How Do Sunglasses Work?

Sure, it seems relatively simple.  Put tinted shades of plastic or glass, and suspend them on a wire frame to hang precariously, but not obtrusively, and securely at all times.  Not so simple anymore, is it? The pair of modern sunglasses is a relatively new invention in the world, and the culmination of several very different technological components, all fused into one easy and convenient package.

The main component of a pair of sunglasses is the pair of lenses that govern and reduce the amount of light that passes through them, and into the user’s eyes.  Different lenses may be any gamut of colors, from the darkest gray, brown, blue, green, red, and orange are seen, with gray and brown being the most common on lower priced pairs.  At the other end however, fashion designer sunglasses may be any shade and hue that the manufacture wants to produce, giving the purchaser a much greater variety.

The material of the lens is important in determining the use of the lens. Plastic lenses are used when cost or structural stresses outweigh the durability glass provides.  Polycarbonate lenses are used when the extra cost is offset by the additional weight reduction, UV protection and scratch resistance it has over plastic lenses.  But glass is the preferred material for lenses with ultimate optical qualities and scratch resistance.  Because of the active nature sunglasses are meant to be subjected to, polycarbonate is the most often chosen by sunglass manufactures. Although designer sunglasses such as those made by Cartier and Armani sometimes use glass over polycarbonate to provide the ultimate distortion-free vision for those wearing sunglasses more for fashion than practicality.

The lens will also be rated on numerous other properties to determine what activity is best suited to the sunglasses.  For instance, the purple hue on a hunter’s sunglasses is a  calculated choice to highlight the contrast of objects against a green background.  Yellow tint is useful for reducing the “blue haze” effect created by bright cloudless skies.  Important for all tints is its ability to reduce UV light in addition to visible light.  Lenses will be rated as blocking a certain percentage of light, the higher the value the better the protection and higher the cost.

To better aid the glasses in withstanding the rigors of everyday use, additional coatings or films, are added to strengthen the lens in a particular way.  Often these applications are stacked on top on one each other before being fused together as one “lens sandwich” so to speak.  Coverings can be used to counter reflective light or glare by adding a polarizing film.  Anti-scratch coatings aid its ability to withstand surface stresses.  When you also add in layers to produce the mirrored effect so popular of aviators and others, in addition to the anti reflective screens to help the polarizing film do its job and the end result is a technological rainbow of levels, all invisible to our eyes when we look through them.

With the lenses properly designed and manufactured, the final problem comes with putting them right where people need them, in front of their face.  Frames are designed to accomplish this seemingly easy task with a minimal amount of encumbrance.  Frames are supposed to do their job, not be too heavy to be uncomfortable, and always look good while they do it.  The frames of fashion designers Cartier, Armani and Bvlgari exemplify the fashion over function sunglasses meant to make a statement.  Frames from Oakley and Nike are loved by outdoor and sports aficionados for their combination of sleek style and rock solid performance.

Depending on the frame composition, the lenses may be housed rimmed, semi-rimmed, and rimless.  The advantages to each are the varying degrees of durability and style that each has, and the descision should be based on intended use.  Rimmed glasses are the most durable, but the extra material makes it that much more difficult to create a sleek and flowing profile.  It is great however for a bold retro look.  Semi-rimmed glasses are a hybrid between full rims and none at all.  Usually the top half of the glasses are attached with a rim that leaves the bottom half exposed.  The combination allows for a sleeker, cleaner look that compensates for the lower durability of the glasses.  Rimless is the territory of the purely fashion conscious wearer.  As the minimal setting on the glasses creates a bold look but weak resistance to stress.

With all the combinations available to manufacturers and designers, the customer today has an unparalleled selection of eye wear than ever before.  Consumers can pick the style and function that appeals to them, and can be sure that regardless of use, they can get a pair of sunglasses that will make the outdoors look better behind the shade.