光学OPTICS教学课件：第一章光的电磁理论

1、光 学,OPTICS,第一章 光的电磁理论,第一章 光的电磁理论,第一节 电磁理论基础 第二节 光的能量和动量 第三节 光的辐射 第四节 光在介质中传播 第五节 经典理论的局限,Classical Optics at a First Glance,Waves aspect (Physical optics, wave optics,reflection,refraction,propagation,Particles aspect (Geometrical optics,polarization,interference, diffraction,Maxwells Equations,Guas

2、ss law （electric） Coulombs law,Generalized Amperes law Maxwells displacement current,Faradays induction law Maxwells induced electric field,Guasss law （magnetic） Biot-Savart law,第一节 电磁理论基础,Faradays Induction Law,第一节 电磁理论基础,Generalized Amperes Law,Displacement current,第一节 电磁理论基础,E-M Wave Equations in

3、 vacuum,The solutions of Maxwells equations are wave-like, with both E and B satisfying the wave equations above. Electromagnetic waves travel through vacuum at the speed of light c = (00)-1/2,第一节 电磁理论基础,E-M Waves in vacuum,第一节 电磁理论基础,c = (00)-1/2,A : amplitude : wavelength (spatial period) k : wave

4、 number (spatial frequency) T : period (temporal period) : angular frequency,Phase: the argument of the sine and cosine functions = kx t + 0,Temporal term,Spatial term,Initial phase,phase velocity,Rate of change of phase with time,Rate of change of phase with distance,第一节 电磁理论基础,E-M Waves in vacuum,

5、A periodic wave is referred to as harmonic wave. A sinusoidal wave with a single frequency is known as Simple Harmonic Wave (S.H.W.). A harmonic wave can be composed by a series of S.H.W. with different frequencies (Fourier series,sin(t) + 0.3sin(2t) + 0.2sin(4t) + 0.1sin(8t,第一节 电磁理论基础,E-M Waves in

6、vacuum,The Superposition Principle,If 1 and 2 are solutions of wave equation, then (a1 + b2) is also a solution,If simple harmonic waves are solutions of wave equation, then harmonic wave (linear combination of S.H.W.) is also a solution,第一节 电磁理论基础,E-M Waves in vacuum,The Complex Representation,第一节

7、电磁理论基础,E-M Waves in vacuum,Plane Waves,Wavefronts are the surfaces joining all points of equal phase. Any 3-D wave can be expressed as a combination of plane waves, each having a distinct amplitude and propagating direction,第一节 电磁理论基础,E-M Waves in vacuum,Spherical Waves,3-D wave equation,第一节 电磁理论基础,

8、E-M Waves in vacuum,Cylindrical Waves,When r is sufficiently large, kr 1,第一节 电磁理论基础,E-M Waves in vacuum,E-M Waves in vacuum,can be any continuous number,第一节 电磁理论基础,E-M Waves in vacuum,第一节 电磁理论基础,Transverse waves,Energy and Momentum,第二节 光的能量和动量,Energy density,Poynting vector,Irradiance: average amoun

9、t of energy per unit area per unit time,Energy and Momentum,Radiation pressure,Momentum,Momentum density,第二节 光的能量和动量,Energy and Momentum,第二节 光的能量和动量,第三节 光的辐射,Radiation of E-M Waves,Radiation source: non-uniformly moving charges,Linearly accelerating charges,Synchronton radiation,Electric dipole radi

10、ation,Radiation of E-M Waves,Radiation from atoms,第三节 光的辐射,Light in Bulk Matter,Dissipative absorption absorbing transfer disorder energy Non-resonant scattering absorbing atomic vibration re-emitting,第四节 光在介质中的传播,Dispersion Equation,Dispersion Absolute index of refraction is a function of frequency

11、 of light,第四节 光在介质中的传播,Orientational polarization Electronical polarization Ionic or atomic polarization,Dispersion Equation,第四节 光在介质中的传播,Dispersion Equation,For dense substances,Classical view: oscillator strength Quantum view: transition probability,第四节 光在介质中的传播,Dispersion (I,Anomalous dispersion,Normal dispersion,Absorption band,0, 0,n is constant,0,absorption,第四节 光在介质中的传播,Dispersion (II,n1 more transparent,第四节 光在介质中的传播,Maxwells wave theory,Light is transverse E-M waves Light carries en