Kuwahara, Fujisawa

We measured the calibration factors (dP/dθ, P is normalized output and θ is the tilt of mirror) of the optical levers at BS.
The method and the notations was according to those of XY end, http://klog.icrr.u-tokyo.ac.jp/osl/?r=939.
Note that in this measurement the chamber was open and the BS was not fixed for time savings, so the fluctuation of output was larger than those at XY end.

The matrix components were set as Fig.1, which was the same as that of Yend.
The calibration factors (dP/dx) from the displacement of beam spot (x) to normalized output signal (P) were measured, shown in the 1st row of the table below.
The length between QPD and mirror was L=1300(30) mm (1040(30) mm from mirror to chamber window by CAD + 260(10) mm from chamber window to QPD by ruler).
Then the calibration factor of the optical levers are obtained as dP/dθ=2L*dP/dx because of the simplest optical levers.

The results at BS Yaw(X), BS Pitch(Y) are respectively shown in Fig. 2, 3, and 

dP/dx:   -1.97(6) (out/sum)/mm,  2.29(3) (out/sum)/mm,  

dP/dθ:   -5.1(2)e3 (out/sum)/rad,  5.95(16)e3 (out/sum)/rad.