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Name: David
Status: other
Grade: other
Location: Outside U.S.
Country: Australia
Date: Fall 2012


Question:
When I use polarizing sunglasses most of the reflected light is removed. However in some circumstances such as on water or shiny asphalt, the reflection is still there and blue in colour. The glasses are neutral in tint and do not have a coloured reflective layer on the front. Why does the blue colour reflection get past the polarizer?

Replies:
David

Light is an electromagnetic (EM) wave (like a radio wave) that has electrical and magnetic fields oriented 90 degrees apart. The orientation of the electrical component of the EM wave defines its polarization as horizontal, vertical, or other orientations. Polarized sunglasses block out all light that is not the polarity of the polarized filter. This polarization process should not effect the color that you see, so there must be some blue tint in your lenses.

Sincere regards, Mike Stewart


David,

A polarized lens is usually a polycarbonate film that is stretched and coated with iodine, either a vapor or a solution. The lens is not neutral, it is tinted to the color of the iodine. Iodine reflects blue.

Hoping this helps! Peter E. Hughes, Ph.D. Milford, NH


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