The Development Of Photon Beam Position Monitor System Based On Four-quadrant Detector

For the synchrotron radiation light source, photon beam position monitor (PBPM), as an important part of beam positon monitor(BPM) system, is of very high value for the application reaserch which call for high-quality and high stability.Therefore, many laboratories at home and abroad pay great importance on PBPM system.This paper introduces the working principle of the photoelectric effect , then makes analysis and comparison among the two wire-type detectors, blade-type detectors, face detectors, improved face detector and four quadrant detector performance. PBPM system based on the four-quadrant detector is designed and depth analys is made for various parameters that impact the performance of the four-quadrant detector, including signal processing algorithm, direction ,detector radius, light size,etc .Four-quadrant detector is InGaAs detector, GD3541T and GD3542T.They ,having very fast response time, are ideal photodetectors for synchrotron light source. On this basis, mesurement circuit of PBPM is developed , using computing chips LOG101.The system select the ARM7 as the core of hardware design, including the transplant of embedded operating system-uC / OS-II , as well as procedures for the preparation of man-machine interface.In order to get the calibration coefficients and the linear range ,we calibrate the detector GD3541T and GD3542T vertically and horizontally, respectively. And then apply PBPM system based on the the four quadrant detector in HLS B3A-20, measure the the actual location of synchrotron light, and compare the result with measurement of BQ6E .