In these studies, the reported surfaces are still macroscopically flat, with the feature size at the scale of microns or nanometres. In nature, many plant surfaces have convex or concave ...

Biconvex lenses also known as double convex lenses are simple optical lenses with two convex spherical surfaces, surfaces which bulge out ... for a wide range of beam-focusing applications. The Figure ...

To control light, curved lenses are used today, which are often made of glass that is either concave or convex ... are placed in patterns on a flat surface and become receivers for light.