A second round of testing on the all-metal 3IFO QUAD unit Q7 is attached. After we saw a few cross coupling terms and struggled with coherence in the prior measurement set, we made a few adjustments to the QUAD mechanics. However, readjusting the lacing cabling and retuning the sensor mounting tablecloth seemed to not help much. There is still L and R bleeding into P on the reaction chain. We were able to improve the coherence by building a fort around the test stand however. The main chain looks to be in pretty good shape though.
The first attachement below is of Q7 with damping on and off.
The attachment below is of the Q7 (pink traces) undamped TFs compared to the 3IFO Q6 and Q8 units.
Screenshots of damping filters for DC offset diagnosis.
Spectra for all stages of Q7 attached. Note that the L1 and L2 stage OSEMs are not aligned and centered.