* Participants : Y. Aso, M. Eisenmann, M. Otsuka, S. Singh, K. Yamamoto, H. Wang

* Minutes :

• ITM polishing :

Nikon won 1st surface pre-post polishing

• PI update :

Optical Q simulation on-going found Q~10**12 instead of 10**9 in Kaihotsu thesis (likely 10**12 correct and typo for 10**9) How to consider HOM vs fundamental mode Q? OSCAR, Finesse, SIS useful simulation tools

• Birefringence at Mitaka

AlGaAs measurement vs angle of incidence on-going 2D measurement started and analysis on-going

• Birefringence at KAGRA (actually polarization sensor for DM search)

Installed s/p pol PD at TMS X/Y some presence of birefringence How to measure coating, ITM and ETM birefringence separately (maybe visible through change in Power or Temperature of the components?)

• Birefringence at Virgo

Contact by Flavio about possibility that Virgo mysterious noise is from birefringence Can BS coating induce differnt resonance condition for s and p polarization?