Air-coupled transducers in less than MHz range have been known for some time.  However, non-contact transducers up to MHz with sensitivity only 30 dB lower than conventional contact transducers described here, open new possibilities for industrial and bio-medical applications.  In comparison the NCU mode rivals the contact liquid-coupling mode of ultrasound.  This development in conjunction with the NCA 1000 now allows execution of routine NDE tasks plus analysis equivalent to materials characterization methods based on other wave phenomena.

High Frequency Non-Contact Ultrasonic Analysis: A Practical Reality