Simon

The last measurements on the polarization maps for ETMY test-mass have been finished (with linear polarized input beam).
The results are attached as figures below, showing the maps with each 30 degrees and 60 degrees input polarization angle (0 degree is pure P-polarization -> horizontal with respect to optical table).

While in average there is a 5~6 degree offset for the 30 degree case, we have almost no offset in the 60 deg case. The reason is yet unknown. However, the already discussed prominent area in the upper-left region still shows ca. 10 deg offset with respect to the average, which is in agreement with all the other measurements.

In total, the polarization angle distributes in a range of ~20 deg over the entire map whereas the most important and serious changes happen within 10 deg.