Monday 24th of April:
First we had a look at the diffused light on SPRB with the ITF at dark fringe, one can see some scattered points on MMT_M3 mirror (see picture 1, taken trhough the IR viewfinder)). Reflections from the 2 quadrants are also well visible (hiiting the back of B4_PD1 photodiode for one quadrant, see picture 2, and "dumped" on white cable for the other one).
Some light can also be seen on the tube between PR and the minitower (see picture 3), it is hard to know if this is some clipping of the main beam.
We started preparing the suspension of the bench. First we centered all LVDT that were accessible, the horizontal back right (BR) and front right (FR) were not centered as they are very difficult to acces.
The BR vertical was also not centered as it was already quite close to zero (around 400 um)
Then the bench was released after various tuning (weight adjustement, cable rearrangement, etc...) by Joris.
Then the bench was released after various tuning (weight adjustement, cable rearrangement, etc...) by Joris.
Once released we perform the balancing of the bench by adjusting the weight positions on the bench.
We also had to reroute some of the cables that were preventing the bench to float freely.
We left the bench and mSas suspension in that state for the night.
Tuesday 25th of April :
We left the bench and mSas suspension in that state for the night.
Tuesday 25th of April :
After more tuning of the mSas, we put the bench under vacuum and realised there was a leak.
After venting the bench and the interventiion of Antonio to fix the leak we pumped down the mini-tower again with success (see dedicated and more detailled entry 37360).
At this point the bench was stuck, so we used the steppo-motors to unstuck it and put it roughly were it should be using the set-points of the bench before vacuum.
Then with the remote help of Michal, we could control the angular degrees of freedom of the bench after identifying the actuators correctly (correction were not sent to the right LVDT).
Then with the remote help of Michal, we could control the angular degrees of freedom of the bench after identifying the actuators correctly (correction were not sent to the right LVDT).
Finally the bench position was adjusted (using again the steppo-motors ) and the angular set-points of the bench were finely adjust to recover the power on the B4_PD1_DC photodiode.
Franco was then able to lock the ITF in the recombined state with SSFS (see figure 1)
Franco was then able to lock the ITF in the recombined state with SSFS (see figure 1)
Joris will try to close the position loop of the bench (he has some fine tunig to do on the mSas supension).
Then the angular set-points will be adjusted tomorrow morning. The beam position on B4_Cam1 has to be adjusted using pico-motors so that it is centered.
Then the angular set-points will be adjusted tomorrow morning. The beam position on B4_Cam1 has to be adjusted using pico-motors so that it is centered.
