The excess of high frequency noise measured last summer when the cavity is locked (see entry #903) seems disapeared. This is good but the reason is not clear to me.

Note that in order to sum the line into the PZT  for the calobration we have reconnected the ramp potentiometer which was disconnected last summer,  following Pierre's advice,  in order to reduce the rampeato noise (see entry #875).

We have left it connected for now. It would be interesting to compare the difference in the error signal spectrum when it is connect and disconnected as done last summer (entry #883).