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fabian.arellano - 11:27 Friday 12 March 2021 (16247) Print this report
Comment to Test of PR3 mirror pitch stability using the Donald Trump method. (16239)

This is the calculation I didn't write yesterday because I was sleepy.

As reported, we monitored the change in pitch produced by the Trupm procedure with the oplev, but we can also use the OSEMs.

  • The values of the OSEMs before and after the Trupm procedure were
    • V2: 41 µm → 228 µm.
    • V3: -19 µm →  188 µm.
  • Because these OSEMs are sensitive to roll also, to calculate the change in their readouts related to pitch, we must consider the average before and after:
    • Before: 11 µm.
    • After: 208 µm.
    • Difference: S = 197 µm.
  • The distance from the OSEMs V2 and V3 to the suspension rod (see details in this diagram) is R = 48 mm.
  •  Then, the change in pitch ( S / R ) = 4.1 mrad. This number is consistent with what we measured when we glued the wire and disturbed the alignment (3.8 mrad, see this notebook page ) and also with the measurement carried yesterday morning from the control room (-3.9 mrad).
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