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Thread: KTP532 model 720 by LaserScope

  1. #1
    mixedgas's Avatar
    mixedgas is offline Creaky Old Award Winning Bastard Technologist
    Infinitus Excellentia Ion Laser Dominatus
    Join Date
    May 2007
    A lab with some dripping water on the floor.

    Default KTP532 model 720 by LaserScope

    A friend of mine had a upcoming show. He was loaned a KTP532 with a service rom, that had medical optics removed. quote" Ok Steve when you get here you'll have about 4 hours to install 3 fiber launches and get this thing collimated somehow."

    Yep, like that was gonna happen.

    OK, this thing is dangerous. The software and hardware watchdogs tended to over ride the service mode screen. It would go from a watt or two, with Qswitch RF off and lamp in low current, to high RF and full lamp with no warning, so beware of so called "service" eproms. Imagine having fingers adjusting fiber mounts, and a inch away or less the beam pops up to a full 28 watts of high peak power. YIKES!

    Next, 4 hours is nowhere near enough to engineer a collimator. Others said they used a 3:1 upcollimator just after the prism that seperates the IR from the green, but that doesnt work well. Beam height was a little less then 1.5" to center off the base plate.

    Next up, if your gonna work on one of these, you need a seriously long indoor test range with REAL full range safety precautions. 20 feet was not enough range to accurately confirm collimation. Without good collimation you cant get good power into the fiber, as your basically trying to image a beam waist someplace onto the 100 micron fiber.
    BTW, if it jumps to full power and your focused on the cladding, not the core, wierd things happen, like BLOWING THE FIBER TO SHREDS. I did not experience the classic nonlinear effects of the plasma ball traveling down the fiber sputtering flaming outer jacket all around the room, but we did loose one small short test fiber as I was learning. That pretty much never happens with argon fibers.

    NEXT UP, and real darn important is proper beam termination tools. The scatter from even a black anodized plate is too strong, even with OD5 googles. You need a nested light trap with mazes. BTW, most black anodized parts bleached in that beam. I cannot stress enough the dangers of the IR and Vis leakage on this beast. There is a reason why the built in beam trap has water cooling!

    FULL WRAP AROUND GOGGLES ARE A MUST ! The scatter off any part of this thing is well past any reasonable MPE!

    God, what a nice laser, and what potential! But what a crappy beam. Mode was best decribed as tem 5,10 and unstable. The best I could get was about 5 mm diameter.

    I finally ended up just splitting the beam right after the fold prism and running it into both launches (precision projection inc launches and fiber, 100u fiber)

    lessons learned:

    1. A ktp is trying to kill, mame, burn, or blind you from minute one, and burns occur from the inside out (so I'm told by medical techs.)

    2. 28 watts of qswitched green burns half way through a 2x4 in a few seconds,and does quite a number on plasterboard, MDF, black anodize and tissue

    3. Dont try to work on a KTP in a hurry, and expect to get anywhere. Yes we still had the remote fed heads for the show, but a real clean beam and real power transfer to the fibers could take a couple of days and many trial lenses before you get it right. I had a 2:1, 3:1, and 10:1 collimators with me, none of them were even close.

    4. 100 u fiber is way TOOO SMALL

    5. get rid of the medical computer if you can !

    6 if you buy one, use the built in medical fiber launch if possible.

    7. a AL2O3 scattering disk is needed on the shutter you use to block the KTP.
    The normal beam actuator arm gets TOO hot if you dont do something with the heat.

    8. The unit I worked on had underpressure, overpressure, and FLOW sensors. 90 PSI water in the field at the show site from a fire hydrant (with local fire's permission, blessing, and help) is way too much.

    9. While I have not personally experienced this, a lamp failing takes out the rods and lamp cooling jacket

    10 have a pro who alredy works on laserscope teach you how to align it, otherwise you can fry the crystal easily enought, and keep the intracavity beam off the KTP heater module, or it WILL go out of loop and try to melt the KPT.

    11. Think twice about buying one of these unless you like really big galvo mirrors and expensive lamps. Lamps draw about 32 amps.


    And yes, we had two fiber fed heads for the show at the 8 hour point. Collimation of thise laser is very, very, very, very hard in a hurry.

    Steve Roberts

  2. #2
    Join Date
    Nov 2007
    Bend Oregon USA



    28 watts???what was wrong with that POS mine do 50 W no blemo.

    FYI... a focused 50 watts qs beam goes thru a razor blade in .5 sec.

    400 micron is good for one beam or divide main beam into four beams and go with 200 micron fibers.

    always use an intra cavity shutter. or a fire brick with a hole drilled in the center.

    not familiar with a 720 but the z fold optical relay cavity emits almost zero IR down the beam path. (if set up correctly)

    It was good talking to you about this laser and pending show, sounds like you had a great time, I was selling kayaks in Port Townsend Wa. all last saw a gray whale!

    post pics of burnt need of a good laugh (just kidding of course)

    pat b

  3. #3
    Join Date
    Jul 2005
    Lancashire UK


    Steve ...

    that was a great bit of info .....

    im not one for reading books .... unless its a service manual etc ...

    but that story kept me on the edge of my seat .... infact i read it 3 times as i enjoyed it so much .....

    i wish more threads were of experiences like that ..... ok im a bit of a "techno sad" but .... when someone discribes that sort of info " as it happens " and you can picture it in your mind, and start to imagine you are there..... thats a great bit of communication

    all the best buddy .....

    thanks .... Karl

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