湖北大学：《大学物理》第十七章（17-5） Lens透镜

4. Michelson's interferometere The path of a particular ray M Lens透镜 G1 half-silvered mirror半镀银镜 2 compensation mirror补偿镜 1、M2 reflecting mirror)射镜E E- eyes and telescope眼和望远镜

S L—lens透镜 G1—half-silvered mirror半镀银镜 G2—compensation mirror补偿镜 M1、 M2 reflecting mirror反射镜 4.Michelson’s Interferometer The path of a particular ray： E—eyes and telescope眼和望远镜 M1 M2 G1 G2 L E M’1

Discuss When m has been moved A/2 one -half a wavelength optical path difference is changed by one 2 wavelength 当视场中看到N个 M 条纹移过时,M E 平移的距离为: d= N 2 ①测量微小长度的变化; 迈克尔逊干涉仪的应用:②测量光波长

E S M1 M2 G1 G2 L When M2 has been moved one –half a wavelength, optical path difference is changed by one wavelength. Discuss：  / 2 当视场中看到N个 条纹移过时，M2 平移的距离为： 2  d = N 迈克尔逊干涉仪的应用： 测量微小长度的变化； 测量光波长

迈克尔逊干涉1960年国际会议规定: 1m=1650763.73 1983国际17届计量 会议规定: 1m=C×1/299792458s C为光速 E 历史上迈克尔逊曾用此干 涉仪测定红隔线的波长: 几.=64384696A 15C1m的干燥空气中的 1927年国际会议规定: ure 6-16. Interferometer used by Michelson and Morley in their measurements of y of light. A sandstone table boldin mirrors is fixed to mercury. The series of mirrors serves to lengthen the total path of 1m=1553164.13 ered plate is placed along one path to compensate for the fact that th rference fringes. Drawing courtesy of Scientific Amercan)

历史上迈克尔逊曾用此干 涉仪测定红隔线的波长：  A Cd  = 6438.4696 150C.1atm的干燥空气中 1927年国际会议规定： Cd 1m =1553164.13 Kr 1m =1650763.73 1983年国际17届计量 会议规定： 1m =C1/ 299792458s C为光速 1960年国际会议规定：

Example: Two 20cm glass tubes are placed in the two arms of a Michelsons interferometer respectively. One is vacuum and the other is filled up with Ar gas. Considering the light from extended source S(2=5460A) falls on the interferometer. If Ar gas is drawn off. a shift of 205 fringes occurs. Find the refractive index of Ar gas Solve M 2(n-1)=△ n-1=△2/2lS GG 2 205×5.46×10 2×0.20 =0.28×10 E n=1.00028

Example：Two 20cm glass tubes are placed in the two arms of a Michelson’s interferometer respectively. One is vacuum and the other is filled up with Ar gas. Considering the light from extended source S（=5460A）falls on the interferometer. If Ar gas is drawn off , a shift of 205 fringes occurs. Find the refractive index of Ar gas. E S M1 M2 G1 G2 L 2(n −1)l = k n−1= k / 2l 2 0.20 205 5.46 10 7    = − Solve： 3 0.28 10− =  n =1.00028 l l