In order to test the configuration of the optical devices that will be used for the BS-OpLev in KAGRA, I simulated the basic setup of it on an optical table in the ATC.
For the position measurements, I have used a PSD (Position Sensing Detector) from Thorlabs (PDP90A).
The calibration of the PSD could be done in Y-direction only as the X-direction is not accessible due to the setup (for this I would need a 3-axis mount; the one used in the test was just a 2-axis mount). The resulting function Vy/Vsum is linear along the y-axis with a mean gradient of ca. 193 1/m (for comparison, the number that Eleonora has measured is 184 1/m for a PSD of the same type in TAMA).
A graph of the measured data along with a fit is shown in the attachment. Also shown are photos of the setup and a sketch of it.