Tunable mechanical monolithic sensor with interferometric readout for low frequency seismic noise measurement

This paper describes a mechanical horizontal monolithic sensor developed at the University of Salerno. The instrument is basically a monolithic tunable folded pendulum, shaped with precision machining and electric-discharge-machining, that can be used both as seismometer and, in a force-feedback configuration, as accelerometer. It is a very compact instrument, very sensitive in the low-frequency band, with a very good immunity to environmental noises, with tunable resonance frequency and integrated laser optical readout.