[ARAI, MIDOOKA, ELEONORA]

In order to calibrate the BS Oplev Length we compared two trasfer functions:

1) The one measured by Shoda-san  (/kagra/Dropbox/Personal/Shoda/BS/1800414/ BS_TF_TML180517.xml) obtained by driving TM length and looking at the uncalibrated response of the TM Oplev length (both in vertical and horizonal QPD output (named pitch and yaw)). Blue line in the attached plot.

2) The one measured by Izumi-san (entry 4799) obtained by driving TM length and locking at the MICH signal (count (driving) -> micron)

Dividing the second TF by the first one we cound obtain the calibration factor from count to mirror longitudinal displacement: 500 [micron/count]

Due to the complicate geometry of the BS oplev we expected to see some signal both in the pitch and yaw of the length QPD. According to Shoda measurement, the signal in yaw is about a factor 7 higher than in pitch, so we decided to take this one as lenght signal to calibrate.

Not that the factor 7 between vertical and horizontal response is not in agreement with Mark's calculations:  in fact according to what reported here the rotation of the axis induced by the geometry of the beam path should be about 62 deg and therefore the amount of signal seen in verical and horozonal should be more similar.