Noncontact Excitation of an Acoustic Guitar using the Ultrasound Radiation Force

Dr. Thomas Huber

Gustavus Adolphus College


To make the scans below, the new Polytec PSV-400 scanning laser Doppler vibrometer at Gustavus Adolphus College was used.

The current experiment shows that ultrasound radiation force excitation can be used as a noncontact method for modal excitation as an alternative to a standard mechanical shaker for objects as large as a guitar. By using both the ultrasound excitation and Polytec vibrometer, it is possible to perform completely noncontact modal analysis!

It has now been demonstrated that the ultrasound radiation force can be used for non-contact excitation of objects ranging in size from atomic force microscope microcantilevers and other MEMS devices 300μm in length, to hard drive suspensions and centimeter-scale cantilevers, to an object as large as an acoustic guitar. The exact same ultrasound transducer was used for non-contact excitation of all of these objects, ranging from less than 100 Hz for the guitar, to over 200 kHz for MEMS microcantilevers.