A high spatial resolution phase-sensitive technique employs a scanning
near field ultrasound holography (SNFUH) methodology for imaging elastic
as well as viscoelastic variations across a sample surface. SNFUH uses a
near-field approach to measure time-resolved variations in ultrasonic
oscillations at a sample surface. As such, it overcomes the spatial
resolution limitations of conventional phase-resolved acoustic microscopy
(i.e. holography) by eliminating the need for far-field acoustic lenses.