Sheila, Kiwamu, Stefan, Alexa, Arnaud, keita.
Today we started out by projecting the spot on IM2 trans on the wall, and saw that it was so high that we were unable to steer it to the reference (from Oct 4th 2013) with our range (after the coil driver change). After some investigation, we set things back to what we thik the alignment was in late september, using both HEPI and using the BOSEM readbacks for the suspension alingments. After that we saw that the spot was still too high on the wall.
We then started measuring the beam centering using the A2L coupling of MC3. We used the A2L coupling to adjust the offset in the uncontrolled DOF (DOF4 pitch). We have reduced the coupling by a factor of 10.
As a result of the spot position adjustment on MC3, the IM1 trans light moved by this much:
This is a picture of the IM1 trans -- the camera itself is on IOT2L -- and the red sharpie mark at the center of the monitor was for the spot position recorded in this morning. So the beam spot went upward on the monitor i.e. the beam went down because the camera view is up side down. Interestingly, the beam shape improved and becoming more round-ish, indicating we are getting less clipped. Indeed, H1:IMC-TRANS went up from 800 to approximately 1100. Good.