Research Of PMT Module Gain Regulation Control System Based On FPGA

In recent years,with the continuous innovation of science and technology,more and more fields,such as biomedicine,food safety,industrial construction,national defense-and military,plasma physics,are involved in the detection and analysis of weak light signal,and the precision of weak light signal detection is becoming higher and higher.The detection of weak light signals needs to build a photoelectric detection system.In view of the characteristics of high sensitivity,high gain and low dark current,the Photomultiplier Tube(PMT)is often used in the photoelectric detection system.As the PMT module has the advantages of low power supply,good security,short response time and high signal-to-noise ratio,the use of PMT module is also increasing.For the extremely weak light signal,the appropriate adjustment of the gain of the PMT module is very important.The gain adjustment is too high or too low,which may lead to the phenomenon of peak or annihilation of the weak light signal.The traditional way of PMT module gain regulation is to adjust the control voltage by manually adjusting the voltage by the potentiometer,which depends on the personal experience and the adjustment error is always large,and it can only be adjusted at the experimental site.It is very inconvenient to operate.To solve this problem,a PMT module gain regulation control system based on FPGA is designed.First,this paper explores the domestic and foreign research status of PMT module gain adjustment at home and abroad,derives the specific numerical relationship between PMT module gain and work voltage and control voltage,and analyzes the method of PMT module gain adjustment,and finally determines the way of hardware circuit design and software programming to realize the remote regulation of PMT module gain.Second,the hardware circuit of the PMT module gain adjustment remote control system is designed,and the specific circuit design of the peripheral circuit,the DA data acquisition module,the buffer module and the serial communication module with the FPGA chip as the control core is analyzed in detail.Finally,the software part programming is completed,including two parts:FPGA programming and PC software programming.The program of DA control module and serial communication module written in Verilog HDL language in FPGA programming is introduced in detail,and the correctness of the design program is verified by using the software of Modesim6.6.The subroutine of communication module design using Labview 2014 software is introduced in the programming of upper computer,and the design of upper computer interface and module composition is elaborated.Finally,the results of the PMT module gain adjustment are compared with those of the traditional potentiometers.The experimental results show that the system can realize the remote regulation of PMT module gain.Compared with the traditional adjustment method,the system has convenient operation,good stability and good practical value.