Kokeyama, Ushiba
I was curious if the REFL WFSs responds to any mirror tilts in FPMI. Ushiba-san kindly shook ITMX and ETMX while the FPMI is locked, and the WFS responses were measured. The measurement data are stored in
/users/Commissioning/templates/diaggui/ASC/FPMI_ITMX_20220916.xml
/users/Commissioning/templates/diaggui/ASC/FPMI_ETMX_20220916.xml
From the data, here is the (partial) matrix in YAW in FPMI:
| WFS1_17_I | WFS1_45_I | WFS2_17_I | WFS2_45_I | ||
| ITMX | amp [cts area] | small | 420 | 230 | 520 |
| phase [deg] | 0 | 0 | 180 | ||
| ETMX | amp [cts area] | small | 390 | small | 500 |
| phase [deg] | 25 | -100 |
It is only a part of the matrix, but it looks good.
Possible next steps are:
- Check if this is repeatable (does it depend on the beam spot position on the ITMs?)
- Measure the responses to ITMY, ETMY, and BS
- Measure in the arm DOF basis
- Decide how to feedback and close the loop
