The relation of Cartesian and spherical polars is given in Spherical coordinate system. Spherical harmonics originates from solving Laplace's equation in the spherical domains. Eyeglass lenses that combine spherical and cylindrical correction are toric lenses. Examples include spherical and cylindrical symmetry. Aspheric lenses have at least one surface that is neither spherical nor cylindrical. This method is suitable for three imaging geometries&colon; planar, spherical, and cylindrical surfaces. A projection lens incorporating aspheric elements to correct for spherical aberration. Angular momentum operators usually occur when solving a problem with spherical symmetry in spherical coordinates. This point becomes center of the concentric spherical shells. Such mirrors may have surfaces that are spherical or parabolic. This effectively means that all planets are spherical or spheroidal. The coordinate systems are implemented in either spherical or rectangular coordinates. It may be implemented in spherical or rectangular coordinates. Refractors suffer from residual chromatic and spherical aberration. This is a simple, familiar example of spherical geometry.