E15光的衍射1.ppt

Chapter15 Diffraction of light
§1 The diffraction of light wave
§2 Huygens---Fresnel principle
§3 Fraunhofer diffraction by a slit
§4 Fraunhofer diffraction by a circular aperture The resolving power of optical instruments
§5 Diffraction by a grating
§6 The diffraction of X- rays Bragg condition
§7 Application
大学物理
主讲
许丽萍
University Physics
Chapter18 Diffraction of light
§1 The diffraction of light wave
§2 Huygens---Fresnel principle
§3 Fraunhofer diffraction by a slit
§4 Fraunhofer diffraction by a circular aperture The resolving power of optical instruments
§5 Diffraction by a grating
§6 The diffraction of X- rays Bragg condition
§7 Application
§1 Diffraction of light wave 光的衍射
1 The phenomena of diffraction
(1) Diffraction by a single-slit 单缝衍射
(2) Diffraction by a circular aperture 圆孔衍射
(3) Diffraction by a grating 光栅衍射
2 The classification of diffractions 衍射分类
(1) Frensnel diffraction 菲涅耳衍射
The distance between obstacle and light source or screen are finite
(2) Fraunhofer diffraction 夫琅和费衍射
The light source and screen are infinite from obstacle

Light source
screen
obstacle

light
source
screen
obstacle
3 The purpose to research diffraction
(1) In theory:
Research wave property of light
(2) In practice
Optical spectrometer 光谱仪
(3) Resolving power 分辨率 分辨本领
 Eyes 眼睛：
The limit of resolution of eye: 1'；
 Visible light microscope可见光显微镜：
The limit of resolution of visible light microscope: " The resolving power is 2000 times of eyes；
 Electron microscope电子显微镜：
The limit of resolution of electron microscope: "
The resolving power is 1000 times of visible light microscope ；
可以分辨约为30Å 的两物点
§2 Huygens-Frensnel principle
1 Huygens principle 惠更斯原理
Every point on a wave front can be regarded as the center of a secondary disturbance which gives rise to spherical wavelets;
The position of the wave –front at any later time is the envel