电荷载流子倍增输出概率分布对图像均匀性影响因素研究

Influencing Factors of Image Uniformity Affected by Output Probability Distribution of Charge Carrier Multiplier

为了研究电子倍增电荷耦合器件(EMCCD)中电荷载流子倍增(CCM)结构的输出概率分布及其对图像均匀性的影响,建立了EMCCD中CCM结构的概率模型,利用概率生成函数(PGF)推导了多级CCM倍增结构的输出概率密度函数(PDF),讨论了PDF在提高图像均匀性中的应用。仿真及实验结果表明:当输入信号一定时,输出图像均匀性随倍增增益的增加而逐渐变差;当倍增增益一定时,输入信号越大则输出图像均匀性越差。因此,EMCCD在微光探测条件下图像均匀性较好,且适当地降低倍增增益有利于提高输出图像的均匀性。

The output probability distribution of charge carrier multiplier （CCM） structure from the electron multiplying charge-coupled device （EMCCD） and its influence on image uniformity are studied. The probability model is established for the CCM structure of EMCCD. And based on the probability generating function （PGF） and its properties, the probability distribution function （PDF） of multiple CCM stages is deduced and its application in improving image uniformity is also discussed. The simulation and the experimental results show that： when the input signal is fixed, the higher the multiplication gain is, the poorer the output image uniformity is; when the multiplication gain is fixed, the stronger the input signal is, the poorer the output image uniformity is. As a conclusion, the image uniformity of the EMCCD under the low light level performs better. The output image uniformity is improved by appropriately decreasing multiplication gain.