Examining optomechanical calibration error using intrinsic properties testing

Optomechanical accelerometers are championed by the National Institute of Standards and Technology (NIST) as a path to ubiquitous, embedded acceleration references [1,2]. Sensors employing a basic parallelogram geometry for the mechanical resonator are being considered for a variety of applications, including hybrid systems combining low frequency optomechanical accelerometers with atom interferometers to create absolute gravitational acceleration references [3]. Recent comparisons of the optomechanical scheme with ex situ acceleration calibration techniques revealed discrepancies [4] as in Figure 1. We believe such discrepancies call into question basic assumptions of the parallelogram design, in particular: sufficient alignment of the optical to the mechanical axis by manufacturing tolerances insignificant motion of the reference surface of the interferometer (launch fiber). negligible influence of higher vibrational modes to the mechanical transfer function at low frequency In this poster, we test the first two of these assumptions by attempting to measure the alignment of a sensors intrinsic coordinates with its physically defined reference surfaces [5]. If the rotation of intrinsic coordinates from reference surfaces is found to be small (i.e., off and cross axis sensitivities in physical coordinate space are found to be small), then errors in on-axis calibration, such as Figure 1, suggest a problem with the second assumption. Cervantes, F. G., et al, High sensitivity optomechanical reference accelerometer over 10 kHz. Phys. Lett.104, 221111 (2014) Feng Zhou, et al, "Broadband thermomechanically limited sensing with an optomechanical accelerometer," Optica 8, 350-356 (2021) Richardson, L.L., et al. Optomechanical resonator-enhanced atom interferometry. Commun Phys 3, 208 (2020). https://doi.org/10.1038/s42005-020-00473-4. Pratt, Jon R, et al, Verification of a self-calibrating optomechanical accelerometer for use as a strong ground motion seismic reference, Metrologia, http://iopscience.iop.org/article/10.1088/1681-7575/ac1402, 2021. Michael Gaitan et al 2021 Metrologia 58 035006