The present invention relates to a novel device with an ultrasonic based drill and corer. The invention uses ultrasonic and subsonic vibrations, which is produced by a frequency compensation coupler or free mass, to produce the hammering action with relatively low axial-force required. The invention...http://www.google.es/patents/US6689087?utm_source=gb-gplus-sharePatente US6689087 - Floating probe for ultrasonic transducers
