一种用于二次电子探测的放大电路设计  

An amplifier circuit design for secondary electron detection

作　　者：崔永俊 曾令通 尉东光 CUI Yongjun;ZENG Lingtong;WEI Dongguang(School of Instrumentation and Electronics,North University of China,Taiyuan 030051,China;Suzhou Institute of Biomedical Engineering,Chinese Academy of Sciences,Suzhou 215004,China)

机构地区：[1]中北大学仪器与电子学院,山西太原030051 [2]中国科学院苏州生物医学工程研究所,江苏苏州215004

出　　处：《电子设计工程》2025年第3期87-91,共5页Electronic Design Engineering

摘　　要：扫描电子显微镜具有非常快的扫描速度,最快可达纳秒级别。而且二次电子信号非常微弱,信号能量仅在50 eV以内。为了更好地实现二次电子信号的成像,通常需要对二次电子探测的放大电路进行专门设计。该放大电路设计采用了ADA4817-1高速低噪声集成运算放大芯片,并设计了一种光电倍增管低噪声前置放大电路,该前置放大电路引入了电源前端滤波以及加法电路。不但实现了稳定放大二次电子信号,提高扫描图像的信噪比等功能,而且能够通过电路线性调节二次电子图像的对比度与亮度。结合信号处理系统,达到了对光电倍增管100 kHz以内的信号增益为27 dB且不失真的目的,从而显著提高了二次电子探测器的分辨率。Scanning electron microscopes have very fast scanning speeds,as fast as nanoseconds.Moreover,the secondary electron signal is very weak,and the signal energy is only within 50 eV.In order to better realize the imaging of secondary electron signals,it is usually necessary to specially design the amplification circuit for secondary electron detection.This amplifier circuit design uses the ADA4817-1 high-speed low-noise integrated operational amplifier chip,and designs a photomultiplier tube low-noise preamplifier circuit.The preamplifier circuit introduces power supply front-end filtering and adder circuits.It not only achieves functions such as stably amplifying secondary electron signals and improving the signal-to-noise ratio of scanned images,but also can linearly adjust the contrast and brightness of secondary electron images through circuits.Combined with the signal processing system,the signal gain of the photomultiplier tube within 100 kHz is 27 dB without distortion,thereby significantly improving the resolution of the secondary electron detector.

关 键 词：光电倍增管 放大电路 二次电子 扫描电子显微镜 滤波器 

分 类 号：TN2[电子电信—物理电子学]