Yesterday (August 7th 2017) , in order to get references, we tried to lock the cavity. However, it was impossible to control some of the mirrors due to saturation of the correction signal.
Last lock was effected the previous monday ( July 31st 2017 ).
There were some earthquake in the mean time ( August 3d, 4th 2017) which we suspect removed one magnet from the PR suspended mirror at least ( if we excite one of the coil of this mirror there is no change in error signal from local control, 3 others coil shows some changes )
We also had some trouble with the BS suspended mirror but it seems to be due to an offset (-0.2 on yaw, 4.1 on pitch). Once removed, the results were coherent.
Down are listed the results of some of the test we did to chack the saturation problem :
| open-loop (YAW;PITCH) | correction with open-loop offset value (YAW;PITCH) | max/min values for saturating the correction | |
| PR | 0.242 ; -2.6 | 0 +/- 0.1 ; 0 +/- 1.5 | 2.945/-5 ; -1.2/3.9 (high correction values before + every changes saturates (peak) ) |
| BS | -0.44 ; 0.54 | 0+/- 0.1 ; 0 +/- 0.5 | 1.72/-2.52 ; 1.065/-0.835 |
| IM | -0.356 ; 0.145 | 0 +/- 0.01 ; 0+/- 0.2 | ok/ok ; ok/-1.14 |
| EM | 0.55 ; 3.04 | 0.27 +/-0.1 ; 2.1 +/-0.1 | ok/ok ; ok/ok |
It also seems that the EM has some trouble ( pitch correction with open-loop offset is really different from 0 )
For both IM and EM there was "PSD tilt angle = -0.04 "