ConclusionThin lenses are optical devices manufactured in ways that bend light in various different ways. Convex lenses focus distant images at a point on the side of the lens opposite from a light source. When the parallel rays of light pass through a convex lens, the refracted rays converge at a single point called the principal focus. Concave lenses focus distant objects so someone on the side of the lens opposite from which the incidence light is, sees the object as to be at a point behind the lens. When parallel rays of light pass through a concave lens, the refracted rays diverge, appearing as to come from one point called the principal focus.