1 GHz differential phase acoustic lens design for surface and subsurface applications

The authors discuss the design of a 1-GHz differential phase acoustic lens for topographical use, and investigate other operating modalities of this design which allow surface and close to surface velocity perturbations to be investigated. Such measurements will give information on surface residual stress and material properties. Computer simulations of the wave propagation for both focused and defocused lenses demonstrate the various capabilities of this lens. Modifications to the design, which is for an isotropic material (e.g. quartz), taking into account a lens rod fabricated from anisotropic materials (e.g. sapphire) are also addressed. The electronics and scanning stages necessary to complete the design of this precision microscope are described