Naoki, Vicky
We successfully implemented the beam spot control with green QPD at FC trans by feeding back to ZM3 (Fig.1). The middle two are the green QPD P/Y signals and the bottom two are the error signals of the beam spot control P/Y. The cursors show the optimal green QPD offset for FC2 center which is decided in alog69338. After engaging the control, the green QPD signals settle to the optimal offset and the error signals become 0. The time scale of this control is ~1 min.
Fig. 2 shows the medm of FC ASC and Fig. 3-6 show the input/output matrix of FC ASC.
For stable FC green and IR lock with the beam spot control, we needed to clear history of filter bank of the beam spot control when the FC loses lock. Vicky added the clear history in down state of SQZ_FC guardian. The FDS with the beam spot control can be operated well by guardian.
The attached figure shows the last 28 hours trend. The beam spot control works well when FC is working. I walked the green QPD offset by centering the FC2 when the beam spot control is engaged. The updated QPD offset is 0.07 for pitch and -0.0037 for yaw (yaw is not changed).
