Applications for New Electromagnetic Saw Transducers.

摘要

In this paper we describe new electromagnetic SAW transducers (EMT) made from commercially available, flexible, multiconductor flat cable. These transducers offer many advantages, such as conformity to surface curvatures, low cost, ease of fabrication, and design flexibility. Transducers we made include light weight, highly compact, and inexpensive units with small, self-contained, state-of-the-art permanent magnets. These EMT's offer MHz center frequencies, hand-held operation, and promising nondestructive testing (NDT) applications. In one NDT experiment with EMT's, we measured reflection coefficients for SAW on precision, surface downsteps; the results confirm the characteristic behavior of the corresponding theory of Munasinghe and Farnell. In another experiment, we made differential SAW velocity measurements with 0.1% precision - precise enough to discriminate between various surface surface finish types. Finally, by contactlessly launching SAW's on a rotating cylinder by means of curved, surface conforming EMT's, we easily measured rotation rates of 2 rev/day. Rotation rates of 0.01 degree/day are foreseen. (Author)