror/lens?

    And the most important question - where to buy good crystals for replacement?
    PS: vanadate size - 3x3x5mm LBO size - 2x2x10mm

    This is my first experience with a powerful DPSS, so I will be glad to hear any useful information.

    Thanks!

  2. #2
    Join Date
    Feb 2005
    Location
    Switzerland
    Posts
    1,410

    Default

    Hi,

    How old is the laser? (Years/hours)

    Have you tried to contact Frank at Viasho? He's responding fast and he will quickly sort this out for you...

  3. #3
    Join Date
    Nov 2010
    Posts
    346

    Default

    Hi,
    laser about two years old, but the mileage of about 100-150 hours. Second laser with the same mileage working like new.
    I contacted with Frank, he offered me the crystals, but I want to "find out the reasons" before spend a heap of bucks to repair...

  4. #4
    Join Date
    Feb 2005
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    Switzerland
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    Default

    Ok strange, but I think the reason is simply "chinese cheaper laser", so defects happens, with every manufacturer.

    But my guess about the best thing to do is you should happilily send it back to the factory so they can properly repair it, as you don't want to do it by yourself until you have a lot of experience in high power DPSS alignment, and patience...

  5. #5
    Join Date
    Jun 2009
    Location
    Nebraska
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    Default

    Those could be thermal stress induced damages. Might want to triple check your TEC operation and verify its working ok.


  6. #6
    Join Date
    Feb 2011
    Location
    New Hampshire
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    I agree that you might just want to send it to Frank. I think if the TEC were working so poorly that you produced thermal fractures then you should have seen some degradation in alignment and output. I also have a Vashio (1.5W) that "died and then generated only 50mW after only the first 10 hours of use. Frank returned it to the factory for a new head and no problems for the last 16 mo.

  7. #7
    Join Date
    Nov 2010
    Posts
    346

    Default

    But my guess about the best thing to do is you should happilily send it back to the factory
    Yes, of course. If it was under warranty, I would have done so. Otherwise, I need to pay for shipping, parts and work, I think that it will harm my budget around 1k$
    Those could be thermal stress induced damages. Might want to triple check your TEC operation and verify its working ok.
    I checked four times - temperature stable about 22C

    This forced me to drink coffee and think ...
    Of course, I was wrong about the LBO crystal. It's a KTP crystal, they used by many manufacturers at a pump power up to 15W. I has bungled a simple drawing of my laser:

    Attachment 35210

    Trying to shot the crystals. This KTP, clearly visible dot on the surface, which worries me:

    Click image for larger version. 

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    And this is the main culprit - Nd:YVO4 crystal. Can see crack? Formed from overheating?

    Click image for larger version. 

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    Preliminary verdict - replacing Nd:YVO4 crystal - 100%, KTP - 50/50
    Oh, I almost forgot - I have tried to re-collimated and I managed to find the location of optics in which laser gave 2 watts.
    Last edited by Bbe; 10-16-2012 at 01:00.

  8. #8
    Join Date
    Jun 2009
    Location
    The Woods, CA, USA
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    534

    Default

    Great pics thanks for the posts Bde.

  9. #9
    Join Date
    Jul 2010
    Location
    Brazil
    Posts
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    Iīm having the same problem here two units, (2w) from Viasho are now very low power... do you think I can try and fix them? Replace the crystal (what source)?
    I live in Brazil and it is almost impossible to send it back, would end up costing a new headīs price =/

  10. #10
    Join Date
    Jan 2007
    Location
    Florida
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    Default

    I think I read somewhere (probably a Steve R post) that you can sometimes find / realign to a different (undamaged) area on the damaged xtal and get it back to good working condition . I don't know if your laser has that flexability/ capability tho ..

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