http://www.pliniocamaiti.it/test_main.htm#C11

How 'bout them radial spokes. They are almost certainly caused by the
radial slots cut into the glass master-block that deforms the corrector
plate during polishing, presumably as the block approaches or exceeds
its usable life (the block wears as it is cleaned. This link is
obviously a severe case, whereas they are just hinted at in the
interferogram from baader. The two C11s I have owned certainly did not
look this bad, more in line with the quite decent .029 rms of the
German result.