Design And Implementation Of Data Acquisition System For X Ray Spectrum Measurement Based On FPGA

X ray is a kind of continuous spectrum,that is to say,X ray energy is chromatography,analysis from the perspective of physics,X rays of different energies have different attenuation characteristics,which can reflect the attenuation characteristics of different physical properties of the object to be measured.The mechanism of X radiation and the effect of different material energy is not the same,therefore,in the X-CT system,X ray and the object being detected after the action will produce ray(beam)(Beam Hardening),which is hardened to uniformly center abnormal X-ray attenuation or absorption decreased,which led to CT image "cup(Cupping)" artifact(Artifact).In this case,if we know the energy spectrum of the X ray and the material(the object)before and after the interaction,the CT image can be corrected properly.X ray energy spectrum can be obtained by X ray energy spectrometer,this paper studies a X ray energy spectrum data acquisition system based on FPGA,and the development of the related energy spectrum display software.Through the investigation of the domestic and international X ray energy spectrum data acquisition system,the digital X ray energy spectrum data acquisition scheme based on FPGA is selected.Based on this,this paper uses Altera company EP4CE15 series FPGA chip,ST(STMicroelectronics),STM32F103 series microcontroller,AD9215 analog-to-digital converter as the core device of the acquisition system design of X digital X-ray energy spectrum data acquisition system.Combined with the hardware design of the data acquisition system,this paper describes the detailed design ideas of the pretreatment circuit,power supply circuit,FPGA peripheral control circuit,STM32 peripheral control circuit and ADC sampling circuit.The digital X ray pulse signal processing module is also very important,according to the need,the paper has made the detailed introduction to the FPGA software design,has designed each functional module of the FPGA with Verilog HDL language.System software design includes two parts: STM32 microcontroller software design and PC software design.The STM32 microcontroller not only needs to complete the data transmission and command interaction between USB and FPGA through the SPI interface,but also can transmit the data to the host computer application software through the virtual serial port.The application software of PC,which can display software by using Visual spectrum Studio2010 software development platform using C# language design,X ray energy spectrum data and the pulse signal through the open source data curve drawing control ZedGraph line drawing,but also the X ray energy spectrum for energy calibration,interested area,spectral data storage operation.Finally,after a preliminary test showed that the subject X ray spectrum data acquisition system design,using NaI(Tl)scintillation counter output pulse signal of nuclear testing,realize spectrum data display and storage,but also can complete the energy scale,interested in the area of operation,to achieve the desired design goals.