ACCELEROMETER CALIBRATION BY DYNAMIC POSITION MEASUREMENT USING HETERODYNE LASER INTERFEROMETRY

A new approach to accelerometer calibration is presented which is applicable to frequencies from 1 mHz to above 25 kHz and to amplitudes from 1 nm to above 10 m. Heterodyne laser interferometry is used to measure dynamically the position of the vibrating accelerometer as a function of phase angle through the vibration cycle. Coherent integration is used to improve the length resolution and noise immunity, and a complete description of the vibration is obtained by Fourier analysis of the position measurements. Insensitivity to distortion is achieved by measuring the accelerometer voltage simultaneously in a similar manner and calculating the accelerometer sensitivity from the fundamental length and voltage amplitudes. One implementation of this approach is described and shown to be capable of calibrating accelerometers in the frequency range 5 Hz to 5 kHz with a least uncertainty in amplitude of ±0,01 nm.