In the determination of chlorophyll with the fluorescence method in the natural water, the suspended particles and colloids will seriously interfere with the incident light and the fluorescence. Based on the analysis of the interaction between light and the measured substances, a high sensitivity, wide range of chlorophyll-a concentration measurement strategy, which combines optical information of fluorescence and absorbance with the CCD integration time transformation method, is proposed. Correspondingly, a novel algorithm, which can significantly correct the attenuation of incident light due to the absorption of suspended particles and the deviation of detected fluorescence caused by the scattered light and reflected light, is proposed to realize turbidity compensation. For verification, a self-designed compact optical experimental device consisting of a single LED and a linear CCD was set up to obtain the fluorescence spectrum and absorbance spectrum simultaneously. The experimental results demonstrate that the compensation strategy can commendably compensate for the impact of the suspended particles. The relative error of chlorophyll-a measurement is less than 5%, even in a high turbidity environment. Furthermore, the minimum detection limit is significantly reduced from conventional 0.01 μg/L to 0.0025 μg/L in the range of 0.0025–130 μg/L with the CCD integration time transformation method, which improves the measurement sensitivity. This device and method have the potential to be applied to the in situ online measurement of chlorophyll-a concentration in natural water.

在天然水中用荧光法测定叶绿素时，悬浮颗粒和胶体会严重干扰入射光和荧光。在分析光与被测物质相互作用的基础上，提出了一种将荧光和吸光度的光学信息与CCD积分时间变换法相结合的高灵敏度、宽范围的叶绿素-a浓度测量策略。相应地，提出了一种新的算法，该算法可以显着纠正因悬浮颗粒吸收引起的入射光衰减以及散射光和反射光引起的检测荧光偏差，实现浊度补偿。为了验证，搭建了由单个LED和线阵CCD组成的自行设计的紧凑型光学实验装置，同时获得荧光光谱和吸收光谱。实验结果表明，补偿策略可以很好地补偿悬浮颗粒的影响。即使在高浊度环境中，叶绿素-a 测量的相对误差也小于 5%。此外，通过CCD积分时间变换方法，在0.0025~130 μg/L范围内，最低检测限从常规的0.01 μg/L显着降低至0.0025 μg/L，提高了测量灵敏度。该装置和方法有可能应用于天然水中叶绿素-a浓度的原位在线测量。