interference diffraction Huygens principle interference Fig 35 8

interference(干涉) diffraction(繞射)

• Huygens principle 雙狹縫干涉(interference) 單狹縫 Fig 35 -8 • 1801年，Young干涉實驗 • 遠場光學vs. 近場光學

繞射diffraction 單狹縫

干涉(interference) & 繞射(diffraction) Fig. 36 -10 亮紋或暗紋？ Fig. 36 -5 亮紋或暗紋？

干涉+繞射 • 範例 (Problem 31) • 例題 36 -5 (Fig. 36 -14) • Check point 5 • Question 9 Fig. 36 -3

布拉格繞射實驗 例：Ch 36 Problem 58, 57 例：Ch 36 Problem 60, 61, 63 例：Ch 36 Problem 59

Ch 36 Problem 58 An x-ray beam of a certain wavelength is incident on a Na. Cl crystal, at 30. 0 o to a certain family of reflecting planes of spacing 39. 8 pm. If the reflection from those planes is of the first order, what is the wavelength of the x rays?

Ch 36 Problem 57 Figure 36 -44 is a graph of intensity versus angular positionθ for the diffraction of an x-ray beam by a crystal. The beam consists of two wavelengths, and the spacing between the reflecting planes is 0. 94 nm. What are the (a) shorter and (b) longer wavelengths in the beam? 0. 75 1. 15 1. 55

Ch 36 Problem 60 In Fig. 36 -45, first-orderreflection from the reflection planes shown occurs when an x-ray beam of wavelength 0. 260 nm makes an angle 63. 80 with the top face of the crystal. What is the unit cell size a 0? 63. 80 m=1 Θ=63. 8 o-45 o=18. 8 o Answer: a 0=0. 57 nm Homework：畫出反射光

Ch 36 Problem 63 (晶體旋轉) In Fig. 36 -46, let a beam of x rays of wavelength 0. 125 nm be incident on an Na. Cl crystal at angleθ= 45. 0 o to the top face of the crystal and a family of reflecting planes. Let the reflecting planes have separation d=0. 252 nm. The crystal is turned through angle ψ around an axis perpendicular to the plane of the page until these reflecting planes give diffraction maxima. What are the (a) smaller and (b) larger value of ψ if the crystal is turned clockwise and the (c) smaller and (d) larger value of ψ if it is turned counterclockwise?

晶體面 Problem 61

色散(chromatic dispersion)

補充題：光纖 (fiber) 類題： Ch 33 Problem 59

反射產生之偏振：布魯斯特角 (Brewster angle θB) • 反射光與折射光互相垂直：θr + θB=90 o • 折射定律：n 1 sinθB= n 2 sinθr 補充例題 We wish to use a glass plate with index of refraction n=1. 57 to polarize light in air. (a)At what angle of incidence is the light reflected by the glass fully polarized? θB= tan -1 n = tan -1 1. 57 = 57. 5 o (b) What is the corresponding angle of refraction? θr = 90 o -θB = 90 o - 57. 5 o= 32. 5 o Home Work： Problem 65, 87 (Ch 33)