We preform more FINESSE simulations on the AS72 scheme, focusing on how the signal changes when we switch to the new SRM (T_srm=0.37 -> 0.32), and possible solutions if we are sitting on the ill-conditioned regions. 

Conclusions:

1. If the AS72 sensing matrix measured now (with differential wavefront distortion; T_srm=0.37) behaves well, the sensing should be fine after we replace the SRM.

2. If the sensing matrix for AS72 is close to being degenerate, after replacing the SRM the sensing is likely to be even worse.

In case that the sensing matrix is bad (e.g. we are sitting at AS port gouy phase 45-75 deg in the plots), possible solutions:

    i. Increase the SRC one-way gouy phase to ~20 deg (e.g. with SR3 ring heater; current nominal SRC gouy phase is ~18 deg). This should be the BEST solution. For more details, please see 37222.

    ii. Use ASA_72Q and ASB_36Q for SRM/BS sensing. This scheme work only for a very narrow (AS port gouy phase + diff lens) space. 

    iii. Use ASA_72Q and (ASA_72I - ff x ASA_DCQPD) where the ff is set to decouple the spot centering. This should cover the AS port gouy phase space corresponding to 45-70 deg in the plots.