针对藻类叶绿素荧光信号微弱难以准确检测的问题,提出了基于m序列调制技术的叶绿素荧光检测系统。 分析了荧光检测电路的噪声特点,设计了基于T型电阻反馈网络的I/V转换电路和二级放大电路；根据m序列解调原理, 设计了双极性转换电路、移相电路和基于AD630的荧光信号解调电路。将系统应用于蛋白核小球藻叶绿素荧光检测, 结果表明,对于叶绿素浓度为10 μg/L的蛋白核小球藻,测量相对标准偏差为2.61%。在0～100 μg/L叶绿素 浓度范围内,检测系统输出直流电压值与蛋白核小球藻叶绿素浓度之间的线性相关系数达到0.998。

According to the problems in the detection of weak chlorophyll fluorescence, a chlorophyll fluorescence detection system based on m sequence modulation technology was proposed. On the basis of noise analysis of fluorescence detection circuit, I/V conversion circuit and secondary amplifier circuit that based on T-type resistance feedback network were designed. According to the principle of m sequence demodulation, a bipolar conversion circuit, a phase-shift circuit and a fluorescence signal demodulation circuit based on AD630 were designed. The system was applied to measure the chlorophyll fluorescence of chlorella pyrenoidosa. For a sample with a chlorophyll concentration of 10 μg/L, the relative standard deviation of measurement values was 2.61%. The linear correlation coefficient between the output DC voltage and chlorophyll concentration was 0.998 in a chlorophyll concentration range of 0～100 μg/L.