It seems like shifting the pole from 120Hz to 1.2Hz (alog 21300) reduced the beam jitter greatly only at 60 and 180 Hz. The broad jitter noise floor might have been somewhat reduced between 10 and 100Hz, but I see no change at 300Hz. In the attached, references are before, current traces are after.

Robert reported that the coupling to the chiller water flow dominates the periscope motion at around 300Hz (alog 21273).