Wow! Contrary to all expectations - we managed to obtain a better wavefront for M2 than SAGEM did :) The interferogram below still contains some spherical aberration due to the daily temperature variations in the clean room, but this is easily removed by adjusting the null lens in piston.
The wavefront map shows some trefoil due to the mounting of the mirror, but nothing serious...
& with the interferometer's reference mirror tilted to produce enough fringes to allow good fits to the wavefront, we obtained a RMS of 0.048 waves (compared to SAGEM's 0.056 waves), a peak-to-valley of 0.28 waves (compared to SAGEM's 0.55 waves) & a Strehl Ratio of 0.91!
So - M2 is Not a problem at all! :)