Sunglasses, everybody knows the word. But does everybody know how they work and what components they consist of? I’m sure not. In this article I would like to tell you about complex creation of sunglasses, which seems simple at first sight. It’s two pieces of tinted glass or plastic and metal frame – you can say, but the process of creation is quite complex, more so than you think.
Sunglasses creators use a variety of technologies, such as tinting, polarization, use of photochromatic lenses, mirroring, scratch resistant, anti-reflective and ultra-violet coatings. Let’s delve a bit deeper into each point of sunglasses creation:
The colour of the tint determines the parts of the light spectrum that are absorbed by the lenses. Manufacturers use different colours to produce specific results.
– Grey tints are all-purpose tints, they reduce the amount of brightness and protect against glare. A good choice for driving and general use.
– Yellow tints-reduce the amount of blue light while allowing a larger percentage of other frequencies through. These tints eliminate blue part of the spectrum, but at the same time they make everything bright and sharp. That’s why glasses for snowboard or winter activities are usually yellow.
– Brown and amber-they have the added benefit of reducing glare in addition to UV rays. Generally used for both standard and prescription sunglasses.
– Green tints reduce glare and filter blue light.
This can be either natural or artificial. To understand this notion, imagine a lake, it is a good example of natural polarization. The reflected glare off the surface is the light that does not make it through the “filter” of the water, and is the reason why you often cannot see anything below the surface, even when the water is very clear. A polarized filter passes only the light that does not match its orientation. Polarized filters are most commonly made of a chemical film applied to a transparent plastic or glass surface.
These lenses have millions of molecules of substances, such as silver chloride or silver halide, embedded in them. When exposed to UV rays in sunlight, the molecules undergo a chemical process that causes them to change shape and the lenses darken.
Mirrored sunglasses are sunglasses with a reflective optical coating on the outside of the lenses to make them appear like small mirrors. The mirror coating decreases the amount of light passing through the tinted lens by anywhere from 10–60%, making it especially useful for conditions of sand, water, snow, and higher altitudes.
- Scratch-resistant coating
If glass is scratch resistant, plastic is not. Scratch-resistant films are made of materials such as diamond-like carbon and polycrystalline diamond, through the process of ionization this film is created on the lenses surface.
- Anti-reflective coating
The purpose of an anti-reflective coating is to reduce the reflection of glare on the lenses.
- Ultra-violet coating
A good UV coating on your sunglasses can eliminate UV radiation, which can cause sunburn of your retina, but prolonged exposure to UV radiation can cause even cancer of the eye. Before purchasing a pair of sunglasses check if your sunglasses filter out 100 percent of UV rays.
So, now you see that the process of sunglasses creation is rather complex. Give that a second thought next time you try on a trendy pair of sunnies.