Annalisa mentioned that for some investigations of parametric instabilities and to understand better the arm cavity losses it would be interesting to have B1p_PD1 just after arriving to dark fringe.

Figure 1 shows a lock acquisition,  B1p_PD2 is alway open, and B1p_PD1 sees about 10 times more power, and is opened only at step 124. B1p_PD1 saturates at ~50mW, so it can't be kept open when the MICH offset is 0.1, but it could be open just after.

A simple improvement would be to put the B1p_PD1 opening when entering state 120, so when entering the LOCKED_PRITF_DF state. This would reduce the delay from 100s to 10s (some more complicated solution could be possible to reduce the delay by a few more seconds).

For the parametric instabiltiy B1p PD1 audio would need to be put back in the data with 1MHz sampling, but probably only in the raw_full data that are stored for a few days.