J. Kissel

H1SUSRM1 and H1SUSRM2 damping loops have been upgraded to the so-called "Level 2" design (see G2200722 and LHO:60645).

Because Friday's aLOG conveyed some mild level of concern / a bold assertion that the difference seen between RM2 and all the other OMs, I gathered all RM1 and RM2 DOF's open loop gain transfer function with both the old and new configurations. A bazillion plots will be attached in the comments so it's more tractable to digest.

In short, without surprise given the proven success on the OMs, we improve all metrics: 
    - an immense amount more of sensor noise re-injection above ~5 Hz
    - a better, shorter ring-down time
    - increased on-resonance loop gain, while
    - still retaining > 30 [deg] phase margin on all upper and lower UGFs.
This of course comes a *some* cost -- there's more gain peaking near resonance, but it remains low Q, confined to regions only just outside the resonances, and no more than a factor of 2.5. The usual, completely reasonable compromise.

Note -- from the modeling efforts done during the design phase indicated that any HTTS (including the RMs) mirror displacement above ~5 Hz is dominated by *actuator* noise, not the BOSEM sensor noise re-injection -- even with the old filters. See pages 7, 13 and 19 of Last attachement to LHO:60698. So we don't yet expect to see an improvement in optic displacement with this new damping loop design. The benefit of these new filters (aside from the lower ringdown and on-resonance Q) will only be seen when we change their HAM-A drivers a la ECR T2100410.

New filters have been loaded and organized as is typical of my attack on damping loops for the level 2 design, leaving the old design still available for use if for some strange reason we still want to use them (I guess they'll be good to have around when we demonstrate the new filters performance after we upgrade the HAM-A drivers).