| 摘要 |
PROBLEM TO BE SOLVED: To correctly measure an edge ratio even in a state that the fluctuation in lift-off is generated by correcting the propagation time on the basis of the predetermined relationship between the intensity of the ultrasonic plate wave detecting signal and the propagation time, and the intensity of a signal detected by a receiving probe. SOLUTION: A transmitting probe 51 and a receiving probe 52 are set a material 63 on a fixed table 1 in a state that rolling is directed in a predetermined direction, and integrally rotated and vertically moved by a rotating and vertically moving device 4. The pair of transmitting and receiving probes can set to the direction of rolling of the material 63 at 0 deg., 90 deg. and ±45 deg.. In a case when lift-off is fluctuated by the set angle of the pair of transmitting and receiving probes, a table determining the relationship between the intensity of the detecting signal of the ultrasonic plate wave and the propagation time is determined in advance for correcting the influence by the lift-off to the obtained propagation time, and the propagation time obtained by the waveform detector 60 is corrected on the basis of the intensity of the detecting signal of the ultrasonic plate wave detected by the receiving probe 52, and the table. |
