how sunglasses work - clear polycarbonate sheet
Sunglasses technology uses a variety of techniques to eliminate the light issues discussed in the previous section.
The following sections discuss all the different techniques currently used: the coloring color determines the spectral part that is absorbed by the lens.
Manufacturers use different colors to produce specific results.
Many manufacturers use a process called constant density to color the lens.
This is the oldest way to make sunglasses, and it involves a mixture of glass or polycarbonate in uniform color throughout the material.
When the lens is created, the hue is built directly into the lens.
Coloring can also be done by applying a light-colored coating
The molecules are adsorbed onto the transparent surface of polycarbonate.
The most common method for coloring polycarbonate lenses is to immerse the lenses in special liquids containing colored materials.
The color is slowly absorbed by plastic.
To make the color deeper, the lens just stays in the liquid for a longer time.
In the next few sections, we will introduce other sunglasses techniques.