Real-time, frequency-translated holographic visualization of surface acoustic wave interactions with surface-breaking defects. 
A real-time, frequency-translated holographic imaging system has been developed by use of bacteriorhodopsin film.  The system provides a capability for imaging surface acoustic waves and has been utilized to detect and characterize surface-breaking defects through near-field ultrasonic scattering effects.  Frequency-plane filtering was used to discriminate between ultrasonic standing-wave and near-field scattering features, dramatically enhancing the holographic visualization of the defect sites.  A detailed description of the system is presented, along with representative holographic images showing the interaction of surface acoustic waves with surface-breaking cracks and small notches in aluminum and titanium substrates.