Research On The Key-technology And Applications Of Electron Bombarded Active Pixel Sensor

Low-light Level Detection is developing very rapidly.Various countries have paied great attention on it and have invested a lot of manpower and resources in its research and development.With today’s increasingly urgent demand for digital image devices,Electron Bombarded Active Pixel Sensor(EBAPS)came into public.EBAPS has the advantages of high detection sensitivity,low-light level detection capability,low power consumption,small size,light weight,and low cost,which has a very broad development prospect.In addition,the use of EBAPS for the detection of photon event arrival time also has great application value.Up to now,the research and exploration of EBAPS is still mainly dominated by the United States,while China’s research on it is still in the stage of theoretical study and follow-up.In this paper,through theoretical analysis and simulation,we deeply analyzed the imaging mechanism of EBAPS,and the parameter optimization scheme to improve the spatial resolution and detection sensitivity.Based on the analysis,an EBAPS prototype was built,we studied the linear relationship between the brightness value and the acceleration voltage,and a method of "time-amplitude" conversion was proposed to detect the arrival time of photons.The idea is to infer the arrival time of photons from the brightness value(pulse amplitude)of the electron bombardment imaging by adding an electron bombardment acceleration voltage that changes linearly with time.Compared with the streak camera,which can only measure the arrival time of several photons which incident on the slit,EBAPS can detect multiple incident photon events at the same time,which expand the application field of EBAPS,and also provides a new method for detecting the arrival time of photon events.The specific research contents of this paper are as follows:Firstly,a model of photoelectron transit,scattering and diffusion in EBAPS is established.Through this model,the entire detection and imaging mechanism of EBAPS was studied: the space dispersion,transit time dispersion and transit time of photoelectrons transiting between cathode and anode were studied;the scattering trajectory and gain of EBAPS in the electron multiplication layer were studied;the diffusion trajectories of carriers to the pixel collection area as well as the charge collection efficiency are studied.And the optimized parameter to improve the detection performance of EBAPS is given.Secondly,an UV EBAPS prototype was designed and developed.We use a oblique incidence optical path to separate the light image and the electron bombardment image,which effectively weakens the interference of the direct penetration light on the electron bombardment imaging.The electron bombardment images show that the brightness of electron bombardment imaging is linear correspondence with accelerating voltages.On this basis,in order to solve the problems that the brightness of EBAPS electron bombardment imaging results was weak and the required electron bombardment voltage was too high,an MCP-enhanced EBAPS was designed and fabricated,which improved the electron bombardment imaging brightness and reduced the required electron bombardment acceleration voltage,and the brightness of electron bombardment imaging is still linear correspondence with the acceleration voltage.Finally,a method based on "time-amplitude" correspondence is proposed for 2D imaging and photon arrival time measurement simultaneous.By making the MCP working in the saturation gain mode,the influence of MCP voltage fluctuation and the uneven brightness of the incident light is eliminated.Through static experiments,the linear correspondence between the brightness of electron bombardment imaging and the acceleration voltage is obtained.In dynamic experiments,we use the charging and discharging of capacitor creating a ramp voltage that changes with time,and measured the accuracy of photon arriving time based on the "time-amplitude" conversion method.The experimental results show that the minimum detecting error is 2.5% and maximum detecting error is 8.5% among the detection range of 700 μs.