Toyota has extended warranty for certain models for this same problem, but not for Prius. My car has 117,000 miles and this problem has been going on for at least the last 25,000 miles (based upon orange warning triangle). According to dealer, problem is with rings (which is the recall for other Toyota cars). Also, according to dealer, this is a real problem for other Prius owners with 100,000+ miles.
Concave lenses in glasses correct this shortfall by spreading out the light before it reaches the eye, thereby enabling the person using them to see distant objects more clearly. Cameras. Camera manufacturers use combinations of concave and convex lenses to improve the quality of photographs.
A convex lens is thicker at the centre than at the edges. Convex lenses are thicker at the middle. Rays of light that pass through the lens are brought closer together (they converge). A convex lens is a converging lens. When parallel rays of light pass through a convex lens the refracted rays converge at one point called the principal focus. The distance between the principal focus and the centre of the lens is called the focal length.