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Thread: SP 127 HeNe - Cleaning & Adjustment

  1. #11
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    With your first arrangement, the mirrors would just be in a periscope arrangement with the lasers not mounted along the same line.

  2. #12
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    Yeah, so long as you still had a double-bounce (one for near field, one for far field), you could still make it work... But like you said, the tubes wouldn't be in the same line.

    Adam

  3. #13
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    Last time I did one of those from scratch it took me 4 hours just to get lasing and another hour to peak it using the side adjustments and main adjustments. The first hour was getting the alignment hene down the bore. That was with both lasers bolted on an optical table and two fold mirrors in the alignment beam. Two mirrors are used as that way you have a height adjustment. The resonator is somewhat sensitive to how you support it during alignment, the bore can flex considerably in some cases.
    ~
    The bore is small and you need a tight beam diameter on the alignment hene. These days to align stuff like that I have switched to a green hene with their usual very tight beam diameter and ultra low divergence. The Greene really helps.
    ~
    It can be done, but your alignment laser and the target laser must be bolted down. JEM, you have the skills for this, be patient.
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    Also don't tear or crack the Brewster window rubber boots, they are delicate. Go slow.
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    Last edited by mixedgas; 08-04-2017 at 09:40.
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  4. #14
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    Thanks for the advice Steve, very much appreciated
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  5. #15
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    I have never done this but would it make sense to line up a perfect reflection between the alignment laser and mirrors before placing the laser to align on the table. Then lower the tube into position and look for the point where it comes down the bore? At least you know you have a solid align to work with.

  6. #16
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    The mirrors give adjustability to the tilts of the alignment beam. Doing as you say would mean one would have to mount the laser to be aligned on an enormous tip-tilt mount. Everything gets easier if the mirrors used for alignment have micrometer drive handles with absolutely no slop, backlash, or crosstalk. Use your best mirror tilters!

  7. #17
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    As I said never done it before. Tweaked but never from scratch.

    I'd bet the factory has a jig that turns the screws to some known start point and then turns them each one at a time via servo while looking for a change in brightness of a reflection. Once the beam starts then it just turns to maximize the brightness. Auto align sort of.

  8. #18
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    Quote Originally Posted by kecked View Post
    As I said never done it before. Tweaked but never from scratch.

    I'd bet the factory has a jig that turns the screws to some known start point and then turns them each one at a time via servo while looking for a change in brightness of a reflection. Once the beam starts then it just turns to maximize the brightness. Auto align sort of.

    Yeah, their "autoalign" was likely a human with an autocollimater with a quadrant photodiode with analog readouts and a eye piece to view the autocollimation spots.

    If you do one or two a week it gets easy..

    Steve
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  9. #19
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    Steve MixedGas got my 127 (in an old Image Engineering full color, Air-cooled projector ) putting out like new ..years ago..
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