* TF measurement * 

I measured the TF of the mirror using the Oplev.
According to the measurement, the something like high pass filter is included in the OSEM sensors, since the TF measured by the Oplev fits to the normal pendulum TF very well.
Note that the Oplev signal is not calibrated yet.

I fitted the measured data.
Then, I found the OSEM sensors have the high pass filter with the 0.46Hz cut off 1 order high pass filter.

I cannot have found the reason yet.
Anyway I can compensate the filter now...

* Actuator Calibration *

I calibrated the actuator using the DC transfer function of the OSEMs.
The actuator gain is set so that the transfer functions are 1 at DC with OSEMs.
Then the values are:
L: 73.5
P: 118.34
Y: 187.79
I will calibrate them to the physical values later...

* Coil driver *

We found that the coil drivers do not work sometimes.
I found that this is because of the analog WD system.

Therefore, I have set the digital WD system more severely.
However, we have WD system only at the Oplev sensors. The current system cannot sense the Length satulation.
I am wondering if we should change it to OSEM sensors, make new WD ports for OSEMs, or just leave it...