Scattering and Polarization

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Scattering and Polarization

• Application of Physical Optics

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Scattering of Light

• Rayleigh Scattering
• BLUE light (400nm) scattered more than RED
  (700nm)
• Light interacts with small air molecules
• BLUE sky is seen by Point A when looking toward
  the horizon (away from the sun).
• Light seen by Point B went through more
  atmosphere, more shorter wavelengths are
  scattered ? RED sky when looking toward the
  horizon (toward the sun).

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Polarization

• Polarized light Electric fields of waves vary
  along the same direction.

• Unpolarized light Electric fields vary along
  many directions.

E
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Polarization
Representations of light polarized on the
x-direction.
x
z
y
x
z
y
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Analyzing Polarized Light

• Determine how much light in different components

x-component y-component of the light
Polarizer only passes the x-component
Output is ONLY the light that is linearly
polarized in the x-direction
Light polarized at an angle ?
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Analyzing Polarized Light

• Two Perpendicular (Crossed) Polarizers

Polarizer Passes ONLY the y-component
Polarizer Passes ONLY the x-component
Unpolarized light in
No light passes through Crossed Polarizers