By David Boles
We’re all accustomed to mirrors in our bathrooms, on our cars and coating the Arena hotel. Their working principle is fairly simple. As light rays hits the surface, it bounces off symmetrically to the angle in which it came in:
|First developed commercially in the 1930s, retroreflective materials have gained wide prominence in our lives, though many of us don’t know what they are or how they work. Their fundamental theory of operation is that, like mirrors, they reflect light that bounces off of them, but instead of reflecting at the opposite angle, they reflect towards the source (retro – action directed backward). This can be accomplished a number of different ways. For instance, the first tape created with this property used tiny glass beads, covered in a traditional reflective coating. The combination of the lens created by the bead and the reflectivity, caused the tape to be retroreflective and return light in the direction that it came in (as shown on the right). It turns out that this ability is incredibly useful in a number of cases, particularly when you want something to be visible and the camera (or eyeball) has a source of light near it (such as headlights, camera flashes, etc.)|
Where is retroreflectance used?