Development Of Radiation Source Control And Signal Acquisition System For New AFS

China is a large market of the application of atomic fluorescence technology,almost all the atomic fluorescence spectrometers?AFS?currently are non-dispersive AFS,which exists spectral interference problems,causing the deviation in the detection results of some elements.Therefore,even though AFS tech in China is in the leading position among the world,it has not been internationally accepted yet.On the other hand,traditional dispersion detection technology has not been further developed due to its own limitations.Fortunately,using high-ultraviolet transmittance digital micromirror device?DMD?as a spatial light modulator for dispersion AFS detection technology would overcome the spectral interference problem,which enable to effectively enhance the competitiveness of China's atomic fluorescence industry,gain a place in the international market and have a broader market.As the urgent need of developing dispersive signal collector as well as the measurement and control system,this paper aims at developing a light source control and signal acquisition system suitable for the new AFS.This system is designed to be applied to the measurement and control system and integrated.The details are as follows:?1?Development of the radiation source control partThe excitation intensity of the excitation source has a direct effect on the atomic fluorescence intensity.In this paper,the high-intensity hollow cathode lamp?HCL?is used as the excitation source to design a dual-channel light source driving circuit.And a light source control hardware is developed and used to work at a specific timing to cooperate with DMD.In this paper,for the two main functional requirements of lamp current setting and lamp type identification,STM32F103C8T6 is used as the light source to drive the control core,and the CAN bus communication and functional lower computer algorithm are designed.?2?Development of signal acquisition partBackground interference from AFS will directly affect the accuracy of the test results,so background subtraction is particularly important.In this paper,the photomultiplier tube?PMT?is used as the detector to design the background subtraction closed-loop circuit,and the frequency response and stability conditions are obtained through simulation.The signal acquisition hardware is developed and used to work under a specific timing to achieve the background subtraction.?3?System integration and timing designThe measurement and control system is a key component of the new AFS,which combines the control units into one unit to work with the upper computer.In this paper,an integrated system for light source control and signal acquisition as well as its interface and layout were designed,and adapter plate was developed.The new AFS principle prototype was built which integrates the original components and newly developed components.Besides,the overall timing is designed for the integrated system of light source control and signal acquisition.?4?Testing and applicationThrough the test,the lamp type identification function,the lamp current setting function,negative high voltage setting function and background subtraction function are realized,and the CAN bus and LVDS bus communication are enabled.The components of the integrated measurement and control system have met the expectation and passed the third party test.Using the light source control hardware,it is proved that the Bi and As elements HCL have the highest SNR at the total current of 60 mA or 110 mA,with the duty ratio of 1:3 and the main/total current of 50%.And dual channel simultaneous lighting is realized.The signal acquisition hardware was used to conduct a sample experiment in the range of 1¹00?gL^-1for Bi.The performance of Bi on the analysis line at 223.06nm was discussed.The maximum SNR was increased by 77.78%.The detection limit was 0.0725?gL^-1,reduced to the original 54.04%,and fitting curve R²=0.9996.In this paper,the light source control hardware developed enables to provide reliable driving for high-intensity HCL;the signal acquisition hardware developed might measure signals and background on the analysis line,and realize fast automatic background subtraction;the new AFS principle prototype was built,which integrates the original components and newly developed components,works coordinately and orderly.