Gabriele, TVo

Summary: We turned on the ring heaters to test the ITMY HWS, it is the correct sign and about the right change in spherical power for the input wattage.  First we input 2 Watts but the results were faulty because of SR3 drifting, then we waited till SR3 was stable and turned the power up to 14 Watts and the results were more consistent with what we expect. The compiled the overall results are here:

Details: 

After we aligned HWS ITMY and felt we were close to the conjugate plane of the test mass, we started the HWS acquisition code and took new references.  In order to fine tune the alignment, we also turned on the ring heater at 2 Watts (1 on the bottom, 1 on the top) and looked at the spherical power as well as the prism_x and prism_y values. As shown by the animation, it looks very badly misaligned but we found that this was due to a drift in SR3 when we were taking measurements and this threw off our results. 

A few hours later we decided to energize the ring heater  with higher power (7 Watts on the bottom, 7 on the top) and made sure that SR3 was not drifting too much, we saw a ratio of the Prisms_X/Y and Spherical_Power drop to about 5mm. The animation below shows that the heating pattern is much more centralized on the heater, but this is with a bad reference prior to the SR3 drift mentioned above so it still has residual heating imbalance.  When we get a chance, we can try to get a good reference and redo this scan overnight.  Because the heating causes changes in alignment, it might not be compatible with other commissioning tasks (alignment, locking, etc)