Method and apparatus for detecting internal defects

Abstract

A method and apparatus for detecting internal defects in a workpiece are disclosed which uses time inversion to invert echo signals received by a transducer from the workpiece with respect to the signal shape and its time distribution and retransmits the inverted signal onto the workpiece. The method involves transmitting an unfocused ultrasonic beam onto the workpiece, receiving an echo signal from the workpiece, storing the first echo signal and inverting the first echo signal from each transducer with respect to the signal shape and time sequence. The inverted signal is transferred to a memory and the aforementioned procedure is carried out for each of the inspection zones n on the workpiece. The stored, inverted first echo signals are then transmitted onto the workpiece, each inverted signal being transmitted onto the inspection zone n from which the non-inverted first echo signal was received. A second echo signal is received for each inspection zone n of the workpiece and this second echo signal is also inverted with respect to both the signal shape and the time sequence and again stored in a memory. The second, inverted echo signal may be again be retransmitted onto the workpiece in the same inspection zone n from which the first, inverted echo signal was transmitted. The apparatus used for carrying out this method may comprise an array of ultrasonic transducers located adjacent to the workpiece so as to direct ultrasonic energy onto an inspection zone n of the workpiece, a first memory connected to transducer array to receive first echo signals from the transducer and to invert the echo signals with respect to both the signal shape and the time sequence. A second memory is used to store the inverted first echo signals from the first memory and is connected to the transducer array such that these first inverted echo signals may be retransmitted onto the workpiece in the inspection zone from which the corresponding non-inverted echo signal was received.

Dependencies are inferred from the claim text.