Improvements in Accelerometer Calibration Using Fringe Counting and Minimum Point Methods
Beverly F. Payne, Kari K. Harper
Improvements in shaker and interferometer design at NIST have provided more reliable calibration of accelerometers by laser interferometry. A dual-coil shaker provides excitation with low distortion and low cross-axis motion. Calibrations are performed by fringe counting a frequencies from 50Hz to 1kHz and by the minimum-point method at frequencies from 1kHz to 5kHz. The interferometer design described in this paper provides for easier alignment because a small retroreflector is mounted on the shaker table instead of a flat mirror. The small glass retroreflector is securely mounted in a stiff, titanium holder to ensure uniaxial motion at high frequencies. This system requires measurements to be made at only one reflection point on the shaker table. Normally data is obtained at three points on the shaker table for interferometers with a flat reflecting mirror. Calibrations using this system show excellent agreement at the upper frequencies with calibrations obtained using the freinge-disappearance method that was developed at NIST using piezoelectric shakers for the excitation. Comparison results are presented using the fringe-counting, minimum-point, and fringe-disappearance methods.
Proceedings of the 74th Symposium, Shock and Vibration Symposium