Download Optical Properties

Chapter 19
Optical Properties
Group Four
Part One :
Colorful scenes from the opening ceremony of Beijing Olympic Games.
Concepts
Basic
concepts
Properties
Applications
Part Two :
Question:
What is the earliest mirror made of?
Part Two :
Question:
Why could bronze reflect light?
Concepts
Basic
concepts
Properties
Optical
properties of
metals
Applications
Part Three :
Experiment
Manmade Rainbow
Concepts
Basic
concepts
Properties
Optical
properties of
metals
Optical
properties of
nonmetals
Applications
Part Four :
News:
Head knocked on glass door.
Who is to be blamed?
※ Mr Yang himself?
※ The hotel?
※ The glass door?
Question::
Why glasses are
transparent?
Concepts
Basic
concepts
Properties
Optical
properties of
metals
Optical
properties of
nonmetals
Applications
Part Five :
Let’s take a break and see a video.
Question:
What is she
holding?
Concepts
Basic
concepts
Properties
Applications
Optical
properties of
metals
Laser
Optical
properties of
nonmetals
Part Six :
Example:
Widespread use of optical fiber.
Concepts
Basic
concepts
Properties
Applications
Optical
properties of
metals
Laser
Optical
properties of
nonmetals
Optical
fiber
Summary：
Concepts
Basic
concepts
Properties
Applications
Optical
properties of
metals
luminescence
photoconducti
vity
Laser
Optical
properties of
nonmetals
Optical fiber
Repoter:
Luo tian huan
Why could she see herself in the
Bronze Mirror ?
Optical Properties of Metals
Procedure
Basic
nature
The electron
energy band
schemes for
metals
Properties
Light
absorption
and
reflection
for metals
Performance
For visible
light,
Metals are
opaque
→
Perceived
colors
Application
Stimulation
for metals
to launch
X-rays as
the
invisible
radiation
Network Optimization Expert Team
The electron energy band schemes
for metals
•
•
solids at 0 K.
(a)The electron band structure found in metals such as copper, in which
there are available electron states above and adjacent to filled states, in the
same band.
(b) The electron band structure of metals such as magnesium（Mg）,
wherein there is an overlap of filled and empty outer bands.
Light Absorption for Metals
2011-12-2
Light Reflection for Metals
2011-12-2
Metals are opaque
The reflectivity :0.90 ~0.95;
Small fraction dissipated as heat.
Total absorption is within a very thin outer layer,
less than 0.1 μm
Perceived Colors
Determined by the wavelength distribution of the
radiation that is reflected and not absorbed.
2011-12-2
Copper
Aluminum
2011-12-2
Gold
Silver
The X-ray Rainbows
2011-12-2
The stimulation of X-ray
Professor Li
• When the moving electrons flow in high velocity
striking the anode materials such as
Chromium(Cr);Iron(Fe);Cobalt(Co);Nickel(Ni);Copper(Cu) and so forth,
X-rays will be radiated which is in high frequencies.
2011-12-2
Medical Examination
2011-12-2
Metal Defect Detection
2011-12-2
Scientific or technical literature
Science 12 February 1971:
Vol. 171 no. 3971 pp. 567-571
DOI: 10.1126/science.171.3971.567
Named：Alteration of Lunar Optical Properties: Age and Composition Effects
Science journal
Named：Muscles Made from Metal
Ray H. Baughman
Science 11 April 2003: 268-269. [DOI:10.1126/science.1082270]
IEEE JOURNALS
Named：The optical properties of metals
Ehrenreich, Henry;
Harvard University
Volume: 2 , Issue: 3
Digital Object Identifier: 10.1109/MSPEC.1965.5531773
Publication Year: 1965 , Page(s): 162 - 170
2011-12-2
Thank you ！
Optical properties
------- non-metals
Reporter mkk
1
Optical properties of non-metals
incident light
non-metals
transmitted light
reflected light
absorbed light
Classification: I = T + R + A
2
Part one
Transmitted light: Refraction
Definition : Light that is transmitted into the interior of transparent
materials experiences a decrease in velocity, and, as a result, is bent at
the interface; this phenomenon is termed refraction.
Index of refraction
phenomena:
n= c / v
The experiment
We have seen
3
Principle : electronic polarization
Part one
Result 1 :
--Light is slower in a material
--Light can be "bent"
Result 2 : Intensity of transmitted light decreases with
distance traveled (thick pieces less transparent!)
4
Reflection
Part two
Definition : When light radiation passes from one medium into
another having a different index of refraction, some of the light is
scattered at the interface between the two media even if both are
transparent.
Principle: electron transitions
The principle is similar to the reflection in the metals.
5
Part two
Do you know why optical instruments are always
coated with very thin layers of materials such as
magnesium fluoride (MgF2 ) at the reflecting surface ?
6
Part two
The reflectivity R (反射率)
index of refraction
of air is 1
The higher the index of refraction of the solid, the greater is
the reflectivity.
