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Polygonal mirror reflection beam Problem

  1. Nov 5, 2009 #1
    Hello forum , i have a spindle motor from an HDD and i pasted to this motor 6 facets polygonal mirror, the problem is that the mirrors are not 100% alignment ( it's hand made) and the laser reflected from this mirrors is doing 6 lines ( where it should be one line if all mirrors are good alignment, all 6 lines should be overlap and we can see one line), what do you recommand me a tric to do it to make lines overlap , or a nice method to make another polygonal more profesional.
    every facet has a dimension of 3.5cmx1.9cm
    Thank you in advance,
  2. jcsd
  3. Nov 5, 2009 #2
    Here are some thoughts.

    The very precisely made polygonal mirrors are salvaged from barcode scanners and available from electronic salvage suppliers.

    A jig can be made to resemble a faceting machine (google for a pic).
    You would start out with a reasonably true polygon and mount it on a rod parallel to a flat.
    Then use a protractor to rotate it precisely.
    With a stop to set the height above the flat, you would lower the polygon onto a precut mirror with a drop of epoxy on top at each angle of rotation.
    This sets your mirrors at precise angles and parallel to the axis of rotation.
    Because distance will amplify inaccuracy, the more precisely you set up your indexing and parallelism the better the result will be.
  4. Nov 6, 2009 #3


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    Staff: Mentor

    Another alternative would be to make the facets adjustable, with a couple set scrrews and springs or something. If you aren't able to precisely machine the base part (which would take a pretty good CNC mill, I would think), then make one that has a way to adjust the 2-D tilt of each mirror (or at least all but one of the mirrors).
  5. Nov 8, 2009 #4
    Thank you for the ideas , i will try them soon ,
    Have a nice day
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