The attached plots show the frequency noise seen by the reference cavity (green), the IMC (red), the REFL port (blue) and the POP port (brown). The first plot also shows the estimated in-loop suppressed noise in a lighter color as well.
The second plot shows uncalibrated traces but with a 30 kHz bandwidth. The peaks at ~7250 Hz and at ~13.6 kHz are already present in the IMC spectra when the interferometer is unlocked, and, therefore, are not introduced by the REFL servo. The I' channels are the DAQ sensor channels closest to true in-phase signals.
A few notes to the calibrations: