抄録
In this paper we propose a method for discrimination of noise-covered ultrasonic signals by making use of the distinguishing features of signals reflected from electrical trees extending toward the direction of depth within the specimen. That is to say, it utilizes the characteristics of signals due to the spacial continuity of a tree branch and also the change of the delay time of the reflected signal from the electrical tree when the ultrasonic transducer is moved slightly around near the target point over the specimen.
As the results, it is shown that the three-dimensional structure of the bush-type tree in polyethylene can be visualized in non-destructive way. The resultant shapes of the trees are agreed well with those obtained by actual sectioning of the specimen using a microtome.
