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.
© 2002 Optical Society of America
(090.0090) Holography : Holography
(120.0120) Instrumentation, measurement, and metrology : Instrumentation, measurement, and metrology
(120.4290) Instrumentation, measurement, and metrology : Nondestructive testing
James L. Blackshire, Shamachary Sathish, Bradley D. Duncan, and Mike Millard, "Real-time, frequency-translated holographic visualization of surface acoustic wave interactions with surface-breaking defects," Opt. Lett. 27, 1025-1027 (2002)