Vibration calibration at high frequencies

Important results from the project

The project has demonstrated that the concept of modifying a commercial laser Doppler vibrometer and replacing its integrated demodulator with an external demodulator works for primary calibration of accelerometers up to at least 20 kHz, which was the primary goal. The project has also demonstrated that the developed measurement principle could ultimately be further developed for primary calibration of accelerometers with shock excitation.

Expected long term effects

The developed measurement system is expected to be used for regular primary calibrations of accelerometers up to 20 kHz. In addition to the extended frequency range, we also expect to be able to improve our measurement uncertainty within our existing frequency range. The measurement system is expected to be further developed into a system that can also primary calibrate accelerometers with shock excitation, a capability that is not available in Sweden today.

Approach and implementation

When preliminary studies showed that the measurement method generates large amounts of data that require heavy calculations, the project began with experimental tests to reduce the data in an analogous way. The majority of the project time was spent on developing a demodulator in software, which was unexpectedly challenging and resulted in other planned activities being cancelled. The developed demodulator was used in subsequent evaluation tests of the existing vibrator.