Refraction

When the direction of light is changed by lenses it occurs by a process known as refraction. Here, five laser beams are refracted in different ways.

Five parallel laser beams illuminate a white disk. By turning the disk, it is possible to make the light beams pass through lenses of different shapes and to see what happens to the beams. The refraction of the light as it passes through, for example, glass is a result of, among other things, that the speed of light is lower in glass than in air. Refraction takes place just at the transition between the different materials, the pathway of the light within the lens is straight.