| 摘要 |
PROBLEM TO BE SOLVED: To effectively and surely carry out a thickness measurement without having adverse influence on an object to be measured. SOLUTION: When carrying out measuring the thickness of a lens 15 in such a way that arrival time intervals between reflected waves being ultrasonic waves generated from an ultrasonic sensor 40, one of which arrives from the surface of the lens 15 and the other of which arrives from the rear face of the lens 15, are observed, and the distance between the surface and the rear face is calculated from the arrival time intervals, states of the reflected ultrasonic waves arriving thereat are monitored. When such a judgement that the lens 15 is placed at a position where above measurement can be carried out, is made based on monitored results, the measurement is carried out in this positional condition. COPYRIGHT: (C)2004,JPO&NCIPI
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