| 摘要 |
PURPOSE: To increase the measuring accuracy of a cycle and to precisely compute a surface-wave speed by a method wherein a function expressing a background curve in which the integrated value of a difference from a reception intensity signal becomes substantially zero is found, it is removed from the reception intensity signal and the cycle of a vibration waveform is computed. CONSTITUTION: Ultrasonic waves are emitted to the surface of a sample 3 from an ultrasonic-wave transmitter-receiver 14, the reception intensity signal of their reflected waves is inputted to a computer 30, and an average signal value UZ is found. Then, on the basis of the signal value UZ, the computer 30 finds a background curve CZ in which the difference from the signal value UZ becomes substantially zero by means of a function in which a reception intensity as a parameter is expressed in the relative position in the Z-direction of an acoustic lens 12 to the sample 3, and it computes a cycle ΔZ at a vibration waveform in which the bias component of the curve CZ has been removed from the signal value UZ. Since an error due to the relative dislocation between a reference material and a test material (the sample 3) with reference to the lens 12 is not contained in the signal value UZ from which the bias component has been removed, the accuracy of the cycle Δ2 which is computed is good, and a surface-wave speed VS which is computed on the basis of it is precise. |
