Katsuki, Marc

We measured the distance between the blade at z = 25 mm and the last steering mirror.

From this distance and knowing the 2.5deg angle of the beam we found that the beam is hitting this last steering mirror at y = 134.4 mm (in the frame of the translation stage).

We placed the blade at this position and z = 110 mm and tweaked the steering mirror to get half of the power transmitted.

After little back and forth, we measured the horizontal angle of incidence of 0.024 deg and the vertical one to be 0.015 deg.

Because this is more than 10 times smaller than KAGRA requirement on the C-axis angle wrt to the surface normal we can consider that we are now in normal incidence.

We realigned the imaging unit , did the polarization calibration and started the measurement with shinkosha 7 (new center at x = 398 mm and y = 162 mm).

However we are not sure if this substrate has a wedge or not which means that we might see the fringes that Manuel observed...