| 摘要 |
<p>An instrument for measuring the distance of a body in relative motion away from a datum point measures the optical attenuation of an optical fibre that has an end secured to that datum and extends to the body where the remainder of the fibre is coiled. As the body moves away, so progressively more fibre is uncoiled, and the contribution of bending losses to the total loss is reduced and hence the resulting reduction in attenuation provides a measure of distance travelled.</p> |
