| 摘要 |
<p>The device for measuring the sepn. of two surfaces (S1,S2), partic. the internal dia. of a tube comprises an ultrasonic transducer (2) and an inclined mirror (3) with a central window (5), whereby an ultrasonic wavefront is split into two fractions. One fraction is simply reflected from the mirror to surface (S1) and back via the mirror to the transducer which registers a first echo. The other is reflected from mirror to surface (S1), then through the window to surface (S2), back through the window to surface (S1) and back via the mirror to register as a second echo in the transducer. The time interval between the two echoes is processed to provide a measure of the sepn. of surfaces (S1 and S2).</p> |
