Marc, Yuhang

Yesterday we spent some time to tweak a program made by Julia Casanueva for Virgo automatic alignment and adapt it to our case.

Then, we tried to measure the sensing matrix.

However, the green beam was not anymore centered on the QPDs..

We found out that the last steering mirror before the QPDs board was not well fixed. We fixed it back but we could not recover the alignment by acting only on this mirror.

It could mean that another mirror on the green reflection of the FC has been misaligned but we couldn't find which one so we acted on the both galvos to recenter the beam on the QPDs.

We measured the sensing matrix by injecting a 2Hz line on Input and End mirror pitch (300 amplitude) and yaw (200 amplitude) and extracted a driving matrix and phases to get all signal on I quadrature.

Today, we saw that the phases are tuned at the level of each segment so we will have to tweak a bit more the program as it gives the optimal phases at the level of pitch and yaw (not individual segment).

Anyway, today we tuned each segment phase 'by hand' to get all signal on I quadrature by either looking at the 11 Hz resonance of pitch or injecting a 2 Hz line. During this measurement the misalignment of the FC affected the accuracy of the measurement so we had to realign it, but also there were moment with large changes of the optimal phases...

The new phases are :