The Algorithm Of Readout Circuit For Far Ultraviolet Photon Counting Imaging

Airglow and aurora are important natural luminescence phenomena that occur in the Earth's ionosphere,and their appearance is closely related to the intensity of solar activity and the intensity of geomagnetic activity.The density of the ions and neutral particles of the ionosphere can be determined by the detection of the far ultraviolet part of the airglow and the aurora that can provide evidence to study the energy transfer between the magnetosphere and the ionosphere.The radiation from the Earth doesn't effects the density of far ultraviolet.So the detection of the far ultraviolet has become the ideal means of the detection of ionospheric.The far-ultraviolet radiation of airglow and aurora belongs to the weak light signal.The detection of the weak light signal by the photon counting technique has many advantages compared with other simulation detection methods,such as good anti-drift,high sensitivity,high signal noise ratio,better time stability and so on.The two-dimensional detector based on the microchannel plate is the ideal single photon imaging detector to realize the weak gas detection.The detector uses the photocathode of cesium iodide to convert the incident photons into photoelectrons.And the electrons are multiplied by the microchannel plate to form an electron cloud.The electronic cloud emitted by the microchannel plate retains the position information of original photon.The charge can be collected by the anode and the position of photon can be calculated in the electronic readout circuit to realize the detection of the two-dimensional image signal.In this thesis,the main work based on the research of status at home and abroad,aiming at the detection of airglow and Aurora,are completed arround the prototype of the far-ultraviolet photon counting imaging detector.(1)The software is written by using LabVIEW to control the FPGA to complete the data collection,transmission and imaging.And the dark-noise and the maximum counting rate of the prototype were tested.(2)A correction algorithm for the shape distortion of the detector is designed by using the MATLAB.The dynamic link library is written in C language to implement the correction algorithm to be used in the host computer software.And the feasibility of the algorithm is verified by experiments.(3)The high-speed digitizer NI5105 of the National Instrumets is used to build high-speed signal acquisition system,instead of the schemes based on FPGA.By comparing the two kinds of signal acquisition scheme,the factors that limit the maximum counting rate of the prototype are analyzed.