给出了两种方法，用于监测机械和环境试验期间光纤和光缆的光学透射率变化。它提供了由于光学不连续性、物理缺陷和衰减斜率改变而引起的光传输特性变化的监视器。这些方法是通过发射功率和后向散射改变透射率。它们适用于多模和单模光纤。

Gives two methods for monitoring the changes in optical transmittance of optical fibres and cables that occur during mechanical and environmental testing. It provides a monitor in the change of optical transmission characteristics arising from optical discontinuity, physical defects and modifications of the attenuation slope. The methods are the change in transmittance by transmitted power, and by backscattering. They apply to both multimode and single-mode fibres.