表面等离子体共振(SPR)技术中的长程SPR技术的实际应用受其特殊的膜层匹配条件(待测物和第一层缓冲层折射率需相近)限制而很难扩展。为了解决这一问题， 本文提出了一种对称型长程SPR (LRSPR)技术来提高传统LRSPR技术的适用性。设计了一种"缓冲介质层+金属膜+缓冲介质层"的对称型膜层结构，用于打破传统LRSPR折射率匹配条件的制约，并进一步提高电磁场穿透深度和共振峰深度。理论模拟分析了对称型膜层结构，并且自行搭建了基于LED光源的角度谱SPR检测系统。利用该系统进行了不同糖浓度溶液下的折射率分辨率实验，并对数据处理的算法进行了优化。实验测得系统的折射率分辨率达到6.1×10-7 RIU，灵敏度可达1.22×105 pixel/RIU，并且在一定折射率测量范围内具有较好的线性度。

Applications of the Long Range Surface Plasmon Resonance (LRSPR) technology from the SPRs are hard to be popularized because of its special film matching conditions, namely, the refractive index of the buffer layer must be similar to that of the tested sample. To improve the applicability of the traditional LRSPR technology, a symmetric LRSPR technology was proposed. A symmetric film structure ( buffer dielectric layer + metal film + buffer dielectric layer) was designed to break the limitations of the matching conditions and to further improve the penetration depth of electromagnetic field and the resonance peak depth. The symmetric film structure was analyzed theoretically, and an angular spectrum SPR detection system was built by using a Light Emitting Diode(LED) as the light source. The measuring system was used to measure the refractivity resolution of different glucose solutions, and the algorithm proposed was optimized. The results show that the refractivity resolution of the system can reach 6.1×10-7 RIU, the sensitivity is 1.22×105 pixel/RIU and a better linearity is obtained in a refractivity measuring range.