Image formation in electron thermoelastic acoustic microscopy

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Abstract
The theory of electron beam acoustic imaging with acoustic wave generation through the thermoelastic effect, or electron thermoelastic acoustic microscopy, has been developed in three dimensions. Images are created through two separate processes: acoustic wave (vibration) generation and acoustic wave transmission. Acoustic wave generation through the thermoelastic effect depends on the material’s thermal and elastic properties. Images based on these properties with resolution on the order of 5 μm is possible. The effect of imaging at different frequencies and phase angles is considered, both theoretically and experimentally, with an integrated circuit. Acoustic wave transmission affects the image by introducing vibrational patterns. This phenomenon was studied with aluminum foil. The effect of acoustic transmission on the image can also be used to detect subsurface cracks, delaminations, and voids. The detection of a delamination in glass at a depth of 25 μm is demonstrated.