We present a pair of seismometers capable of measurement in all six axes of rigid motion. The vacuum-compatible devices implement compact interferometric displacement sensors to surpass the sensitivity of typical electrical readout schemes. Together with the capability to subtract the sensitivity-limiting coupling of ground tilt into horizontal motion, our seismometers can widen the sensing band towards mHz frequencies. This has notable applications across a range of fields requiring access to low-frequency signals, such as seismology and climate research. We particularly highlight their potential application in gravitational-wave observatories (LIGO) in improving their observation capability of intermediate-mass black holes (∼1000M⊙). The sensors are based on a near-monolithic fused-silica design consisting of a fused-silica mass and fibre, showing improved stability and robustness to tilt drifts, alignment, and control compared to all-metal or mixed metal-silica designs. We demonstrate tilt sensitivity that surpasses the best commercial alternatives in a significantly reduced footprint compared to our previous iterations of these sensors.
@article{arxiv.2405.13475,
title = {Sensitivity and control of a 6-axis fused-silica seismometer},
author = {Jiri Smetana and Amit Singh Ubhi and Emilia Chick and Leonid Prokhorov and John Bryant and Artemiy Dmitriev and Alex Gill and Lari Koponen and Haixing Miao and Alan V. Cumming and Giles Hammond and Valery Frolov and Richard Mittleman and Peter Fritchel and Denis Martynov},
journal= {arXiv preprint arXiv:2405.13475},
year = {2025}
}