LightLight

Questions ???Questions ??? What is light?What is light? Why can we see objects Why can we see objects

in the presence of light?in the presence of light? How fast does light How fast does light

travel?travel? What are the What are the

applications of light in applications of light in our daily life? our daily life?

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History of OpticsHistory of Optics

Geometrical Optics (study the behaviour of Geometrical Optics (study the behaviour of light using Geometry) by light using Geometry) by EuclidEuclid in Catoptrics, in Catoptrics, 300B.C.300B.C.

End of 17End of 17thth Century: Light as a wave to explain Century: Light as a wave to explain reflection and refraction, by reflection and refraction, by Christian HuygensChristian Huygens

1704: Light as moving particles to explain its 1704: Light as moving particles to explain its behaviour, by behaviour, by Issac NewtonIssac Newton

1864: Light as electromagnetic wave by 1864: Light as electromagnetic wave by MaxwellMaxwell

2020thth Century: Quantum theory (light as photon) Century: Quantum theory (light as photon)

How Fast does light travel ?How Fast does light travel ?

Early AttemptEarly AttemptGalileo GalileiGalileo Galilei proposed an “lantern” proposed an “lantern”

experiment in 1638experiment in 1638Experiment carried out by the Experiment carried out by the Accademia del Accademia del

Cimento of FlorenceCimento of Florence in 1667 in 1667 No Conclusive No Conclusive ResultResult

First estimate of light is made in 1676 by First estimate of light is made in 1676 by Ole Christensen RømerOle Christensen Rømer by studying the by studying the motion of Jupitor’s moon. motion of Jupitor’s moon.

Light travels at a speed of 300000000 Light travels at a speed of 300000000 m/s in vacuum.m/s in vacuum.

PhotonicsPhotonicsWhat is photonics?What is photonics?

Photonics is the practical application of light and Photonics is the practical application of light and optics.optics.

It integrates lasers, optics and electronics to It integrates lasers, optics and electronics to develop applications in industries develop applications in industries

Application: telecommunications, information Application: telecommunications, information technology, entertainment and displays, technology, entertainment and displays, lighting, consumer products, precision lighting, consumer products, precision manufacturing, biology and medicine, manufacturing, biology and medicine, environmental sensing, homeland security and environmental sensing, homeland security and defense, astronomy and aerospace, and defense, astronomy and aerospace, and research. research.

http://www.lasertechonline.org/Educator_course/overview.htmhttp://www.lasertechonline.org/Educator_course/overview.htm

Overview of PhotonicsOverview of Photonics

The term “photonics” is coined in The term “photonics” is coined in analogy with “electronics”.analogy with “electronics”.Electronics involves the control of Electronics involves the control of

electron charges.electron charges.Photonics involves the control of photons. Photonics involves the control of photons.

It reflects the growing tie between It reflects the growing tie between optics and electronics with the optics and electronics with the increasing role of electronics devices increasing role of electronics devices in optical systems.in optical systems.

Overview of photonicsOverview of photonics

Light emission Light emission Transmission Transmission Deflection: Reflection, Refraction, Deflection: Reflection, Refraction,

Diffraction, InterferenceDiffraction, InterferenceAmplification and detectionAmplification and detection

Major DevelopmentsMajor Developments

Invention of the Invention of the Laser in 1960sLaser in 1960s

Fabrication of low Fabrication of low loss optical fibersloss optical fibers

Introduction of Introduction of semiconductor semiconductor devicesdevices

Application of photonicsApplication of photonics

Information technology and Information technology and telecommunicationtelecommunication Information transportation, processing, Information transportation, processing,

storage etc.storage etc.Optical fiber for communications is being Optical fiber for communications is being

installed at the rate of 1000 meters per installed at the rate of 1000 meters per second.second.

To meet the needs of computing and To meet the needs of computing and communication in the next 10 to 20 years, communication in the next 10 to 20 years, many capacities have to hundredfold. many capacities have to hundredfold.

Application of photonicsApplication of photonics

Health care and life sciencesHealth care and life sciencesA wide variety of new therapies, e.g. A wide variety of new therapies, e.g.

laser heart surgerylaser heart surgeryNon-invasive diagnosis and monitoringNon-invasive diagnosis and monitoringNew biological research tools for New biological research tools for

visualisation, measurement, analysis visualisation, measurement, analysis and manipulation, e.g. use of laser in and manipulation, e.g. use of laser in DNA sequencing. DNA sequencing.

Application of PhotonicsApplication of Photonics

ManufacturingManufacturingLow-cost lasers and laser imaging system Low-cost lasers and laser imaging system Use of Optics in various industry such as Use of Optics in various industry such as

semiconductor, construction and chemical semiconductor, construction and chemical production, e.g. semiconductor chips are production, e.g. semiconductor chips are manufactured by optical lithography.manufactured by optical lithography.

Making optical equipment for manufacturing Making optical equipment for manufacturing itself is a $1 billion industry, and it supports itself is a $1 billion industry, and it supports the $200 billions electronics industry.the $200 billions electronics industry.

Application of photonicsApplication of photonics

Manufacturing of optical systems and Manufacturing of optical systems and componentscomponentsChanges in the design of optical Changes in the design of optical

systems and components to meet the systems and components to meet the needs in different industriesneeds in different industries

Better understanding of optical Better understanding of optical materials such as glass, polymers and materials such as glass, polymers and metals.metals.

Application of photonics Application of photonics

Optical sensing, lighting and energyOptical sensing, lighting and energyOptical sensor, revealing information Optical sensor, revealing information

that cannot be seen by human eyesthat cannot be seen by human eyesLighting system, reducing the electricity Lighting system, reducing the electricity

consumption consumption Solar energy (photovoltaic cell)Solar energy (photovoltaic cell)

Application of photonicsApplication of photonics

Military and surveillance Military and surveillance Satellite surveillanceSatellite surveillanceNight vision imagersNight vision imagersLasers for targeting and navigationLasers for targeting and navigation

The future of photonicsThe future of photonics

Extensive high-speed fiberoptic Extensive high-speed fiberoptic communications network around the communications network around the worldworld

New non-invasive way of health New non-invasive way of health monitoring, diagnosis and treatmentmonitoring, diagnosis and treatment

Highly efficient lighting system and Highly efficient lighting system and solar cellssolar cells

More efficient manufacturing control More efficient manufacturing control and processingand processing

What have you What have you learnt in this learnt in this

lesson?lesson?