There are many kinds of sunglasses, they have different function. Today, we will learn some knowledge about polarized sunglasses. We all know, this kind of sunglasses usually use for outdoor sport, for example, fishing. When the sun shines on the water or any other reflective surface, the reflected light becomes polarized. This means that most, although not all of the light waves move in one plane. You see, normal light moves in many planes and polarized lenses allow only light in one plane to pass through the lens. Therefore much of the glare is eliminated.

Polarized lenses can not eliminate all reflected light. As we said before, polarized sun glasses eliminate selective parts of the reflected light, thus reducing glare. Although light from the sun is not polarized, it can be separated into two polarized components that are reflected and transmitted in different amounts by the surface of the water. In most cases more of the horizontal component will be reflected than the vertical component, thus partially polarizing the reflected light. In order to help eliminate the glare a lens that is vertically polarized is used. The height of the sun also affects the degree of polarization.

The polarized sunglasses worn by fishermen have polarized filters to help block the light reflected by the waters surface allowing them to be able to see under the waters surface.