Linear Polarization

							 Polarization

         Ben Kravitz
Thursday, September 10, 2009
                                       2



             Outline

• What polarization is
• How it works
• How it is useful to remote sensing
    Orientation

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  http://www.colorado.edu/physics/2000/polarization/polarizationII.html




Ray direction remains the
                                                    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/bloc
                    king_light.html


http://www.colorado.edu/physics/2000/polarization/twis
                    ting_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