研制了一种用于测量海水盐度的新装置。基于表面等离子共振技术，根据盐溶液折射率与盐度的关系原理，实现对盐度测量。结构中使用一只K9玻璃制成的棱镜为衬底，在棱镜的一边淀积一层厚度为55 nm的Ag膜，在Ag膜上设置待测盐溶液样品池和参考池。在白光的激励下，在Ag膜中发生表面等离子共振现象。盐溶液的折射率不仅与盐的质量分数有关，且与温度有关，而样品池和装有蒸馏水的参考池具有相同温度，用两者共振波长差的变化来反映盐度，克服了温度对测量结果的影响，理论分析和实验结果验证了设计的可行性。

A novel device measuring seawater salinity is developed, based on techniques of surface plasmon resonance (SPR) and relation between its salinity and refractive index. In the device, a prism made of K9 glass is used as substrate, and a film of Ag (55nm) is deposited on one side of the prism; after that, two flowing cells are built on the Ag film, one serves as sample solution, and the other as distilled water. Under the excitation of white light, SPR occurs in two areas at different wavelengths. Although the refractive index of seawater is determined not only by its salinity, but also by its temperature, and sample solution and distilled water have the same temperature. If the difference of resonance wavelengths (Δλ) is utilized to indicate the salinity, the affection by temperature drift could be eliminated. Theoretical analysis and experimental result verify the feasibility of the device.