the basic theories of light

8/12/2019 The Basic Theories of Light

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Theories and asicConcept of Light

JAN FERN H

BS Electronics and Communications

Optoelectronics Engr. Joybelle b


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a : something that makes vis

b : the sensation aroused by stimulation of the visua

c : electromagnetic radiation of any wavetravels; such radiation that is visible to the


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It is a special ki

electromagnetic en


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Sources of LightIncandescent lightlight prodby heating an object until it glo


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Fluorescent Light Light produced by electron bombardm

gas moleculesPhosphors absorb photons that are creawhen mercury gas gets zapped with eleThe phosphors glow & produce light.


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Optoelectronicsvs.photonics Vs. Electro

Photonics - the technology

generating and harnessing liwhose quantum unit is the pho


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Optoelectronics - to a deviceresponds to optical power, emmodifies optical radiation or u

optical radiation for its internoperation.


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Electro-Optics - to a device that respoptical power, emits or modifies op

radiation or utilizes optical radiationinternal operation or any devicefunctions as an electrical-to-optic

optical-to electrical transducer.


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History of Optics Early (ca 1200 BCE)Bible Passage of Exod

The Use of Mirrors


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History of OpticsIBN AL-HAYTHAM (965 in Basra - c. 1039 in Ca

Father of Optics


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History of optics

Newton (17thCentury)asserted that light was formvery tiny corpuscles (particles).


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History of OpticsHuygens (17thCentury)

that light was a wave, basing this affon its undulatory (wave like) characconcept of etherwas introduced.


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History of Optics

Michelson and MorleysEther does not exist.Speed of light is constant.


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History of Optics

Planck and EinsteinUndulatory Theory is not truCorpuscle Theory - Photon


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General Characte

Speed = 2.99 x 10 8m/s in a vacuum state.

0.03 % lesser in air and 30.0 % slower

It travels in a straight line at fixed speed, one energy from one place to anot

Can be represented with magnitude anddirection.

Wave-Particle Duality


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TRIVIA

Detection and measurement o

light energy is called radiomet


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The Dual NatDeveloped models to

effects of ligh

Light can behave as a wave

Light can behave like a discreparticle (quantum)

The Concept of a Photon


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The Concept of PhotonThe particle-like of nature of l

modelled with photons.Based on Sir Albert Einstei

Photoelectric effect


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The Concept of PhotonPhoton has no mass and no chais a carrier of electromagnetic e

and interacts with other dparticles like electrons, atommolecules.


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The Concept of Photon

A beam of lightis modelled asa stream of

photons.

Each Photona well-deenergy th

dependent uwavelength


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The Concept of Photon The Photon Energy can be compute

=

Where: E = Photon Energy (Joules)h = Plancks Constant = 6.625 x 10 -34(

C = speed of light (m/s)= wavelength (m)


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The Dual NatDeveloped models to

effects of ligh

Light can behave as a wave

The Concept of a PhotoThe Concept of Waves


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The Wave ModelLight was first described as a w

due to its behaviour.


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The Wave ModelUsed to describe fine-scale esuch as interference and diffra

that occur when light passes thsmall openings or by sharp ed


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The Wave ModelUsed to describe fine-scale esuch as interference and diffra

that occur when light passes thsmall openings or by sharp ed


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The Wave ModelThe propagation of light or electrom

energy can be described as a travwave in motion. The wave moves ewithout moving massfrom one pl

another at a speed independent intensity or wavelength.


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The Wave ModelThis wave nature of light is theof physical optics and describ

interaction of light with med


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Light as a WAVE


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The Wave ModelThe wave carries light energy withamount of energy that flows per s

across a unit area perpendiculardirection of travel is called thirradiance (flux density) of the w


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The Duality of Light

Metal Plate


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WAVE MODEL OF LIGExplains most properties of light

PARTICLE THEORY OF LPhotoelectric Effect Photons of light produce fr

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the basic theories of light

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