Participiant: Enomoto, Eleonora and Yuhang

The week before last week we found the problem of high voltage driver, and this is also the reason why we found there is a low pass filter inside our high voltage driver. So we decided to use it in a proper way, which means switch off the sensor-in switch. However, we found the lock of SHG becomes unstable after did that. So we did the characterization of open loop transfer function again.

We found the unity gain frequency of previous set-up is 795Hz while the phase margin is 89 degree which is fine.

However, the unity gain frequency of revised set-up is 376Hz while the phase margin is 66 degree which is worse. Besides, there is also a peak going above 20k Hz and brings oscillation.

Since Pier is developing servo in APC and we also want to use high voltage driver in a proper way, so we need to measure a list of open-loop-transfer-function again with the correct set-up of high voltage driver.

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Participaint: Eleonora and Yuhang

Besides, the remote control of 290m targrt is recovered based on yuefan's elog. However, its control requires the change of IP address and netmask. For the convience of remote control, we kept that computer inside our clean booth and we used another ether cable to achieve remote control.