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Is Invisibility Possible?

Ang GAO Ecole des mines de Saint-Etienne

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Outline

How does it work in science fiction?

Is it possible in science?

What is light?

How does light interact with objects?

Can we bend light?

Realization1 : metamaterials

Realization2 :transformation optics

Applications

Conclusion

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How does it work in science fiction?

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Is it possible in science?

David Smith

Duke University

Professor of electrical and computer engineering

“A true invisibility cloak IS possible within the laws of physics.”

Yes, it is possible!

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What is Light?

An electromagnetic wave, made up of different wavelengths.

380~780nm visible light

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How does light interact with objects?

Invisibility refers to an object which neither reflects nor absorbs light.Invisibility refers to an object which neither reflects nor absorbs light.

Reflection

Absorption

Transmission

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Can we bend light?

Yes - Refraction!

Refraction law : n1sinθ1=n2sinθ2

n: refractive index n>0

If n1>n2, then θ1<θ2; If n1<n2, then θ1>θ2; But that will not change the direction of ray.

Refraction law : n1sinθ1=n2sinθ2

n: refractive index n>0

If n1>n2, then θ1<θ2; If n1<n2, then θ1>θ2; But that will not change the direction of ray.

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Can we bend light as we want?

The cloaked zone is invisible!

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Archievement 1: metamaterials

Metamaterials have properties of NEGATIVE refractive index.Metamaterials contain tiny implants which can control the refractive index at every point in a material. This would enable light to bend in a path around an object

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Archievement 2: transformation optics

• Fourier Transformation• To change the coordinate system out of Cartesian

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Archievement 2: transformation optics

An experience in optical invisibility

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Applications

Cloaking military devices

Invisible soldiers, airplanes, tanks....

Diagnosing Disease

Improving medical imaging by cloaking internal organs and tissue

Computing faster

photonic computer chips replace of electronic computer chips

Harvesting Energy

A system using negative materials that will harvest light on the scale of a wavelength

Magic, art, fashion show

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Conclusion

Is invisibility possible? ----> Yes!

Is invisibility simple to accomplish? ---> No!

However, we have already realised the 2D invisibility, we created the

special material--->metamaterial which has a lot of applications.

Technology can change the world

We are on the way to the 3D invisibility...

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THANK YOU FOR YOUR ATTENTION!ANY QUESTIONS?