J. Kissel, T. Shaffer

I've finally gotten around to doing detailed processing of some of the new HAM Tip-Tilt Suspensions (HTTS), namely ZM1 and ZM2. 

ZM2 looks good, but not great -- the latest data set (from LHO aLOG 40254 back in January) shows hints of pitch cross-coupling into yaw -- but still totally acceptable for our intended use.

ZM1 -- that which had a magnet polarity saga (identified in LHO aLOG 40847, solved in LHO aLOG 40851), and was after afterword rubbing -- still is rubbing, even after an unalogged attempt to fix it, but identifying that the UR flag looks poorly seated. 

I attach a newly revamped set of individual measurement HTTS plots, i.e. that produced by 
    /ligo/svncommon/SusSVN/sus/trunk/HTTS/Common/MatlabTools/plotHTTS_dtttfs_M1.m   (rev 9163)
that correctly show the Euler Basis drive to OSEM sensor response plots.

The EUL2OSEM plots (pgs 7-9) in the individual results .pdfs reveal an interesting difference between a functional suspension (ZM2) and ZM1 -- namely that the UL frequency response is markedly different from the model and from ZM2. Where the model expects (and ZM2 shows) a zero from both the UL and UR sensors at 1.3 Hz (ZM2 shows 1.03 and 1.11 for UR and UL, and only slight different overall response shape), ZM1 shows a poorly coherent zero at 1 Hz in UR, no zero in UL, and again a markedly different response from UR.

Further corroborating evidence that ZM1's UL OSEM is problematic?
    - The individual OSEM sensor response to a simple, one-at-a-time, DC offset on the COILOUTF banks for ZM1, shows that UL exhibits less response than UR.
    - TJ says that the UL flag is poorly seated, and is thus coming in through the OSEM sensor / coil at an angle with respect to the nominal sensing / control axis.

I also attach the usual comparison against other suspensions, using a new revision of 
    /ligo/svncommon/SusSVN/sus/trunk/HTTS/Common/MatlabTools/plotallhtts_tfs_M1.m
which now plots the phase in addition to the magnitude allowing us to #RespectThePhase

This shows that ZM1's P resonances are slightly low in frequency, implying a heavier moment of inertia, and it's dreadfully obvious that the Y frequency is totally distorted into several peaks. The lower frequency at 1.17 Hz isn't even a cross-coupled L mode at 1.27 Hz. However, the upper-most frequency is indeed a cross-coupled pitch mode.

TJ will investigate further once the opportunity presents itself later this week.