Participants : Yuefan, Yuhang

When we tried to recover the FC lock, we had to act quite a lot on the BS control.

The pitch was saturating below -0.7 so we had to play with BS and IM yaw in order to reduce the saturation on the BS control while keeping a good beam position.

[ When the IM is misaligned it is really difficult to see the green transmitted beam because of another beam splitter has been installed on the green path in the squeezed bench]

We could finally performed a losses measurement still using the lock/unlock technique which gives us : 60.4 ppm +/- 7.3

With 2.54% misalignment and 0.25% mode-mismatching.

We also plotted the SHG stability over 1 000 s ("shgstability.png")

It seems to be quite stable around 1.5V even though some low frequency variations can be seen.

The last part from around 750s corresponds to the time we started to try to lock the FC.

It seems that some of the light came back towards the SHG.