| 摘要 |
An ultrasonic probe includes an ultrasonic transducer; a delay line acoustically coupled to the transducer so that ultrasonic vibrations may be transmitted into the delay line from the ultrasonic transducer in a first direction, the delay line includes a first section and a second section; the first and second sections forming an interface that is substantially perpendicular to the first direction; and the second section including a surface for coupling with a material to be investigated. The probe can be used to measure a thickness of a coating on a substrate by transmitting a signal in a first direction from the transducer into the delay line; measuring a time t1 for a first portion of the signal to travel round trip from the transducer and the interface; using the measured time t1 to calculate an expected time t2 for a second portion of the signal to travel round trip from the transducer to an opposite face of the delay line; measuring a time t3 that it takes for a third portion of the signal to travel round trip from the transducer and an interface between the coating and the substrate; and calculating a thickness of the coating based on a difference between the time t2 and the time t3. |
