一种基于表面等离子共振的液体折射率测量系统  

Refractive Index Measurement System of Liquid Based on Surface Plasmon Resonance

作　　者：陈强华[1] 刘景海[1] 罗会甫[1] 何永熹[1] 罗军[1] 王锋[1] 

机构地区：[1]北京理工大学机械与车辆学院,北京100081

出　　处：《光学学报》2015年第5期158-164,共7页Acta Optica Sinica

基　　金：国家自然科学基金(51005022);北京高等学校"青年英才计划"(YETP1162);北京理工大学基础研究基金

摘　　要：折射率是反映物质信息的重要物理量,在化学、生物、医药等领域中,经常需要将样品制成低浓度溶液进行化学或物理反应,通过对其折射率微小变化的检测来测定样品的各种性质及参数。为此,提出了一种利用表面等离子体共振传感原理测量液体介质折射率的激光相位测量方法,采用Kretschmann结构并建立模型。理论分析表明,在1.333~1.336的折射率变化范围内,反射光p、s分量相位差的变化与折射率变化呈近似线性关系,并由此得到测量公式。设计并搭建了基于双频激光外差干涉光路的折射率测量系统,系统具有良好的共光路结构,抗干扰能力强,信号处理采用相位调制方法,光路结构简单,测量精度较高。通过甘油溶液折射率测量实验表明其与理论分析结果一致,且与其他方法的结果吻合,两者的相互误差小于2.0×10^-5。该方法可广泛应用于生物检测、化学分析、环境污染研究、医学诊断、食品卫生检测等领域。Refractive index is an important parameter who indicates the material information. In chemistry, biology, medicine and other fields, the samples are usually made of low concentration solutions for chemical or physical reactions, from which various properties and parameters of the samples are determinated by detecting small changes of the refractive index of the solutions. So that, a kind of laser measurement method for liquid refractive index is presented based on surface plasmon resonance （SPR） and phase detection. The theoretical analyses indicate that the phase difference change between p and s polarization components of the reflected light is almost linear with the fluctuation of the refractive index at the range of 1.333-1.336. Thus the measurement equation is derived. Corresponding refractive index measurement system is built based on a heterodyne interference optical path using a dual-frequency laser. The system has strong anti-interference ability because of the common light path and high precision because of using phase measurement. The experimental results of measuring glycerine solution refractive index are consistent with the theoretical analysis, and agree with the results of another method, where the error between each other is less than 2.0×10^-5. The method can be widely applied in the fields of biological detection, chemical analysis, medical diagnosis, pollution research and so on.

关 键 词：测量 相位测量 液体折射率 表面等离子体共振 

分 类 号：TP212.14[自动化与计算机技术—检测技术与自动化装置] TN247[自动化与计算机技术—控制科学与工程]