Kiwamu, Stefan,

Both ALS_DIFF and ALS_COMM were straight forward today, and we got them locked literally in minutes. I.e. the ESD is still working fine.

We misaligned the arms, and verified that 3f locking works just fine without the arms.

We locked the arms and parked them 1kHz off resonance. I this configuration the the RF27_I signal worked fine, but the REFL27_Q signal had significant contamination from the COMM noise at 70Hzish (periscope peak). Thus we designed a broad notch filter in the mich loop, which kept the BS from saturating.

However it seems that MICH is still too strongly contaminated by the low frequency COMM noise. As a result the MICH loop seems to drift out of its linear range.

Ideas:
 - divide REFL27_Q by POP_18 to expand the linear range
 - rephrase REFL27 to reduce the coupling

Either way, an earthquake told us to get some sleep.