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Thread: Spectra Physics Beamlok 2060 Ar-ion

  1. #1

    Default Spectra Physics Beamlok 2060 Ar-ion

    Hi guys,

    I have a Beamlok 2060 Argon system. The laser is fitted with a prism for single line operation. The laser should deliver 3.5W @ 514.5nm (spec sheet)

    When I got the laser it had an Etalon which I removed since I do not need it for my application. Once I removed the Etalon the power dropped from 1.2W to 0.7W @ 514nm.

    I have tried aligning the rear mirror for optimum power however I could not achieve higher power.

    A friend of mine has told me that it is worth re-aligning the front mirror as well.
    I have done this before with an Innova 90 system however I cant work out how you can control the horizontal axis for front mirror plate. (For vertical the is a plastic knob)

    Does anyone know how I can find out where the knob is?
    Is it possible that the front mirror plate moves only in the vertical axis?

    Cheers,
    Mike

  2. #2
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    You have the beamlok box running correct? You know that the beamlok pickoff sensor sensor, in front of the OC, must be aligned as well as the cavity, correct? You know that the beamlok rear mirror is part of a deliberately unstable cavity and you probably do NOT have to move the front mirror, which does have both vertical and horizontal controls when you remove the front panel which is held in by magnets.

    I highly suggest you write down your head serial, psu serial, and beamlok driver serial and call SP-NEWPORT, speak to a service engineer, and get a manual in PDF or paper. Because of beamlok, this is a actively corrected cavity and is NOT anything like the coherent when you tune the cavity.

    The rear mirror has a convex, NOT concave, NOT flat, curve, and this means beamlok must be on if you want to see any stability. It has just enough designed in optical stability to stay lasing at 30-50% of rated power with beamlok off. Which is probably exactly what you are seeing. Beamlok moves the rear mirrors on piezo actuators in response to position changes on the quadrant position sensor mounted in front of the OC, there is a optical pickoff up there, and its position is adjusted by the three brass screws sticking out of the teflon block at the OC end. Removing the etalon knocked the optical path off enough that the feedback loop is not closing. The three brass screws are extremely touchy, and thus there is a pickoff alignment device included in the parts kit with the laser.

    It would take me 2-4 hours to tweek beamlok with a etalon and UV optics. Doing it in the visible takes about 4 hours the first time and 1-2 hours thereafter. Beamlok is a real witch to learn at first and the pickoff adjustments interact as they are NOT kinematic, but are three screws with springs.

    To remove beamlok you would still need to bias the piezos and change the rear mirror, if not the front mirror, too.

    You do have the remote with the XY display, right?, and are NOT using the serial port?


    And I'm curious, this laser is perhaps in Akron, Ohio??


    Steve
    Last edited by mixedgas; 06-22-2010 at 09:19.
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  3. #3

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    Hey,

    I do not know if the BeamLok box is running correctly because I do not know how I can check this....all I can do really to check if it is aligned is to center the target on the XY-display. Do you know how I can check it???

    I do have a manual and I am in contact with SP-Newport engineer who is guiding to do this but since it is the first time working with Beamlok systems it is more complicated that I thought.

    According to the drawings that I have, the front output coupler, is concave, and from what I read, the beamlok box controls the front output coupler. I dont know if I got is right....? At the rear end there is a prism with a flat high reflector..

    Finally a last question, the SP-Engineer told me that when removing the Etalon I should install a dummy part which comes originally with the laser. Unfortunately I do not have this dummy part, do you know if this could be the source of the reduced power problem???

    By the way according to the SP engineer my current and voltage levels are fine....

    thanks

    ps the laser is in London, England!

  4. #4
    mixedgas's Avatar
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    Do you have skype? The beam position sensor is up front. The piezo positioners are in the frame around the rear mirror. At least they were on the 2050 series I worked on.

    This is best done by voice.

    Here's the scoop. aligning beamlok for peak power is a iterative process. You walk the resonator for peak power, then walk the pickoff to center the beam, then turn on beamlok, see what happens, adjust the resonator again, adjust beamlok's sensor again, etc. The repeat the whole process. When you right on the money, the cross leds will be usually one led off dead center on both axis and it will be stable. You can then touch things up with the fine adjust screws on the rear plate.

    You actually have 4 adjustments on the rear plate, 2 adjustments on the front plate, and 3 screws that position the sensor. rear has x-y course, and x-y fine. Y (vertical) controls wavelength with the prism. The front has x and y. They are refered to as horizontal and vertical.

    The reason for the multiple passes is because beamlok will fight you until you have it centered on the sensor.

    The laser will live for a short period of time without the spacer, but yes you'll need one, or a piece of teflon cut to the same length and counterbored for the beam.

    Do you have the spare rear mirror mount as well as the prism? The spare all lines mirrors?

    Steve
    Last edited by mixedgas; 06-23-2010 at 19:06.
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  5. #5
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    followup:

    After several emails back and forth, and some annotated pictures. Mike is now a happy camper and has 4.5 watts cw all lines.

    Steve
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  6. #6

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    Many thanks to Steve for all guidance and assistance.

    Mike

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