Understanding polarized light.

Learn about polarized light.

Light waves from artificial light sources such as the sun and even light bulbs vibrate and propagate in all directions.

Whether the light is propagated, reflected, diverged or refracted, when the light is vibrating in one or more plane directions, we say that the light is polarized.

The polarization process can be naturally occurring or artificially excited.

The glare you see every time you look at the lake is an example of natural polarization.

The glare reflected from the lake surface is the light that fails to pass through the "filter" of the lake water, which is why it is impossible to see objects under the lake surface even if the lake water is very clear.

Polarizing filters are generally made by plating a chemical film on a transparent plastic or glass surface.

Normally, the molecules in the compound used are naturally arranged parallel to each other.

When they are evenly coated on the lens, these molecules form tiny lenses that can absorb all the light in the same direction as they are arranged.

Most of the glare that forces you to wear sunglasses comes from horizontal surfaces such as water and highways.

When light reaches a surface, the reflected light will be polarized in the same direction as the angle of the surface.

Therefore, a highly reflective horizontal surface, such as a lake surface, can produce a large amount of horizontally polarized light.

Therefore, the polarized lenses of sunglasses are fixed at an angle so that only vertically polarized light can pass through the lenses.

You can observe this principle by the following method: wear polarized sunglasses, and then observe a horizontal surface, such as the hood of a car.

Slowly tilt your head to the left or right.

You will find that the glare from this surface will become brighter as you adjust the angle of sight.

Sunglasses or prescription glasses that darken when the mirror surface of the sunglasses are exposed to sunlight are called color-changing glasses.

The principle of the color-changing lens mainly relies on a special chemical reaction of ultraviolet light.