Fig. 3

Measured shape deviations of spherical concave mirror with radius R = 203.2 mm based on a) calibration assuming a plane display surface and b) using a polynomial display model of 7th order whose coefficients are determined during calibration. Both calibrations and shape evaluations were performed on the same phase measurement data. Measured shape deviation is reduced from PV = 33.40 μm, RMS = 8.23 μm in a) to PV = 1.98 μm, RMS = 0.46 μm in b) by application of the polynomial display model