1、1,第十一章 光的干涉和干涉系统,干涉现象是光波波动性的重要特征 1801年杨氏干涉实验波动理论部分相干理论 应用：测量光谱线的细微结构、测量长度 多种干涉装置：杨氏双缝干涉、迈克尔逊干涉仪等 本章内容：干涉现象、干涉理论和干涉装置,2,第一节 光波的干涉条件,一、干涉现象,1、什么是干涉现象（Interference）,2、相干光波（Coherent wave）和相干光源（Coherent light source）能够产生干涉的光波，叫相干光波；其光源称为相干光源。,3,二、干涉条件,一般情况下，,4,对于两个平面简谐波,5,干涉条件（必要条件）：,6,第二节 杨氏干涉实验 （Youngs
2、 double-slit experiment） 一、干涉图样的计算,1、P点的干涉条纹强度,光强 I 的强弱取决于光程差,7,2、光程差D的计算,光程差：,8,3、干涉条纹（Interference fringes） 及其意义,对于接收屏上相同的x值，光强I相等。条纹垂直于x轴。,9,用光程差表示：,结论： 1、干涉条纹代表着光程差的等值线。 2、相邻两个干涉条纹之间其光程差变化量为一个波长l，位相差变化2p。,在同一条纹上的任意一点到两个光源的光程差是恒定的。,10,11,Interference fringes,Zeroth-order maximum,First-order minim
3、um,First-order maximum,12,4、干涉条纹的间隔,定义：两条相干光线的夹角为相干光束的会聚角，用w表示。,m+1,13,5、干涉条纹间隔的影响因素,1）相干波源到接收屏之间的距离D 2）两相干波源之间的距离d 3）波长,14,干涉条纹间隔与波长的关系,x,0,白条纹,白条纹,白光条纹,15,二、两个点源在空间形成的干涉场,16,在三维空间中，干涉结果：等光程差面,局部位置条纹,17,本课内容回顾,6、干涉条纹间隔与波长：多色光的干涉,7、两个点源在空间形成的干涉场：等光程差面,2、P点的干涉条纹强度：,3、光程差D的计算：,5、干涉条纹的间隔：,1、干涉现象和干涉条件,1
4、8,Key words,1. Path difference 2. Phase difference 3. The order of interference 4. The light distribution 5. A maximum amount of light (maxima) 6. A minimum amount of light (minima),19,Homework (11-1&2),Light passes through two narrow slits of d=0.8mm. On screen 1.6m away the distance between the tw
5、o second-order maxima is 5mm. What is the wavelength of the light?P243 1&2,下一节,20,干涉现象（Interference）,在两个（或多个）光波叠加的区域形成强弱稳定的光强分布的现象，称为光的干涉现象。,The term Interference refers to the phenomenon that waves, under certain conditions, intensify or weaken each other.,21,干涉现象实例（Interference Examples）,22,2,返回,2
6、3,Thomas Young (1773-1829),A British physician and physicist. He could read at age 2, at 6 began studying Latin, and at 13 had also mastered Greek, Hebrew, Italian and French. At 19 he entered medical school, correctly explained the accommodation of the eye and was elected Fellow of the Royal Societ
7、y. In 1796, he graduated from the University of Gottingen Medical School, opened a practice in London, and 5 years later became professor of Natural Philosophy at the Royal Institution. That same year,1801, he read the first of several papers presenting the wave theory of light and the principle of
8、interference, much to the opposition of Newtons followers. Young made noteworthy contributions also to acoustics, atmospheric refraction, elasticity, fluid dynamics and color vision.,返回,24,Interference fringes,The light of distribution resulting from a superposition of waves will consist of alternately bright and dark bands called interference fringes. Such fringes can be observed visually, projected on a screen, or recorded photoelectrically.,返回,
