光学性质基础
wave particle duality(by Einstein)
photoelectric effect:the emission of electrons or other free carriers when electromagnetic radiation, like light, hits a material. Electrons emitted in this manner can be called photoelectrons.
Plank equation
E=hv, h=6.626× 10-34 m2 kg / s
The de Broglie Relations
p=hv=hc/λ
Standing and Traveling waves
驻波（standing wave或stationary wave）为两个波长、周期、频率和波速皆相同的正弦波相向行进干涉而成的合成波。与行波不同，驻波的波形无法前进，因此无法传播能量，故名之。驻波最大值和最小值在某一固定点不动
行波（travelling wave）是指平面波在传输线上的一种传输状态，其幅度沿传播方向按指数规律变化，相位沿传输线按线性规律变化。
波是y=sinx,行波就是波要在走，y=sin(x-t)就可表示行波, 可以看到t=0时波是y=sinx, t=1时y=sin(x-1). 每一刻波都在往右走，这就是行波。y=sin(x+t)，也是行波，但是在往左走。
如果俩个完全一样，仅方向不一样的行波y=sin(x-t)和y=sin(x+t)相遇，公式变成y=2sinxcost,可以看到只要x=0，或者半波长整数倍的时候，y=0，代表这时不管t怎么变，这些点永远不动，这些点就是驻波的波节，在看除波节外的任一点，t=0时，y达到正幅值，t=1/4周期时，y=0,这时波是一条直线，所有值都是零，t=1/2周期时，y达到负幅值，所以y=2sinxcost就是驻波，波节不动，其余地方一直在震动。
？？？相速度和群速度？？？
some quiz
- Can gravity bend the light?(Yes, the star is not at the position we observe because of the sun)
- What is the princeple of fiber?(Total reflection)
- Are there any loss during the transpotation of fiber? If yes, where is the loss from?(yes, they from:a.any materials can absorb some light. b.the fiber is not all straight along the whole road. if there is a corner, 90 degree, which do not satisfy the prerequest of the total reflection. Herein, there will be some loss.)
- What are the conditions for total reflection to occur?(a.from n larger medium to n small medium, n is refraction index b. staify critical angle)
- What’s the difference between mechanical wave and electromagnetic wave?(transportation medium)
- Waht is the wave number?(k=2π/λ)
words
Isotropic:各向同性
Sodium:钠
copper:铜
Zinc:锌
Prism:棱镜
reflection:反射
refraction:折射