X射线荧光(XRF)法是实现重金属连续监测的有效方法。为了实现工业环境大气重金属连续监测,样品的富 集及与X射线测量位置的精确定位至关重要。提出了一种采用光电位移传感器检测富集样品滤纸位移,实现富 集样品移动精确定位的方法。以单片机作为核心芯片,研制了该样品定位控制系统。最后,利用样品 定位控制系统进行了一系列样品定位试验。实验结果显示利用光电位移传感器进行多次样品定位的 相对标准偏差约为0.5%,进行100 mm位移精确定位的绝对误差小于0.8 mm,能够满足XRF大气重 金属在线监测装置中的样品定位要求。

X-ray fluorescence is an effective method monitoring the heavy metals successively. To monitor the atmospheric heavy metal in factory on-line, sample enrichment and accurate control of distance between the X-ray detector and the sample are essential. An accurate distance control method, with a photoelectric displacement sensor monitoring the shift of sample, is proposed. With an MCU, the distance control system is worked out. Using the distance control system, a series of sample location control experiment are finished. The relative standard deviation of data is about 0.5%. The deviation is less than 0.8 mm between the actual distance and the exact distance of 100 mm. It is confirmed that this distance control system can afford the sample location requirement of the on-line monitor of the atmospheric heavy metal.