Vibration Measurement and Analysis Using Heterodyne Laser Detection


An experimental Michelson interferometerarrangement has been implemented utilizing theprinciple of laser Doppler vibrometry. He-Ne laserhas been used as a coherent light source. Thecircuit for heterodyne detection has been built todetect and record Doppler signals. Two types ofmaterials have been used as vibrating panel, whichare excited by acoustic waves applied from aloudspeaker connected to a function generator.The applied waves were in frequency range of 10-100Hz. The recorded results of the experimentalwork demonstrate that the vibration frequency ofthe panel conforms to the applied frequency whenthe ratio between the applied and naturalfrequencies is greater than two (or less than onehalf).