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Thread: Coherent Verdi issues

  1. #1
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    Default Coherent Verdi issues

    Helping a friend with his coherent Verdi 5 watt, single diode system. He is using it to pump a Ti:Saph system. Basically, no or very little output. It does not even have 4K hours on it. Checked the diode and it’s putting out up to 24 watts so that seems to be fine. Starting to worry it is a bad LBO but we have not popped the top off yet.

    Anyone had any experience with these lasers?

  2. #2
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    Quote Originally Posted by macona View Post
    Helping a friend with his coherent Verdi 5 watt, single diode system. He is using it to pump a Ti:Saph system. Basically, no or very little output. It does not even have 4K hours on it. Checked the diode and it’s putting out up to 24 watts so that seems to be fine. Starting to worry it is a bad LBO but we have not popped the top off yet.

    Anyone had any experience with these lasers?
    Which Verdi? There are many green lasers by Coherent called Verdi, some new, some old, one of which I have a year of operating experience with, as a Post-Doc at another College... Pumping Ti:Saph.. We have a few of them around here too, but not in my direct control any more..
    ~
    Remembering slowly because that was four years ago, but did you go into the user control screen and enable the output?
    Its control interface LCD takes some thinking, especially if your missing an external or internal interlock.
    My memory is a bit strained, but I'm also wondering if you need to be configured for a external chiller interlock or not.. There is one older one here I can access if I ask nicely.
    ~
    Does he have the water cooled baseplate that is a separate piece but sets under the head? No cooling, no green...
    ~
    You may also have to go into the alarm screen to find out what is wrong, it generally does not tell you unless you ask... If there is a temporary fault you have to access a menu and clear it, and there is/was a button press combo for startup, depending on configuration. I remember students getting very frustrated a few times in the startup sequence.
    ~
    Generally the last thing you want to do on older Verdi is pop the lid on the head, it wont help you much if you do, and there is lots of scattered light to think about. Misaligning the pump fiber is not a good idea, and the head is very dust sensitive inside, think laminar flow hood and low humidity if you do.
    ~
    Replacement pump diodes are upwards of 7 Grand plus installation per set. I think early models had a habit of the diodes degrading in wavelength from Aluminum migration but still emitting power.
    ~
    I may or may not have a manual at home, depending on age and model.
    Usually Coherent is pretty good about handing out manuals and data if you 1. actually own it, and two call with model and serial numbers.
    Have you called Coherent's science tech support team? My past experiences border on the amazing when dealing with them.

    Steve
    Last edited by mixedgas; 11-29-2017 at 11:39.
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  3. #3
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    It’s an older Verdi V5 with the cooled baseplate. The chiller for it is working, we did check that. It was running just last week and then nothing.

    Diode should not be a big deal, they use the coherent FAP modules and i have a couple new new ones around. The manual shows how to replace them.

    No faults in the error page.

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    mixedgas's Avatar
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    Quote Originally Posted by macona View Post
    It’s an older Verdi V5 with the cooled baseplate. The chiller for it is working, we did check that. It was running just last week and then nothing.

    Diode should not be a big deal, they use the coherent FAP modules and i have a couple new new ones around. The manual shows how to replace them.

    No faults in the error page.
    From memory:

    The one I used was old, abused, shop worn, and "fussy" about starting and getting the temps locked.. Once it started it was a solid gold performer till the crappy third party chiller got unstable.
    Fussy Interlocks
    Chiller Temperature must be correct.
    ~
    Baseplate flow must be good and uniform for stability, DI water usage by pervious user caused corrosion which blocked some flow in our external baseplate. I opened it up and remachined the flow passages on a manual mill. That would not stop it from lasing, however.
    ~
    External Serial Enable must work if set for it.
    Fussy Start Button Sequence, easy to enable/disable laser on other setting screens by mistake.
    External flow on before startup.
    Config Screen set for right internal temperatures.
    Autoscan to find correct temperature parameters once in a very long while.
    Did not always enunciate faults clearly.
    Possible dead Memory battery in PSU (I think that was the Verdi, not sure, again four years ago in a high stress environment)
    Shutter setting..
    Rear connectors worn and not seated was an issue
    Often pops an internal fuse in PSU for no reason.
    ~
    That's all I remember right now.. My job was to fix that system, and the previous maintainer rushed to catch a flight to Europe before I told my new boss all that was wrong and damaged. (About 20K$ on the optical table WRT Damage to other lasers and far IR optics damage)
    ~
    Don't get me wrong, Verdi's are about as good as lasers get, and I loved using it. Would love to have one..

    Steve
    Last edited by mixedgas; 11-29-2017 at 12:07.
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  5. #5
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    Quote Originally Posted by macona View Post
    Helping a friend with his coherent Verdi 5 watt, single diode system. He is using it to pump a Ti:Saph system. Basically, no or very little output. It does not even have 4K hours on it. Checked the diode and it’s putting out up to 24 watts so that seems to be fine. Starting to worry it is a bad LBO but we have not popped the top off yet.

    Anyone had any experience with these lasers?
    Greetings
    Reviving this old thread as I am having a similar issue with my Verdi... Were you able to solve the problem in the end?
    Many thanks

  6. #6
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    Might check this video, my friend helped him get his Verdi running. https://youtu.be/fHxvV-PuqP0?feature=shared

  7. #7
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    Thank you Macona
    Nice to see some members are still around after 10+ years

    I know that video, quite a good one in fact. Technical info on servicing Verdis are scarce on the internet.

    Sadly the video does not help much in my case.
    I have a couple of Verdis and have played with them a fair bit.
    In this case it is a V18 which was working fine then its output dropped to 1W or so from one day to the next (admitting I might have played with some settings in between).
    I used the VERDI GUI software in service mode to restore all EEPROM parameters to a date when it was working fine, I manually re-optimized all temperatures and also measured the raw outputs of the two pumping diodes which are fine. Now I am short of ideas of what to test.

    So my symptoms are similar to the ones of your friend with his V5, hence my question if you or he recalls what the problem was in the end?
    Alternatively if you can put me in touch with one of them that would be much appreciated

    --Loic

  8. #8
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    Quote Originally Posted by Loic74650 View Post
    Thank you Macona
    Nice to see some members are still around after 10+ years

    I know that video, quite a good one in fact. Technical info on servicing Verdis are scarce on the internet.

    Sadly the video does not help much in my case.
    I have a couple of Verdis and have played with them a fair bit.
    In this case it is a V18 which was working fine then its output dropped to 1W or so from one day to the next (admitting I might have played with some settings in between).
    I used the VERDI GUI software in service mode to restore all EEPROM parameters to a date when it was working fine, I manually re-optimized all temperatures and also measured the raw outputs of the two pumping diodes which are fine. Now I am short of ideas of what to test.

    So my symptoms are similar to the ones of your friend with his V5, hence my question if you or he recalls what the problem was in the end?
    Alternatively if you can put me in touch with one of them that would be much appreciated

    --Loic
    I think he had a bad diode.

  9. #9
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    Quote Originally Posted by macona View Post
    I think he had a bad diode.
    Interesting. Is it possible then that a diode has the intended output power but still has smoething wrong with it so that the Verdi won't lase properly? Maybe a wavelength sudden strong shift?

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