Fig. 4

Determined shape deviation of the display surface. Images a) to c) represent the full display surface (resolution: 2560 x 2048 pixels). Deviations in normal direction to the best-fit-plane are color-coded. Black areas were not accessed by the phase measurement. a Display shape from system calibration based on 25 phase measurements with the plane calibration mirror. Measured phase values near the display frame were masked out since these are prone to errors. Some regions near the corners were not accessed by phase measurements. PV of display shape deviation over the calibrated area is 0.94 mm. The outline of the calibrated display surface is drawn as white frame in b) and c). b Display shape deviation for the observed surface area from an exemplary phase measurement of the plane calibration mirror, derived from determined display shape in a). PV of display shape deviations over the observed area is 0.32 mm. c) Display shape deviation for the observed surface area from phase measurement with the spherical concave sample as surface under test, derived from determined display shape in a). PV of display shape deviations over the observed area is 0.05 mm. The observed display surface areas in b) and c) correspond to the shape measurements of the surface under test in Figs. 2 and 3 respectively