Polarization

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Polarization
PHYSICS 1
Natural Radiation

• Somnath Bharadwaj and Pratik Khastgir,
  Department of Physics and Meteorology, IIT
  Kharagpur, 721 302 India
• http//www.cts.iitkgp.ernet.in/phy1/

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Linear Polarizer
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Malluss Law
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Producing Linear Polarization

• Dichroism or selective absorption
• Scattering
• Reflection
• Birefringence or double vision

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Dichroism
Wire-mesh polarizer
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Dichroic Crystals
Tourmaline coloured crystal
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Polaroid H sheet

• Possibly most commonly used polarizer
• Inventor E H Land in 1938
• Polyvinyl alcohol sheet heated and stretched
• Dipped in iodine rich ink
• Iodine chains along direction of stretching
• Acts like a wire mesh

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Scattering
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Sky light is polarized
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Reflection
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Brewsters Law
Brewsters angle
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Birefringence

• Occurs in anisotropic crystals
• Refractive Index ne when E along x axis
• Refractive Index no when E perp. to x axis
• Optic axis along x
• Uniaxial Crystal

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Birefringence
positive
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Wollaston Prism
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Quarter Wave Plate
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Linear to Circular
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Partially Polarized Light
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Degree of Polarization