Extended Data Fig. 1: Quadrant photodiode calibration.
From: Measurement of gravitational coupling between millimetre-sized masses
The video-tracked yaw angle of the torsion pendulum is compared to the QPD readout (horizontal difference signal normalized by the total sum signal to reduce laser intensity noise coupling). A third-order polynomial fit to these data provides our QPD signal calibration. The occurrence probability accumulated over all our data runs shows the region in which a calibration is required, that is, Vx/Vsum ∈ [−0.4, 0.2].
