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Polarization. Ben Kravitz Thursday, September 10, 2009. 2. Outline. What polarization is How it works How it is useful to remote sensing. Orientation. http://www.colorado.edu/physics/2000/polarization/polarizationII.html. Ray direction remains the same. Polarization.
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Polarization • Ben Kravitz • Thursday, September 10, 2009
2 Outline • What polarization is • How it works • How it is useful to remote sensing
Orientation http://www.colorado.edu/physics/2000/polarization/polarizationII.html Ray direction remains the same
Polarization http://www.colorado.edu/physics/2000/polarization/images/typicalLIght.jpg Polarized Light Typical Light http://www.colorado.edu/physics/2000/polarization/images/polarizeLight.jpg
Orientation (again) Recall that, no matter which way the ray is oriented, we can break up the light ray vector into its horizontal and vertical components
Polarizing Filters http://www.colorado.edu/physics/2000/polarization/polarizationII.html
Examples http://www.colorado.edu/physics/2000/polarization/blocking_light.html http://www.colorado.edu/physics/2000/polarization/twisting_light.html
Uses of Polarization • Satellite transmission (multiple channels per frequency) • Minimize interference • Different responses by surfaces to different polarizations
Polarization and Remote Sensing http://www.ccrs.nrcan.gc.ca/glossary/index_e.php?id=2818 Different orientations are scattered in different ways
Linear Polarization • Vertical Transmit, Vertical Receive (VV) - scattering due to surface capillary waves has a higher signal-to-noise ratio for this polarization, commonly used in oceanography for extracting surface wind speeds • Horizontal Transmit, Horizontal Receive (HH) - studying soil moisture (horizontally polarized waves pass through vegetation into the soil below), good for separating ice from water, good for ship detection • Horizontal Transmit, Vertical Receive (HV) - retrieval depends on the scattering mechanism, so good for differentiating different types of materials or structures • Vertical Transmit, Horizontal Receive (VH) - same as HV, but receiver noise is different, so this is averaged with HV to get a less noisy measurement