I looked at 1 hour of the input power / IMC power oscillations that occurred last weekend and how that power change effected the alignment of the IO IMs, IM1, IM2, IM3, and IM4.
4 attachments:
- PSL power in / IMC trans
- IM1-4 length: span of the y axis is 0.6urad on all plots - all IM optics show the oscillation in length, amplitude of the signal is largest in IM2
- IM1-4 pitch: span of the y axis is 0.45urad on all plots - IM2 clearly shows the oscillation while IM1, IM3, and IM4 do not - IM1 shows jumps in alignment up to 0.1urad - IM2 amplitude is ~0.25urad (p-p)
- IM1-4 yaw: span of the y axis is 0.6urad on all plots - IM2 clearly shows the oscillation while IM3 and IM4 do not - IM1 shows some oscillation but also jumps in the alignment - IM2 amplitude is ~0.25urad (p-p)
One explanation for the difference of IM2 compared to IM1, IM3, and IM4, is that the beam on IM2 is no longer centered, so the change in IMC power causes the optic to change alignment.
If this is true, the change of the beam centering on IM2 could be big enough to have significantly changed the alignment of the beam through the Input FI.
UPDATE: IM1 glitching
IM1 UR OSEM signal is glitching and the glitches can be seen in DAMP_P and DAMP_Y at about 0.1urad in both signals.
These glitches do not show up in IM4 Trans.
UPDATE: IM2 oscillations clearly seen on IM4 Trans:
| amplitude (p-p) | |
| IM4 trans pitch | 0.035 |
| IM2 pitch | 0.25urad |
| IM4 trans yaw | 0.015 |
| IM2 yaw | 0.25urad |
Plot attached shows IM4 trans pitch and IM2 damp_p in blue, IM4 trans yaw and IM2 damp_y in green.
