We wrote a notebook found on Git/40m/measurements/LSC/FPMI/NoiseBudget/FPMISensitivity.ipynb for calculating the MICH, DARM (currently XARM), CARM (currently YARM) sensitivities in the FPMI lock which can be run daily.
The IN and OUT channels of each DOFs are measured at a certain GPS time and calibrated using the optical gains and actuation calibration measured in the previous post.
Attachment shows the results.
It seems like the UGFs for MICH and DARM (currently XARM) match the ones that were estimated previously (100Hz for MICH, 120Hz for DARM) except for CARM for which the UGF was estimated to be 250Hz and here seems to be > 1kHz.
Indeed one can also see that the picks in the CARM plot don't match that well. Calculation shows that at 250Hz OUT channel is 6 times more than the IN channel. Calibrations for CARM should be checked.
MICH sensitivity using REFL55 at high frequencies is not much better than what was measured with AS55.
DARM sensitivity at 10Hz is a factor of a few better than the single arm lock sensitivity.
Now it is time to do the budgeting.