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AOS (Optical Levers)

kouseki.miyo - 21:16 Thursday 01 February 2018 (4090)

Calibration of the Oplev for WAB cooling test in IYC

Akutsu, Hasegawa, Miyo

We calibrate the optical lever for WAB in IYC chamber.

Measurement data is plotted in attached image about both pitch and yaw.
Fitted red curve is a error function.
Green line is a slope where oplev beam is at the center of the QPD.
The conversion factor from beam position to digital counts is obtained from this green line coefficient.
Pitch is 2.2 count/mm.
Yaw is 2.0 count/mm.

Images attached to this report

Comments to this report:

kouseki.miyo - 21:14 Thursday 08 February 2018 (4147)

Roughly speaking, linear range is +/- w0/2 mm, where w0 is beam radius.
In case pitch, w0 = 0.29/2 = 0.15 mm.
In case yaw, w0 = 0.38/2 = 0.19 mm.

Therefore, linear range of pitch is about 2*0.15/2000 = 150 urad, yaw is 190 urad.