Typical accelerometer calibrations by laser interferometer are performed by measuring displacement at three places on the shaker table. Each of these measurements made along the perimeter of the accelerometer require repositioning and realigning of the interferometer. This is done to approximate the actual displacement of the accelerometer. Using a dual coil shaker with a small moving element and two mounting tables allows placing the accelerometer on one table and measuring displacement directly on the center axis of the second table. This was found to work effectively at lower frequencies, up to about 5 kHz, with mounting tables of conventional materials such as stainless steel. However, for higher frequencies the use of steel results in unwanted relative motion between the two mounting tables. Mounting tables of beryllium with nicket coating have been used at NIST to overcome this difficulty. This paper will show the calibration results of single point, on axis measurements, using fringe counting and sine-approximation methods. The results compare favorably with three point measurements made by fringe disappearance using a conventional piezoelectric shaker at NIST at frequencies up to 15 kHz.
Proceedings of SPIE 7th International Conference on Vibration Measurements by Laser Techniques
June 19-23, 2006
7th International Conference on Vibration Measurements by Laser Techniques: Advances and Applications
accelerometer, calibration, interferometer, laser, metrology