Abstract

It was demonstrated¹ that sub-optical (<2000 Å) resolution can be achieved in a scanning acoustic microscope using piezoelectric excitation and water as the coupling medium. The resolution limit is set by (1) the upper frequency of 2-4 GHz of acoustic transducers and (2) by strong ultrasonic wave attenuation in water, which increases as the square of the frequency. The piezoelectric excitation scheme sets narrow limits on the achievable power levels, which is mainly caused by the damage threshold of the piezoelectric transducers by an applied electric field.

© 1998 Optical Society of America