基于MCP的快速光子计数成像系统的设计方案

摘要

通常基于MCP的阳极探测系统获得图像的速度受到噪声和信号处理速度的限制,影响了图像的时间分辨率和空间分辨率.介绍了一种快速光子计数成像探测器,使用的阳极结构避免了需要高信噪比的信号测量电路,及模拟信号到数字信号的转换,缩短了电子信号处理的时间,能有效提高图像质量.阳极面板依据格雷码编码方式划分区域,因此从微通道板出来的电子云在位敏阳极上的质心位星,由成对电极上的电荷比较值来确定,省略了由模拟信号变为数字信号的过程.所以对比较器的要求较高,要有高的运算速度,前端电子学具有高速、低噪、线性的特性.在此对快速先子计数成像系统提出了整体设计方案,并得到初步的实验结果,证实方案可行.%The image acquisition speed of positive pole detection system with MCP is usually limited by noise and signal processing speed, which reduce the time resolution and space resolution. A fast photon counting imaging system is introduced in this paper. The anode structure used in the detector avoids the demand of the signal detection circuit which requires high signal to noise ratio and analogue to digital conversion, curtails the time of signal processing* and improves the image quality effectively. The anode panel is divided according to the coding mode of Gray code, so the centroid position of electronic cloud on the position sensitive anode, coming form MCP, is determined by charge comparing values on pairs of electrodes. It omits the converting process of analogue signal to digital signal. Therefore, it requires very high-speed comparators. The front-end electronics has the characteristics of high-speed, low-noise and linear response. A design scheme of the fast photon counting imaging system is put forward in the article. The preliminary experiment results have been achieved. It confirms that the scheme is feasible.