An accelerometer system comprising: an optical beam source configured to generate an optical beam (O OA) having a predefined center frequency and which is frequency-modulated about the predefined center frequency; an optical cavity (16, 50)comprising: - a first mirror at a first end of an axial length of the optical cavity (16, 50, 162); - a second mirror at a second end of the axial length of the optical cavity (16, 50), the second mirror being movable along the axial length of the optical cavity (16, 50) in response to an external acceleration, the optical cavity (16, 50) being configured to receive the optical beam (O OA) and to emit a resonated optical beam (O DET); and - a plurality of electrostatic or electromagnetic force rebalance electrodes configured to apply a force to the second mirror in response to a change of the intensity of the resonated optical beam (O DET) corresponding to the external acceleration along the axial length of the optical cavity (16, 50), the magnitude of the force corresponding to the magnitude of the external acceleration, and an acceleration detection system configured to measure an intensity of the resonated optical beam (O DET) and to calculate a magnitude of the external acceleration along the axial length of the optical cavity (16, 50) based on the intensity of the resonated optical beam (O DET) resulting from motion of the second mirror; and a stabilization system configured to stabilize the predefined center frequency of the optical beam (O OA) independently of the external acceleration based on the frequency modulation signal of the optical beam (O OA). an optical beam source configured to generate an optical beam (O OA) having a predefined center frequency and which is frequency-modulated about the predefined center frequency; an optical cavity (16, 50)comprising: - a first mirror at a first end of an axial length of the optical cavity (16, 50, 162); - a second mirror at a second end of the axial length of the optical cavity (16, 50), the second mirror being movable along the axial length of the optical cavity (16, 50) in response to an external acceleration, the optical cavity (16, 50) being configured to receive the optical beam (O OA) and to emit a resonated optical beam (O DET); and - a plurality of electrostatic or electromagnetic force rebalance electrodes configured to apply a force to the second mirror in response to a change of the intensity of the resonated optical beam (O DET) corresponding to the external acceleration along the axial length of the optical cavity (16, 50), the magnitude of the force corresponding to the magnitude of the external acceleration, and - a first mirror at a first end of an axial length of the optical cavity (16, 50, 162); - a second mirror at a second end of the axial length of the optical cavity (16, 50), the second mirror being movable along the axial length of the optical cavity (16, 50) in response to an external acceleration, the optical cavity (16, 50) being configured to receive the optical beam (O OA) and to emit a resonated optical beam (O DET); and - a plurality of electrostatic or electromagnetic force rebalance electrodes configured to apply a force to the second mirror in response to a change of the intensity of the resonated optical beam (O DET) corresponding to the external acceleration along the axial length of the optical cavity (16, 50), the magnitude of the force corresponding to the magnitude of the external acceleration, and an acceleration detection system configured to measure an intensity of the resonated optical beam (O DET) and to calculate a magnitude of the external acceleration along the axial length of the optical cavity (16, 50) based on the intensity of the resonated optical beam (O DET) resulting from motion of the second mirror; and a stabilization system configured to stabilize the predefined center frequency of the optical beam (O OA) independently of the external acceleration based on the frequency modulation signal of the optical beam (O OA).