基于GRIN-Lens散射式红外浊度仪的设计

Design of Scattering IR Nephelometer Based on GRIN-Lens

根据水质浊度测定标准 ISO 7027-1:2016,结合散射法浊度测量原理,设计一种用于测量环境水体浊度的小型化便携式浊度仪。测量光源采用波长为 880 nm 的红外 LED,设计了恒流源驱动电路提高光源的稳定性。浊度仪以嵌入式 ARM 处理器为核心,基于 GRIN-Lens 自聚焦透镜和 TSL2581光强传感器设计检测模块,并通过 OLED 显示屏实时显示测量数据。设计并通过 3D 打印技术加工了机械装置,实现了包括光源、比色皿、检测器和 GRIN-Lens 等结构一体化的测量系统。实验结果表明,浊度仪在0~400NTU的样品中可精确地对浊度进行测量,线性良好,精密度良好,方法检出限为0.2 NTU。

According to the standard of ISO 7027-1:2016,aminiaturized and portable nephelometer based on the scattered light method and the GRIN-Lens was developed for the monitoring of the quality of environmental water.An IR LED of 880 nm was used as the light source,and a constant current circuit was designed for maintaining the stability of the light source.A circuit main board was designed for communication,control,and information collection.The hardware of the main board was based on anembedded ARM microprocessor,integrated with a light intensity detecting module based on the TSL2581,and an OLED screen by which the measurement data was displayed.The GRIN-Lens were used for emitting collimated light and collecting scattered light.The machinery of measurement was machined using 3D printing,and which is a measurement system that integrates light source,cuvette,detector and GRIN-Lens.The detection linear range of nephelometer was 0~400NTU,while the limit of detection was 0.2NTU.