| 摘要 |
<p>An ultrasonic probe is described, for use in a system for measuring the length of a reflecting anomaly in a workpiece. The probe operates to yield an output signal having elements therein directly related to the length of that anomaly, typically, a crack. The probe comprises a first transducer having a face for transmitting an incident beam of ultrasonic irradiation. A second transducer is provided, acoustically non-coupled to the first transducer, and having a face for receiving a portion of the incident beam reflected from an extremity of the anomaly. Directing means are connected to at least one of the transducers, causing the transducers to be oriented in a manner such that orthogonal projections of the transducer faces intersect to define a depth of field in which the extremity of the anomaly is locatable. A probe housing supports the transucers and the directing means. The housing also includes signal conducting means connectible to an ultrasonic source to drive the transmitting transducer, and to signal processing and displaying apparatus for processing the output signal and providing a read-out of the length of the anomaly. In a preferred embodiment, the directing means comprises two similar prisms joined together physically but non-coupled acoustically, with each prism serving to mount a related one of the transducers thereon. In a still more preferred form, the transmitting transducer is of lead zirconate titanate, find the receiving transducer is of lead meta niobate. The two transducer heads are provided in the one ultrasonic probe and measures the length of the reflecting anomaly from a generally "end-on" orientation.</p> |
