[Nakano, Miyazaki, Enomoto]

We did the same thing as was done before Phase1 (4831).
From this measurement, the best sideband frequency for f2 (in terms of AM sideband after IMC) was measured to be:
44.995 400(10) MHz,
which corresponds to FSR_IMC of 5.624425(1) MHz.

However, we are not so confident on this results since it is different from the frequency that we believed was optimized using X arm PDH signal by ~ 5kHz, though that optimazation we think was done in the precision of a few kHz.
If there is much AM at PSL, for example from MZM, this measurement can easily have systemtic error.
We will check if we can get good PDH signal of X arm with this frequency or not.