为了测量不同盐度条件下的海水折射率的变化，进而得到海水的盐度，提出了一种应用菲涅耳定理设计的光纤盐度测量方法。介绍了测量原理和初步的实验结果。该方法简单、快速、准确度及灵敏度高。结果表明，此方法在测量盐度时分辨率好于0.4%，可应用于海水盐度的实时监测等场合；理论上可以测量任何气体、液体和固体的浓度(折射率)，适用于工业在线监测物质的浓度(折射率)。

In order to measure the refractive index of the salt solution so that its salinity can be obtained, a measurement method with optical fiber based on the Fresnel principle was put forward. Its principle was introduced and the experimental results were obtained. The experiments indicated that the resolution was smaller than 0.4%. This method is simple, fast, sensitive and accurate. It can be applied in real-time monitoring of the seawater salinity. It also can be widely used in the field of industrial on-line concentration or refractive detection.