Alexa, Kiwamu ( a report from this past Friday)

We started checking out the REFL WFSs again. The misssion of the day is to engage the DC centering servos and check out the demod phases.

(REFL WFS DC centering servos)

We applied some modifications on the DC centering servo so that the servo basis REFL_A and REFL_B QPD signals. This had been adjusted to be some other basis (alog 9966), but we wanted a simpler basis. The attached is a screenshot of the new centering servo configuration. The input matrices are simple diagonal matrices so that the servo basis is simply REFL_A and REFL_B. In order to actuate on those basis through RM1 and RM2, we did some algebra based on the number reported in the previous alog (alog 9966). After the adjustment, we tuned up the gains to have a few second impulse repose time scale in every servo loop. Also, the sign of the output matrix were chosen such that all the servo gain consistently has negative sign.

(REFL_A_RF9 looked not great)

While we could easily re-adjust the demodulation phases on REFL_B_RF9, we could not perfectly adjut the demod phase on segment 1 of REFL_A_RF9. In addition, segment 4 of REFL_A_RF9 showed no reliable signals. This looked as if a cable was unplugged or something. Indeed the noise floor of segment 4 was lower than everyone else. We need to check REFL_A_RF9 at some point.

We did not check RF45 because we ran out the commissioning time.