Introduction

  • Many space and large mirror optical applications require a light-weighted support design. 
  • Light-weighted optics that have been polished using conventional techniques, often show print-through, or quilting errors.
    • Conventional polishing techniques apply normal forces that can deform non-supported surface areas causing variation in polishing rate. 
  • Material removal from MRF is a result of shearing forces and very little normal force is applied to the surface of an optic; therefore, MRF does not cause any print-through or quilting. 
  • Due to its deterministic nature, MRF can also correct pre-existing print-through errors.

 

lightweightmirror lightweightmirror polish  

 

 

lightweightmirror polish conventionalmodel lightweightmirror polish mrfmodel lightweightmirror measure

 

   

 

 


 

Light-weighted structure on back of mirror

  • Light-weighted mirror
    • Size: 100 mm Φ
    • Material: Silicon Carbide
    • Surface form: Plano
  • The Goal
    • Correct figure error that is a result of print-through from conventional polishing
  • The Configuration
    • Q-flex 100
      • Raster Polishing
    • 150 mm wheel
      • Large spot to minimize cycle time
    • D10 fluid
      • Achieves best roughness on Silicon Carbide

 

 

 


 

  • 10x RMS improvement

    • Quilting/print-through corrected efficiently.
    • MRF does not induce print-through due to minimal normal force during polishing.

 

figurecorrectionresults lightweightedmirror    spot lightweightedmirror

xslices lightweightedmirror

 

 


 

 

  • MRF successfully improved the figure error to <8nm RMS
    • 10x RMS improvement

  • Low normal forces and relative insensitivity to small gap variations means MRF does not induce quilting/print-through artifacts.

  • High lateral resolution of MRF process is efficient at correcting quilting/print-through artifacts

 

 

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