How a Rear View Mirror Works

History

Rear view mirrors have not been around for as long as you might think. The first obscure mention of a rear view mirror is in the book "The Woman and the Car" in 1906, by Dorothy Levitt. Levitt proposed that women should carry hand-held mirrors while driving so that they can see behind them, if necessary. However, the first rear view mirror to be installed in a vehicle was in a race car at the first Indianapolis 500 race in 1911.

Viewing and Blind Spots

A rear view mirror is a normal mirror that is attached to the car's windshield. It can be maneuvered from side to side or up and down, depending on the height and orientation of the driver. When the driver looks into the mirror, he can see the road behind him. At the same time, the main rear view mirror leaves a blind spot of several meters directly behind the car on the either side. Therefore, side rear view mirrors can augment the effects of the main rear view mirror.

Reducing Glare

Side rear view mirrors can be problematic because they can shine the light from other cars' headlights directly into the driver's eyes. Therefore, a side rear view mirror is shaped like a wedge, so it has two surfaces: a shallow surface and a deep surface. The shallow surface is only slightly reflective, and the deep surface is completely reflective. During the day, the mirror is set so that all light hits the back part of the mirror. At night, however, the mirror is tilted so that the light from the headlights of other cars will bounce off of the shallow surface. This reduces headlight glare.