Mirror "C" tested as 1/16th wavelength on the interferometer.

Using Dave Rowe's FringeXP program and this interferogram, here is the Test Report that resulted:

The RMS wavefront error and Strehl ratio are much better than I predicted. The Strehl ratio says that it is only 3.3% short of theoretical "perfect". The test bench is conservative; but useful.

The RMS surface error is less than 9nm. That is 333X smaller than the finest grit that I used (3 micrometers)! Amazing!