QIAN Menglu PENG Ruolong

(Institute of Acoustics,Tongji University Shanghai 200092)

Received Mar.3, 2007

Revised Oct.4, 2007

Abstract  Based on the research in Ref. [5][Materials Science and Engineering, 1989; A 122:57-63], an improved model of heat source is set up, the different modes of Lamb wave in an isotropic sample generated by a chopped electron beam at frequency f are obtained with integral transform and normal function expansion method, and the output signal of PZT coupled at the back surface of the sample is found out. The generation mechanism of SEAM (Scanning Electron Acoustic Microscopy) signal is discussed. It shows that the SEAM is a near field imaging technique with high spatial resolution and its best lateral spatial resolution is about 2 (radical sign) 2a (a is the radius of the focused electron beam). Some of experimental results of SEAM images are presented in the paper and it shows that the spatial resolution of SEAM is better than 0.5um and smaller than the thermal diffusion length of the samples. Therefore the character of neat field imaging in SEAM is also proved experimentally. 　

PACS numbers: 43.35