In this paper we propose a method of analysing surface acoustic waves (SAWs) propagating obliquely under a metallic grating with finite thickness. The discrete Green function originally developed for SAWs longitudinally propagating under the metallic grating is modified, and applied to the characterisation of obliquely propagating SAWs. The method is applied to the analysis of Rayleigh SAWs obliquely propagating on 128° Y X-LiNbO3 (128-LN), and the result is shown to be in good agreement with experiments. Leaky SAWs obliquely propagating on 36° Y X-LiTaO3 (36-LT) are also analysed and compared with the result obtained for 128-LN.

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We describe results of experiments and numerical simulations on transducer arrays and the apparatus used to drive them. Thses devices were fabricated for rapid data acquisition in ultrasonic diffraction tomography. The arrays are made by evaporation coating on piezoelectric ceramic substrates and the interval between the elements is using by the theory of acoustic holography. One of two similar arrays is used as the transmitter and the other is used as the receiver. In the experiment on a thin wire object it is proved that the interval is sufficient and that spline interpolation is effective, although the problem remains that the performance of each array element is different. The numerical simulation for the thick object shows, however, that the resolution of the reconstructed image is degraded. Because the element interval is inappropriate in this case.