To align the Aux. beam axis with SRC axis more precisely, we would like to use the flash transmitted from SRC. We estimated the flash power on AS PD when 1W Aux. input power was injected from the SR2 AR side. The power just after trasmitting SRM seems to be ~65 uW and this beam is transmitted to AS port via OSTM (T = 3%). Then, the estimated power on AS DC PD is ~2 uW. Therefore, it maybe too low to obtain the flash with AS PD.

So we put new DC PD (Thorlabs, PDA100A2) in OMC REFL path for monitoring the flash instead of AS PD. The channel for OMC REFL DC is already existed (maybe it was used previously but now it is not used.). So I connected the new DC PD to the channel (K1:OMC-REFL_DC). I confirmed the PD response with DGS.

However, the alignment work on POS table seems not to be completed (Maybe Saito-kun reported detail later). So I put the beam dumper in front of the PD and blocked the beam by the dumper for now.