In 2-dimensional
geometry, a
lens is a
convex set bounded by two
circular arcs joined to each other at their endpoints. In order for this shape to be convex, both arcs must bow outwards (convex-convex). This shape can be formed as the
intersection of two
circular disks. It can also be formed as the union of two
circular segments (regions between the
chord of a circle and the circle itself), joined along a common chord.