Polygonal mirror reflection beam Problem

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Discussion Overview

The discussion revolves around the challenges of achieving proper alignment in a handmade polygonal mirror setup for a spindle motor from an HDD. Participants explore methods to improve the alignment of the mirrors to ensure that the reflected laser beam produces a single line instead of multiple overlapping lines.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant describes the issue of misalignment in their handmade polygonal mirror setup, resulting in multiple laser lines instead of one.
  • Another participant suggests using salvaged polygonal mirrors from barcode scanners and proposes creating a jig to ensure precise alignment during the mirror setting process.
  • A different approach is proposed, involving making the facets adjustable using set screws and springs to allow for fine-tuning of the mirror angles.

Areas of Agreement / Disagreement

Participants present multiple competing views on how to address the alignment issue, with no consensus reached on a single solution.

Contextual Notes

The discussion includes assumptions about the feasibility of creating precise setups and the limitations of hand-made versus professionally made mirrors, but these aspects remain unresolved.

Who May Find This Useful

Individuals interested in DIY optical setups, laser applications, or those facing similar alignment challenges in mirror systems may find this discussion relevant.

anita1984
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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,
 
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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.
 
anita1984 said:
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,

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).
 
Thank you for the ideas , i will try them soon ,
Have a nice day
 

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