Instrumentation:'Seeing' acoustically: New nondestructive techniques permit subsurface examination of materials for density and elasticity

The acoustic microscope — a new tooi that lets researchers see minute structural details of an object by displaying the object's response to ultrasonic sound — is under development in several laboratories. Athough still in an early stage, the technique has already attained resolutions comparable to those of optical microscopes and is demonstrating its potential in increasing applications, from biomedical research to materials science.