| 摘要 |
PROBLEM TO BE SOLVED: To measure the accurate thickness of a material from a detection signal which is acquired at an application point of laser light for ultrasonic wave generation, and has a low-signal level with plasma shock waves removed therefrom thereafter. SOLUTION: Laser light L1 for ultrasonic wave generation is applied to the front face P1 of a plate P, to make ultrasonic wave S generate inside the plate P as a measured material. The vibration of a surface of the material at an application point A of the laser light L1 for ultrasonic wave generation is detected by means of a laser light L2 for detection, with the vibrations caused by reflected wave Sr being reflected by the rear face P2 of the plate P. Shock wave components of a detection signal 5a of the laser light L2 are removed to execute autocorrelation processing for the remaining signal components, and thereby a cyclic signal is acquired, and plate thickness is calculated, based on the peak intervals of the cyclic signal. COPYRIGHT: (C)2011,JPO&INPIT |
