Aritomi and Yuhang

We measured the open-loop transfer functions of CC1 and CC2 yesterday.

We could see from these two figures that 0dB line cross 500Hz and 7kHz for CC1. While 0dB line cross 600Hz, 4kHz and 7kHz peaks at the same time for CC2.

These peaks make locking not easy to achieve. We are thinking about the following things to try:

• to dump resonance by putting rubber
• to use a notch filter to not excite the resonance
• to glue PZT and mirror on the phase shifter