The surface error is fairly constant in the central region, but rises sharply in the outer section. Figure 14 shows the rms as a function of radius.
The average, 0.5mm, is higher than the currently accepted value - it may reflect a calibration error in these images; or it may reflect the trend to higher rms as the holography resolution increases. (0.5 mm would suggest a Ruze degradation of 50 % at a wavelength of 7.5mm).
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