Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10PolarizationBen KravitzThursday, September 10, 2009Outline•What polarization is•How it works•How it is useful to remote sensing2QuickTime™ and aGIF decompressorare needed to see this picture.OrientationRay direction remains the samehttp://www.colorado.edu/physics/2000/polarization/polarizationII.htmlPolarizationhttp://www.colorado.edu/physics/2000/polarization/images/typicalLIght.jpghttp://www.colorado.edu/physics/2000/polarization/images/polarizeLight.jpgTypical LightPolarized LightOrientation (again)Recall that, no matter which way the ray is oriented, we can break up the light ray vector into its horizontal and vertical componentsPolarizing Filtershttp://www.colorado.edu/physics/2000/polarization/polarizationII.htmlExampleshttp://www.colorado.edu/physics/2000/polarization/blocking_light.htmlhttp://www.colorado.edu/physics/2000/polarization/twisting_light.htmlUses of Polarization•Satellite transmission (multiple channels per frequency)•Minimize interference•Different responses by surfaces to different polarizationsPolarization and Remote SensingDifferent orientations are scattered in different wayshttp://www.ccrs.nrcan.gc.ca/glossary/index_e.php?id=2818Linear 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
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