高灵敏度浓度测量及显示系统设计

Design of high sensitivity detection and display system for concentration measuring

随着对环境污染的日益重视,污染物质的浓度检测在大气污染检测、高温燃烧环境监测、工业废水排放监测,以及在造纸、食品加工等领域有着越来越重要的作用.我们在分光光度计光谱定性测量的基础上,以甲基橙水溶液做为指示剂,设计制作了基于激光吸收光谱技术的差分式高灵敏度浓度测量及显示系统,通过实验测量得到了甲基橙的电压-浓度标准输出曲线.此系统利用多次反射长程吸收池,大大提高了浓度测量的灵敏度;利用光电二极管偏置放大实现了光电变换,减小了暗电流及热噪声;利用差分式光学检测及数字电路处理方法,有效地抑制了激光器能量起伏及探测器、电子元件的低频噪声的影响.

Concentration measurement is more and more important in environmental pollution monitoring,high temperature combustion monitoring,industrial wastewater emission,and industrial controlling. Based on qualitative measurement of methyl orange by spectrophotometer,a photoelectric detection and its display system with high sensitivity are designed. The laser is used as the light source to achieve multi- way absorption in order to obtain high sensitivity. The dark current and thermal noise are suppressed by using linear photodiode. The energy fluctuation of the laser is eliminated by using the difference method. Moreover,digital computing circuit is designed in order to decrease electronic noise.