GB1486700A - Ultrasonic delay line of nondispersive mode type - Google Patents

Abstract

1486700 Delay lines MITSUMI ELECTRIC CO Ltd 7 April 1975 [10 April 1974] 14207/75 Heading H3U A non-dispersive ultrasonic delay line comprises a propagation medium having parallel major surfaces, which define a perpendicular A-A, and at least one end face which is inclined at an angle # to the direction A-A, and a transducer mounted on said end face and having its principal surfaces parallel to the end face and a pair of side surfaces which lie respectively in the planes of the major surfaces of the propagation medium. Suppression of echo signals and signals due to modes higher than n=0 is thereby achieved. As shown in Fig. 1B both end surfaces 13a, 13b may be inclined to the major surfaces 14a, 14b. Alternatively the other end surface may be perpendicular to the major surfaces (Fig. 4, not shown) in which case the transducer both transmits and receives the signals. The angle # is preferably selected to be less than that at which spurious signals due to the n = 1 mode become a maximum. The invention may be applied to a multireflection type delay line, Fig. 5A; signals from inclined transducer 62a propagate via side surfaces 65a-65d, of which surface 65c may be slightly arcuate, to inclined transducer 62b. Portions of the major surfaces outside the propagation path are covered with attenuation material 67, e.g. silicone rubber. A method of manufacturing such a delay line from a glass block is described in connection with Fig. 6 (not shown).