Not logged in
Fri Dec 19 11:29:16 2008
MZ Trans PD
Lately, it seems that the matching of the input beam to the Mode Cleaner has changed. Also, it is drifting such that it has become necessary to continuously adjust the MC cavity alignment for it to lock properly.
Looking for causes we stopped on the Mach Zehnder. We found that the monitor channel:
which supposedly reads the voltage from some photodiode measuring the transmitted power from the Mach Zehnder, is totally unreliable and actually not related to any beam at all.
Blocking either the MZ input or output beam does not change the channel's readout. The reflection channel readout responds well, so it seems ok.