We are trying to make sense of what we see during the CARM offset reduction. We believe that we are at a lower CARM offset than we estimated given our power build up.

When our power build up is ~120 (wrt single arm, as measured by the TR QPD - Sheila is checking the normalization), REFL_DC is already at ~50% of its max power, and it looks like REFL_9I is indeed already within its linear range. However, at that point we should already be close to ~500 x single arm power (or half of the total build up, nominally 1000 x single arm). POP_DC shows only a modest factor of 2.5 increase with respect to only sidebands in the recycling cavity, it should be higher than that. 

This would explain while we couldn't further increase the CARM offset, as the TR signals are becoming flat, and why we couldn't keep using the same AS WFS signal in loop, as it is changing sign at low CARM offset (  see Dan's model ).

We will try to figure out why this is happening (are we simply misaligned? low carrier recycling gain? loss in the arms?...).

The positive message is that there is no point in trying to further reduce the CARM offset in this state..so we are done with that.

Kiwamu posted  these simulation plots  as a comparison, and  LLO log 12765  is an example of the LLO sequence.