Fig. 3: Calibration experiment on the optomechanical MEMS geophone.
From: An optomechanical MEMS geophone with a 2.5 ng/Hz1/2 noise floor for oil/gas exploration
a Diagram of the optical readout method used to characterize the performance of the optomechanical geophone. A balanced difference method is used, which consists of a reference path and a sensing path, and two VOAs are used to adjust the optical power of the two paths. The sensing core is mounted on a PZT shaker. b Gravity field calibration based on a 6-axis hexapod; the sensitive axis is installed perpendicular to the table surface, and the displacement generated by gravity varies according to gcosθ. c Time-domain data of gravity step calibration, with the tilting range set from 0 to 8 degrees and a step of 0.2 degrees. d Fitting of the gravity step calibration data showing that the scale factor is 146 V/g with a nonlinearity of 1%
