| 摘要 |
PROBLEM TO BE SOLVED: To measure thickness accurately by using ultrasonic even a measuring object from which only a little reflection wave can be obtained. SOLUTION: The difference in arrival time of reflection wave of emitted ultrasonic is observed between a wave from the front surface of the measuring object and a wave from the back surface of the measuring object. The thickness of the measuring object is measured for a plurality of times by calculating the distance between the front surface and the back surface from the difference of the arrival times, and a plurality of measured values showing the thickness of the measuring object at every measurement are obtained in processes from S30 to S32. In the process of measured value processing S33, the measured values regarded not affected by noise erroneously observed as reflection wave are extracted from the measured values, and the thickness of the measuring object is calculated based on the extracted measured values. The calculated values are exhibited as the measured result of the thickness of the measuring object in the process S34. COPYRIGHT: (C)2005,JPO&NCIPI
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