DEVELOPMENT OF INTERFEROMETER FOR ACOUSTIC-EMISSION TESTING

The characterization of the exact response of an acoustic emission sen sor is of fundamental importance for the quantitative nondestructive e valuation of engineering components. To effectively determine an acous tic emission source. the influence of the sensor on the measured wavef orm must be determined. A heterodyne interferometer is developed and t ested for the detection of acoustic emission signals. This optical dev ice makes localized absolute measurements of out-of-plane surface velo cities with very high fidelity- An important feature of this system is that a linear frequency modulation (FM) discriminator is used to demo dulate the carrier signal; as a result, the interferometer behaves as a Doppler-shift detector. A series of experiments was performed to tes t the response of commercially available, piezoelectric acoustic emiss ion transducers in order to understand their potential influence on a measured acoustic emission waveform.