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为了进一步提高相位调制型表面等离子体共振(SPR)测量技术的分辨率,从相差信号解调算法方面进行了优化。基于马赫-曾德尔干涉仪结构的相位调制SPR系统中,携带传感信息的p光干涉信号与进行参考的s光干涉信号间存在着相位差。使用光电探测器和数据采集卡将两路干涉光信号采集到PC机,再结合数学计算理论和信号处理原理,最终通过设定逻辑条件选取出较理想的波形、运用锁相的思想对参与解调的光信号进行锁定、利用信号处理原理对2路光信号进行相应的处理,分析了2路干涉光在同一时刻的相位差异。基于该相差信号解调算法,一段时间内相位差异的起伏为0.006°,实现了4.7×10-7RIU(RIU表示单位折射率)分辨率的折射率测量。
In order to further improve the resolution of the phase-modulated surface plasmon resonance (SPR) measurement technique, the phase difference signal demodulation algorithm is optimized. In phase-modulated SPR systems based on the Mach-Zehnder interferometer structure, there is a phase difference between the p-light interference signal carrying the sensing information and the s-optical interference signal subjected to the reference. Photodetector and data acquisition card are used to collect two interfering optical signals into a PC. Combined with mathematical calculation theory and signal processing principle, the ideal waveform is finally selected by setting the logic conditions. The phase-locked Tune the optical signal to lock, the use of signal processing principle of the 2-way optical signal corresponding processing, analysis of the two-way interference light phase difference at the same time. Based on the phase difference signal demodulation algorithm, the fluctuation of phase difference over a period of time is 0.006 °, which realizes the measurement of the refractive index of the resolution of 4.7 × 10 -7 RIU (RIU means unit refractive index).