Journal of Vibration and Sound

Journal of Vibration and Sound

Measuring the instantaneous vibration velocity of the speaker with controlling its correct performance using a laser Doppler vibrometer

Document Type : research article

Authors
Farshid Seydipour 1
Fatemeh Rezaei 2
1 Department of physics, K.N.Toosi University of technology
2 Department of physic,, K.N. Toosi university of technology, Tehran, Iran
Abstract
Laser Doppler vibrometers (LDV) are one of the most accurate measurement tools in which the basics of laser interferometry and the Doppler effect are used to measure the vibration characteristics of the objects. These devices are able to measure the vibration velocity from one per hundred of micrometers per second up to tens of meters per second with the highest accuracy. There are many arrangements of LDV, in each of them different analog or digital processors can be used to extract the signal. In this research, at first, the interference signal is simulated and the vibration speed was calculated using the zero-crossing counting method. Then, the single photodiode homodyne Michelson LDV arrangement was used experimentally with the help of analog and digital processes such as zero-crossing counting and moving averaging to measure and control the vibration speed of a speaker. The results showed that by applying a frequency of 17 Hz to the speaker, its vibration velocity was calculated in order of 1 μm/s. Moreover, before and after applying the moving average, the speaker speeds were compared and it was found that after removing the noise, the signals show the moving speed of the vibrating object more accurately.
Keywords
Laser Doppler vibrometer
LDV
Michelson Interferomter
Homodyne laser doppler Vibromtery
Subjects
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