Prototype of interferometric absolute motion sensor

Abstract

For many applications, there is an increasing demand for low cost, high resolution inertial sensors, which are capable of operating in harsh environments. Based on recent developments in optical seismometry, this paper presents a new small interferometric inertial sensor with a resolution of 3pm/Hz above 4Hz. Compared to most state-of-the-art devices, this prototype does not contain any coil, which offers several important advantages: (i) when it is used for active control, it magnifies the control performances around the sensor resonance; (ii) it decreases the thermal noise in the suspension (Brownian motion), (iii) it is compatible with magnetic environments (like particle collider); (iv) as the interference fringes sweep continuously across the detector, it allows a real time calibration of the parameters, and thus the calibration can be continuous monitored and updated.