7
Part three
Nonmetals :Selected absorption
Condition : Absorption by electron
transition occurs if
Hν > Egap
8
Part three
A photon energy (in visible light)
1.8eV
red)
(
<
hν
<
(
3.1eV
purple)
• If Egap < 1.8eV, full absorption; color is
black (Si, GaAs)
• If Egap > 3.1eV, no absorption; colorless
(diamond)
• If Egap in between, partial absorption;
material has a color.
Xu xiao mei
9
Thank you !
10
Optical Fiber Communication
光纤通信
Jason (钱晨)
Prof. Charles Kao
 Father of Optical Fiber Communication
 Win The Nobel Prize in Physics 2009
 “For groundbreaking achievements concerning the transmission of light in fibers for optical communication.”
Optical Fiber Technology
 A Revolution
Optical Fiber Technology
 Optical Fibers V.S. Copper Wires 




Speed of Transmission Information Density Transmission Distance Error Rate Electromagnetic Interference Optical Fiber Communication System
 Optical Fiber——Heart of The System  Guide Light Pulses  Avoid Power Loss  Avoid Pulse Distortion Fiber Components  Core
 Let the signal pass through.
 Cladding
 Let the light rays travel within the core.
 Coating
 Protect core and cladding from damage.
Two Optical Fiber Designs
 Step-index Optical Fiber Design
 Graded-index Optical Fiber Design
Summary
 Optical Fiber Technology ——Improve speed of transmission, information density, transmission distance.
 Optical Fiber
——Heart of The Communication System.
 Fiber Components
——Core, Cladding, Coating.
 Two Optical Fiber Designs
——Step-index, Graded-index.
One Application of optical
phenomena——The magic
laser
Jin Wong
What’s your feeling
after watching the video?
• Excited?
• Amazed?
• Surprised? What laser is?
How can we get the laser?
• ——Let’s search the answer.
LASER
Light Amplification by
Stimulated Emission of
Radiation
Stimulated Emission
Light Amplification
(受激发射)
(光放大)
The process
of Stimulated
Emission
E1
E3 (10-8sec)
pro Key
ce
ss
E2 (10-3 sec)
(accumulation)
Light Amplification
The properties
of laser
monochromatic
directional
coherent
(单色的)
（定向的）
（相干的）
Star Wars in the real world!
Laser
Weapons
Powerful!
Laser Processing
How can laser
benefit our major?
Laser heat
treatment （激
Laser welding
光热处理）
diamond(激光焊
接金刚石)
Thank you for listening!
Our performance is going on~~
Optical properties
Color
Translucency
Opacity
By Xuxiaomei
RAPIDESIGN
1.The mechanism of color
The mechanism of color
Materials appear colored as a consequence of specific wavelength ranges of light that are selectively absorbed（选择性吸收）.
3.1eV
1.8eV
2.4eV
absorbed
Transmitted
（透射）
Reemitted
（重发射）
The fraction of the visible light having energies greater than Eg is selectively absorbed by valence band–conduction band electron transitions（跃迁）. absorbed
CdS,Eg=2.4eV
transmitted
reemitted
Sapphire （单晶氧化铝）
Ruby （sapphire added 0.5 ~2% of chromium oxide）
2.Specific impurities can change the color
3.Application of color
Glaze（上釉） is a thin shiny coating, or the act of applying the coating; it is used for decorating or protecting materials.
WINTER
Optic materials
Template
Transparency
（透明）
Translucency
（半透明）
single‐crystal
fully dense polycrystal
Opacity
（不透明）
polycrystal contain porosity
（气孔）
02
Pore（气孔）
Grain boundary
Grain boundary
A transmitted light beam is deflected（偏离） in direction and lead to scattering（散射）.
Hope you enjoy it!
THANK YOU
RAPIDESIGN
Chapter 19
Optical Properties
BASIC CONCEPTS
——Xu Hong
Contents
Electromagnetic Radiation
Light Interaction With Solids
Electronic Polarization
Electron Transitions
Contents
Electromagnetic Radiation
Light Interaction With Solids
Electronic Polarization
Electron Transitions
Electromagnetic
Radiation
Wavelike
Spectrum
Classical View
s
Quantized energy
Photon
Quantum-mechanical Views
wave
Perpendicular
Identical
spectrum
C=λν
λ
increase
ν
decrease
photon
What is a photon?
The unit of light
A kind of particle
A group or packet of energy
Light interactions with solids
•Incident light is either reflected, absorbed,
or transmitted: Io=IT+IA+IR
Light interactions with solids
•Optical classification of materials:
Electronic polarization
Phenomenon:
Causes:
•rapidly fluctuating electric field
•interaction between electric field and
electron cloud
Consequences: •Some of the radiation energy may
be absorbed
•Light waves are retarded in velocity
as they pass through the medium
Electron transitions
Two states: ground state and excited state
Two processes:
•Absorption
•Emission
Specific ΔE’s: ΔE =hν
Contents
Electromagnetic Radiation
Light Interaction With Solids
Electronic Polarization
Electron Transitions
Thank you !