### Abstract
I implemented the WFS-PZT control state (ASC_RFON) in IMC guardian so that when the IMC lock goes down for some reason, the control in the PZT would turn off properly and the IMC lock would be restored and then the WFS-PZT control turn on.
After the implementation, I try to implement the DCQPD-IMC mirrors control state but when I tried to put the control of the DCQPD-MCO only in the PIT direction manually, the MCO PIT oscillation became noisy enough to be seen by the OPLEV signal, so I stopped implementing it today.
I checked the spectra and found that the IMMT1 TRANS QPD signal was noisier at lower frequencies than last December, and from the appearance of the signal, it seems that the air turbulence noise is mixing in. In other words, the ducts from the IMC chamber to the IMM chamber are not well sealed. I will try to seal the duct tightly and do the same measurement again.
### What I did
- From the RMS of the feedback signal (K1:IMC-DOF4_{P, Y}_OUT) of the WFS-IP2 control (±10V), a limit of ±20V was applied at the K1:IMC-DOF4_{P, Y}_LIMIT. As a result, the voltage higher than ±20V can not be applied to the PZT even if IMC goes down. While applying the PZT control, I intentionally tripped the IMC lock manually and confirmed that the IMC lock was restored.
- I implemented this behavior into the ASC_RFON state in the IMC guardian. I made sure that even if the IMC went down, the Guardian was working properly, locking the IMC and putting in PZT control.
- After the implementation, I try to implement the DCQPD-IMC mirrors control state. First of all, I manually checked if the control of the DCQPD-IMC mirror was properly turned on. The control to the MCE PIT was turned on and MCE PIT motion is not changed, but when the control to the MCO and MCI PIT were turned on, the motion of the MCI and MCO PIT became large from OPLEV signals. (fig.1)
- Checking the spectra of the TRANS QPDs, I found that compared to last December, the IMMT1 TRANS QPD signals have become noisier in the band below 10 Hz, and the motion of the mirror is not visible. (fig.2, 3)
Looking at the shape of the noise, it seems that the noise is caused by air turbulence. I thought that the aluminum foil duct from the IMC chamber to the IMM chamber was not so tightly sealed as it was in December last year. So I will try to seal the duct tightly and do the same measurement again.
