光的干涉和干涉系统精.ppt

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1、光的干涉和干涉系统1第1页，本讲稿共36页Wnonnoh21反射光：0.9,0.009,0.0073,0.00577,0.0046.1当平板镀膜且膜层无吸收时当平板镀膜且膜层无吸收时 0.9透射光：0.01,0.0081,0.00656,0.00529,0.00431.2第2页，本讲稿共36页二、平行平板的多光束干涉LP1、干涉场的强度分布（1）光程差与位相差（相邻光束之间）3第3页，本讲稿共36页aarattr expi4第4页，本讲稿共36页（3）反射光的和振幅与光强分布证明5第5页，本讲稿共36页（4）透射光的光强分布6第6页，本讲稿共36页7第7页，本讲稿共36页结论：反射光干涉场与透

2、射光干涉场亮暗条纹互补。结论：反射光干涉场与透射光干涉场亮暗条纹互补。反射场干涉条纹对比度好。反射场干涉条纹对比度好。透射场的亮条纹亮。透射场的亮条纹亮。8第8页，本讲稿共36页在不同反射率条件下，透射光条纹的强度分布曲线结论：1、亮环的光强度为Ii；2、随反射率的增大，条纹变得越细锐，当反射率趋于1时，得到全暗背景上的极细锐的亮纹。9第9页，本讲稿共36页10第10页，本讲稿共36页11第11页，本讲稿共36页12第12页，本讲稿共36页二、法布里泊罗干涉仪（Fabry-Perot interferometer）（一）仪器结构（干涉仪和标准具etalon）13第13页，本讲稿共36页（二）用

3、作光谱线超精细结构的研究1、测量原理设光源中含有两条谱线：1和2，2=1+D则：标准具在中心附近对应的干涉级为m1和m2。对应于条纹的位移De于是有：14第14页，本讲稿共36页2.自由光谱的范围（能测量的最大波长差）2的(m-1)级条纹1的m级条纹自由光谱范围类似于卡尺的最大量程。15第15页，本讲稿共36页当1和2差值非常小的时，它们产生的干涉条纹将非常靠近，如果两个条纹合成的结果被视为一个条纹，则两个波长就不能被分辨。思路：波长能否被分辨，取决于条纹能否被分辨。瑞利判据瑞利判据：两个波长的亮条纹只有当它们合强度中央的极小值低于两边的极大值的0.81时，两个条纹才能被分开。3.分辨极限和分

4、辨本领（Resolvance of the interferometer）16第16页，本讲稿共36页G2G10.81Im在在G1点点epdpd-=mm2 ,221222141241222 22)()(sin,+=-p=d+pdFIFIImmiiFdd+FIFIIii)2(sin1)2(sin12212任意点的合成光强分布在在F点点17第17页，本讲稿共36页整理得：G2G10.81Im18第18页，本讲稿共36页cos2=1,2h=mG2G10.81Im19第19页，本讲稿共36页三、干涉滤色片（Interference filters）利用多光束干涉原理制成的一种从白光中过滤出波段较窄的单

5、色光的装置。干涉滤色片的结构保护玻璃片基G介质膜F银膜20第20页，本讲稿共36页1、滤色片的中心的波长（透射比最大的波长）干涉滤色片的参数21第21页，本讲稿共36页其中对应同一种波长，如=5.46x10-7m，m1，m2，m3对应的h1，h2，h3分别称为1，2，3级滤波片。22第22页，本讲稿共36页2、透射波长半宽度：透射比为峰值透射比一半时对应的波长差。已知，条纹的位相半宽度23第23页，本讲稿共36页3、峰值透过比24第24页，本讲稿共36页Interference filterColor filters are based either on absorption or on i

6、nterference.Both types are characterized by three parameters:the wavelength of maximum transmission or peak wavelength,max,in nm;the efficiency or peak transmittance,Tmax,in units of relative power transmitted;and the spectral purity or halfwidth,HW,that is the width of the passband at the level of

7、one-half the peak transmittance,in nm.25第25页，本讲稿共36页HWTmaxmax26第26页，本讲稿共36页ComplementarityInterference filters can also be made for reflection.Such filters are called dichroic mirrors;they reflect certain wavelengths and transmit others.Heat reflectors or hot mirrors reflect infrared(which on absorp

8、tion converts into heat)and transmit the visible;cold mirrors,used in movie projectors,transmit infrared and reflect the visible.27第27页，本讲稿共36页四、光学薄膜四、光学薄膜 利用物理或化学方法涂镀在玻璃表面或金属光滑表面上的透明介质膜，利于光波在薄膜中的反射、折射和干涉达到增反或增透的作用，还可以起到分光、滤光、调整振幅、位相和偏振态等作用。1、单层膜、单层膜 WnonnGh21设n0n面，t1，r1nnG面，t2，r2nn0面，t1，r1r1t1t2r2t

9、1r128第28页，本讲稿共36页反射光复振幅反射光复振幅 透射光复振幅透射光复振幅 式中式中 29第29页，本讲稿共36页Antireflection CoatingsPart of the light passing through a boundary is lost due to reflection.n1n2The reflectivity,at a boundary between two media and at normal incidence is 30第30页，本讲稿共36页Effective WayThe effective way is by interference,

10、applying a suitable coating to the surface.The reflections can be made cancel if the two reflected waves are out of phase by 180o,and in same amplitude.n2n1n0Thin film31第31页，本讲稿共36页n2n1n0Thin film32第32页，本讲稿共36页The thickness of the filmFor m=1n2n1n0Thin film33第33页，本讲稿共36页Homework(11-6)1.Determine the

11、 least separation of two spectrum lines,near 500nm,that can be resolved by an etalon that is 10mm long(deep)and has a reflectance of 90 percent.P245 19&2534第34页，本讲稿共36页Fabry&PerotMarie Paul Auguste Charles Fabry(1867-1945),French Physicist.While at the University of Marseilles,He taught medical stud

12、ents,later became director of the French Institute and professor of physics.Besides his work on electricity,spectroscopy,atmospheric ozone,and astrophysics,Fabry today is best known for the instrument he developed together with Jean Baptiste Gaspard Gustave Alfred Perot(1863-1925),which he referred to as“this interferometer whose name I have the honor to bear myself.”.35第35页，本讲稿共36页36第36页，本讲稿共36页