[Stefan, Shimoda, Nakano]

We measured some open loop gains. One is the FSS OLG and the other is the IMC-FSS combined system OLG.

The servo gains are as below
FSS: common gain= 0.5dB, fast gain = 17.2dB, slow servo gain = -9.0, function generator output signal amplitude = 10dBm, SR560 gain in PZT loop = 10
IMC: IN1GAIN = -16dB, common comp filter was on, slow boost filter was on

The measured signal are
A.the transfer function  from common OUT2 to common OUT1 of the TTFSS with excitation channel of common EXC
B.the transfer function  from A OUT2 to A OUT1 of the common mode servo with excitation channel of A EXC

A corresponds to FSS OLG and B corresponds to Gfss*Gimc/(1+Gfss)  (after my calculation, possibly it would be wrong) where Gfss and Gimc is the OLG of each loop. The attached figures are the plot of A and B. The third figure is the estimated G2 (B*(1+A)/A). There is strange peak at 40kHz in second and third figure. I have other consern, so I would report tomorrow after some investigation.