1. Scattering and Polarization
Application of Physical Optics
Imaging Science Fundamentals
Chester F. Carlson Center for Imaging Science

2. 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). A B
In the DRAWING:
Point A: The sky appears blue due to scattering. The scattered light from the other ray is linearly polarized.
Point B: When this person looks toward the sun the sky appears reddish because the most of the shorter wavelength light has already been scattered away.
Imaging Science Fundamentals
Chester F. Carlson Center for Imaging Science

3. Polarization
Polarized light: Electric fields of waves vary along the same direction.
Unpolarized light: Electric fields vary along many directions. E E E E E E
Imaging Science Fundamentals
Chester F. Carlson Center for Imaging Science

4. Representations of light polarized on the x-direction.
Polarization
Representations of light polarized on the x-direction. x z y x z y
Imaging Science Fundamentals
Chester F. Carlson Center for Imaging Science

5. “Analyzing” Polarized Light
Determine how much light in different components:
x-component
&
y-component
of the light
Polarizer;
only passes the x-component
Light polarized at an angle 
Output is ONLY the light that is linearly polarized in the x-direction
Imaging Science Fundamentals
Chester F. Carlson Center for Imaging Science

6. 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
Imaging Science Fundamentals
Chester F. Carlson Center for Imaging Science