Mirrorshades are sunglasses with a special reflective optical coating (called mirror coating or flash coating) on the outside of the lenses to make them appear like small mirrors, although the wearer usually sees things in a brown or grey tinted point of view. The mirror coating decreases the amount of light passing through the tinted lens by a further 10-60%, making it especially useful for conditions of sand, water, snow, and higher altitudes. From psychological angle of view, mirrorshades are effective in preventing eye contact.

In principle, mirrorshades act as one-way mirrors.

The color of the mirror coating is independent on the tint of the lenses. It is determined by the thickness and structure of the layer.

The simplest version of a mirror coating is a single layer of a deposited thin film of a suitable metal, usually prepared by ion beam deposition, sputtering or vapor deposition. However, this kind of coating is very prone to scratching, and degrades, especially in corrosive environment like salt water.

More modern reflective coatings usually have several alternating layers of specific thickness, made of dielectric materials and sometimes metals. The metal layer can be made from eg. titanium, nickel or chromium, or from an alloy like Nichrome or Inconel, and has thickness ranging from 0.5 to 9 nanometers. The dielectric layer comprises of a suitable oxide, eg. chromium oxide, silicon dioxide, or titanium dioxide; its thickness determines the reflective properties of the resulting dielectric mirror. The manufacturing process is similar to making anti-reflective coating, and mirror and antireflective coatings can be deposited in the same sequence of operations.

Characters in cyberpunk frequently wear mirrorshades. They are also popular among US police officers, especially Highway Patrolmen. Many characters in the movie series The Matrix exclusively wear mirrored sunglasses.

See also

• Bruce Sterling
• Cyberpunk 2020

Headgear | Ophthalmology | Mirrors