Surface Characterization Using the Restricted Aperture Acoustic Microscope
Abstract
A scanning acoustic microscope that uses a novel lens having a slot-shaped aperture is used to investigate the quantitative measurements of properties of isotropic and anisotropic materials and also the characterization of surface-breaking cracks. The slot lens has a point focus and yet launches leaky Rayleigh waves in preferential directions. This allows surface wave velocity measurements of anisotropic materials as well as interrogation of cracks at nearly normal incidence for determination of the crack reflection coefficient. Such a lens can also be used for imaging of polycrystalline material surfaces where contrast depends solely on Rayleigh-wave anisotropy. Diffraction-corrected geometric theory is employed to model the response of both the slot and circular aperture lenses to cracked as well as defect-free sample surfaces. Experimental measurements were made to test the theoretical predictions.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1991
- Accession Number
- ADA356686
Entities
People
- Dmitry Chizhik