Polygonal mirror reflection beam Problem

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SUMMARY

The discussion focuses on the alignment issues of a handmade polygonal mirror assembly used with a spindle motor from an HDD. The user reports that the laser reflects six distinct lines instead of one due to misalignment of the mirrors, each measuring 3.5cm x 1.9cm. Recommendations include creating a jig resembling a faceting machine for precise mirror placement and considering adjustable facets using set screws and springs for fine-tuning alignment. The importance of precision in setup is emphasized to minimize distance-related inaccuracies.

PREREQUISITES
  • Understanding of optical alignment principles
  • Familiarity with basic machining techniques
  • Knowledge of epoxy application for mirror assembly
  • Experience with jig design and construction
NEXT STEPS
  • Research techniques for creating a faceting machine jig
  • Learn about adjustable mirror mounts and their design
  • Explore precision epoxy application methods for optical components
  • Investigate CNC machining capabilities for mirror fabrication
USEFUL FOR

This discussion is beneficial for hobbyists and engineers involved in optical systems, laser technology enthusiasts, and anyone interested in improving the precision of handmade optical components.

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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