Description

It is a lens that one surface is plane with squareness shape, another surface is concave with cylindrical shape, its role is making beam converging or diverging on a plane, and that beam does’t work for the perpendicular plane(cylindrical axis) with it. So a cylindrical lens can turn a transmitted plane wave into a cylincrical wave, or turn an original cylindrical wave into a plane wave or spherical wave, such a kind of lens can correct ocular astigmation.