ACCURACY IMPROVEMENT OF RECONSTRUCTION IN NEAR-FIELD ACOUSTICAL-HOLOGRAPHY BY APPLYING DATA EXTRAPOLATION METHOD

Near-field acoustical holography (NAH)) is a non-contacting measuremen t method to visualize structural vibrations by means of backward recon struction. A relevant data-smoothing process is necessary for the NAH experiments. We had previously proposed a new data-smoothing method wi th the aid of data extrapolation. In this paper, we report the effecti veness of this proposed method based on the experimental results. Furt hermore, our data-smoothing method is modified for applications to the generalized NAH (GENAH). The experimental results show that the recon struction error of the surface velocity by the proposed method is less than one-fifth of that by the conventional real-space window method f or S/N = 33 dB. There results indicate that the prospect of improving the accuracy of reconstruction in NAH for the quantitative analysis of structural vibrations is obtained by the proposed method.