Dan.Chen-san, Hirata-san, Ikeda

K-Log#28635
We investigated the cause of the 60 Hz noise.

We found that it occurs when the Picomotor AC adaptor is connected to the Picomotor Driver.
Perhaps the noise could be caused by the AC adaptor itself.

We will consider how to counteract this again.

Power supply configuration.
[table tap] - AC100V -> [rebooter] - AC adapter -> [Picomotor Driver].

What we tried.
1. measured the current noise.
=> Fig. 1
2. rewired AC100V from table tap to rebooter
=> no effect. 
3. unplugged the rebooter's AC100V.
=> effect. Fig.2; we think the AC in the Pico had an effect.
4. reconnected the rebooter and switched off the Picomotor Driver
=> no effect.
5. unplugged AC adapter from Picomotor Driver
=> effect.

Depending on what is this picomotor driver for, it might be ok just unplug it when requiring lower noise control of the interferometer.

We found an in-vac D-sub cable (5th pin) was disconnected. It was labeled "IM V2" at the in-air side feedthrough.

After fixing this pin, the 60 Hz noise on the LVDT V2 was reduced. (red: after fixing, blue: 1 hour before this work (during lunch time))