[Keiko, Chiaki, Terri]

Because of the pitch yaw coupling seen at the TMSX table, the TMSY table QPDs were used to check if the same exists there. The ITMY and ETMY mirrors were shook in pitch and yaw at 0.1Hz with an amplitude of 1 and a gain of 0.1 using awggui (channel name K1:VIS-ITMY_TM_SET_P_EXC for ITMY pitch, etc). A PSD of the QPDs was taken on diaggui (channel name K1:TMS-Y_IR_QPDA1_PIT_OUT_DQ for QPD1 pitch, etc) with a bandwidth of 0.02Hz. The Area/RMS area was taken from 0.0600469 Hz to 0.199972 Hz to be around the peak (by eye) and normalised by the amplitude*gain. The data is summarised in the table below in counts/Hz. In the diaggui graph, a small peak could be seen around 0.1Hz, and pitch yaw coupling looks present. However, the table below shows the SNR is quite high so not much information can be taken from this right now.

The beam was off centre, in yaw especially. This means there is not a lot of inforamtion from shaking in yaw as it was not seen across the whole QPD. On Thursday the TMSY QPDs were installed and centred. Today the initial alignment procedure was performed after the vacuum leak checks and now the beam was very off centre (see attached). The amount the centring changes after alignment will be monitored this week to see if PZTs should be installed.

Different gains were used to see if the values can be compared once normalised (for ETMY YAW), but this was not the case. This could be due to the fact the beam was not centred on the QPDs. The effect of the centring on the values in the table will be investigated further to see if this is the cause. Using too high a gain can also cause the beam to go off the QPD so a value needs to be chosen to provide sufficient SNR but also keep the beam on the QPD.