Polarizing+Filters


 * Polarizing Filters **

Light, like all electromagnetic radiation, is made up of three components all perpendicular to one another – an electric field, a magnetic field, and velocity. Polarizing filters or disks block a specific dimension of light to enhance image quality and reduce glare. During fabrication, molecules of EMR-blocking material are stretched and aligned in a certain direction, be it vertical or horizontal. As such, only the velocity and one of the two fields may pass through a given filter, because the third dimension simply will not fit, as illustrated by the image below. If two polarizing filters are placed so that their slits are at 90 degrees to each other, no light will be able to pass through, as both the electric and magnetic fields will be blocked.

This technology is commonly used in the manufacturing of sunglasses. Sunglasses use polarized disks that have molecules aligned horizontally, or parallel to the ground. This allows them to block the unnecessary vertically polarized light that may reflect off the ground or other objects, and prevents the annoyance of glare in addition to producing a better image. Polarized disks are also common in photography for the same reason (the eradication of glare).

For further information, consult @http://www.colorado.edu/physics/2000/polarization/polarizationII.html. It has comprehensive notes on polarization and polarizing filters, as well as great applets.

References: @http://www.physicsclassroom.com/class/light/u12l1e.cfm @http://www.flickr.com/photos/physicsclassroom/galleries/72157625101670351/

Wiki by Emily Holden