SIMULTANEOUS MEASUREMENT OF MATERIAL CHARACTERISTICS OF LAYERED STRUCTURES BY A SINGLE ACOUSTIC INTERROGATION

Conventionally, ultrasonic techniques extract material features from t he echo return which consists of impulse signals convolved with the tr ansfer function of the medium being investigated. In most cases, only a single parameter such as the boundary reflection coefficient, acoust ic impedance, or velocity of propagation is used for material identifi cation. For a more complex medium, however, it is desirable to utilize as many parameters as possible from a single trace of echo return to characterize material such that a higher precision of identification c an be achieved. The advantage of our approach is that the information obtained is based solely on the echo return from the successive acoust ic interfaces without using the signature of the incident pulse which is rather difficult to capture experimentally. An additional feature o f this method is that it works rather well even in a noisy environment .