Acoustic Detector and Generator
Original Publication Date: 1987-Apr-01
Included in the Prior Art Database: 2005-Feb-01
Acoustic detection on solid surfaces has gained much importance recently because of the increasing high-volume automated manufacturing, resulting in the necessity of nondestructive quality control methods at different stages. Acoustic detection is conventionally done by the use of transducers, for example, microphone, piezoelectric transducer, electromagnetic acoustic transducer, or optical detectors. However, all these conventional detectors suffer from a size limitation; i.e., their sensitive area is never smaller than a dimension on the order of 1 micron. This means that acoustic waves traveling ALONG a solid surface of wavelength shorter than 1 micron cannot be detected because the extended lateral size of the detector results in the "washing out" of the effects of "peaks" and "valleys", as explained in Fig. 1.