Three important lights related to sunglasses.

Three important lights related to sunglasses:

Direct light-Direct light is the light that hits your eyes directly from a light source (such as the sun).

Too much direct light will make the details of the surrounding environment appear blurred, and it will also make it difficult for you to focus.

Reflected light-reflected light is often in the form of glare.

Reflected light is the light reflected from a reflective object back to the eye.

Like direct light, strong reflected light makes it difficult for people to perceive details or look directly at an object.

Snow, water, glass and white sand are all good reflective surfaces.

Diffuse light-Diffuse light is light scattered in many directions after being bounced, so it seems that this kind of light does not have a specific light source.

A typical example of diffuse light is the glow above a big city.

It is difficult to determine a single light source for it.

When there is no direct light source, we can still see things, which is the credit of diffused light.

High-quality sunglasses can eliminate ultraviolet rays in the spectrum, reduce direct light, make people feel comfortable, and also eliminate or reduce reflected light (depending on the reflective surface).

An interesting property of light is polarization.

When reflected from certain surfaces, such as water, the light will be polarized.

Due to the polarization characteristics of reflected light, polarized sunglasses can eliminate light reflected from water or similar reflective surfaces.