The main actions are briefly listed here:
- Paolo worked on the mirror driving matrix, the one that suffers of the absence of the UL magnet.
- Manuel reduced the corrections applied to the NI payload by using the
- Ettore worked on
> reducing to ~ 1% or below the sensing coupling pitch/yaw (needed for WI, ~10%)
> reducing the translation=>angle coupling due to PSD position mismatch WRT the lens focal planes (it was significant for WI, ~10%), now for both NI and WI is negligible (~ 1% or below)
> resetting to zero the setpoint for both WI and NI Mario (remind that the sensing noise is lower at the center due to hierarchical gain dynamics)
> resetting to zero the NI mirror angular sensing
We enjoyed the shift
In order to evaluate the eventual improvement of the angular control due to the intervention on sensing and driving, one can compare data regarding the lock of the arms before and after the activity. The first data collected in the evening were clearly affected by a new kind of instability, characterized by short spikes. Apparently the reason was a drift of PR from the correct parking position, pruducing resonaces of the arms with a sporious reflected beam. A few hours later an additional misalignment has been applied to PR and the effect has been removed, as shown by the trend of B7_DC_max and B8_DC_max.
