Process Steps

1. Subaperture Stitching Interferometry (SSI) is used to:

  • Monitor the improvement
  • Provide target maps for the MRF process
  • Evaluate the final figure and radius specification

SSI provides high precision measurement for MRF target maps and for final element verifications.
Calibration of transmission element ensures accurate pixel scale and error mapping.
Reference wave error is calculated and removed for each measurement.

2. Stress mirror polishing (SMP) of a Zerodur flat is used to:

  • Introduce the cylinder surface form

3. Magnetorheological Finishing (MRF) is used to:

  • Correct the residual error from the SMP
Zerodur sample prepared fo SMP
Zerodur sample prepared for SMP

MRF process

Cylinder is measured with SSI