| 摘要 |
PURPOSE:To measure the width of a body to be measured with high precision without increasing the number of probes by providing a reference reflecting means with two reflecting surface different in the distance between probes which both receive and reflect the ultrasonic wave of ultrasonic wave probes. CONSTITUTION:The width D of the body 2 to be measured is measured from D=l0-2l3-[(t2-t4)+(t3-t4)]X l1/t1. In the equation, l0 is the distance between ultrasonic probes 4 and 5, l1 is the distance between reflecting surfaces B8 and B9, and l3 is the distance between an ultrasonic wave probe 3 and the reflecting surface B8; and t1-t5 are propagation times in which an ultrasonic wave travels by the distance l0, the distance between the probe 4 and objective body 2, and the distance between the probe 5 and objective body 2, and the distance l3. In this case, l3 lx1 lx2, so t2 t4 and t3 t4, so that even if there is an error in reference ultrasonic propagation speed l1/t1, it does not exert much influence upon the size D. The size D is therefore measured with high precision. |
