光电成像原理 07

电子运动的近轴（高斯）轨迹方程：

11

性质

高斯光学理想成像性质:

1.从物平面上发出的所有电子，通过场的作用，

能够在像平面上会聚于相应的像点上。

2.像和物的几何形状相似，也就是

说各点的横向放大率与物高无关。

高斯轨迹理想成像的证明：

1

其通解:

初始条件：

电子近轴轨迹的表达式:

像点坐标：

i

z z =平面：

根据轴上电位分布情况

发散会聚发散会聚作用占优势

会聚发散会聚

会聚作用占优势

单透镜是会聚透镜。

z

类似于光学中浸没透镜

两个（或两个以上）同轴圆筒（或膜片）组成

会聚发散会聚作用占优势

发散会聚会聚作用占优势浸没透镜是会聚透镜

将一个带孔的膜片插入平板电容器中间

会聚透镜发散透镜浸没透镜可以是会聚的，也可以是发散的

透镜的加速电场直接和物毗连（一般以阴极作为物），即物浸没在透镜电场内。

3. 阴极透镜聚焦特性分析：

大部分区域，0φ′′>阴极透镜为会聚透镜

C V =0

M V <0

A V

>

用来产生可控并具有一定电流密度、一定形状、往一定方向投射的聚焦电子束。

2. 第二透镜（主聚焦系统，主透镜）

将发射系统出射的电子束聚焦成像

MM型：磁聚焦，磁偏转

EE型：静电聚焦，静电偏转

ME型：磁聚焦，静电偏转

EM型：静电聚焦，磁偏转

不能控制电流，阴极电流饱和

Electron gun

An electron gun(also called electron emitter) is an electrical component that produces an electron beam that has a precise kinetic energy and is most often used in televisions and monitors which use cathode ray tube technology, as well as in other instruments, such as electron microscopes and particle accelerators. Electron guns may be classified in several ways: by the type of electric field generation,

by emission mechanism (thermionic, photocathode, cold emission, plasma source),

by focusing (pure electrostatic or with magnetic fields), or

by the number of electrodes.

Most color cathode ray tubes —

such as those used in color televisions —incorporate three electron guns, each one

producing a different stream of electrons. Each stream travels through a shadow mask where the electrons will impinge upon either a red, green or blue phosphor to light up a color pixel on the screen. The resultant color that is seen by the viewer will be a combination of these three primary colors . Characteristics