Abstract: The vibration of a beam is studied. A scanning laser vibrometer system is used to measure the natural frequency and modal of transverse and longitudinal vibration. The experimental results is well consistent with the theoretical modal analysis results. Compared with the results obtained from traditional transducer measurement, it shows that the measure accuracy can be improved by the laser Doppler technique and the problem of append mass and rigidness to the structure caused from transducer measurement can be solved. The technique is well used especially in the modal measurement of light and thin structure.

Key words: Beam, Laser, Vibration, Modal measurement