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VIS (PRM)
fabian.arellano - 12:15 Wednesday 06 November 2019 (11377) Print this report
Comment to Incorrect orientation of PRM in MISALIGNED state. (11236)

From seeing the picture I posted Kokeyama-san pointed out that the beam was not going into the beam dump, therefore, I changed again the orientation of the mirror.

  • With respecto to the previous position the beam clearly moved to the right of the view shown in the picture and the intensity decreased in an obvious way.
  • With the current offset value of the IM yaw actuation (-7000 counts) the IM is close to the limit of it's free moving range. When using -8000 counts it was definitively touching. I checked this by injecting a sinusoidal signal 100 counts in amplitude and 100 mHz ans checking the IM was following.
  • I had to apply actuation in BF yaw, pretty much what we had before: 15,000 counts.
  • There seem to be stray light which is not reaching the beam dump.
  • I didn't move the optic all the way to the other side to see the beam emerging at the other side of the dump, that would require a very large actuation in BF yaw.
  • I updated the snapshot.
  • The acompanying picture was produced with 1e6 units of exposure.

The amount of actuation used was

  • BF yaw test: 15,000 cnt,
  • IM yaw test: -7000 counts, (the limit is before -8000 counts)
  • IM pitch test: -4,500 cnt,
  • IM OL DAMP pitch: 4745 cnt (varies slighty each time MISALIGNED state is requested).
  • IM OL DAMP yaw: 106 cnt (varies slighty each time MISALIGNED state is requested).
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