Is a spherical lens spherical?
The English name of spherical lens is spherical lens. Generally speaking, a spherical lens refers to a lens in which at least one surface of the lens is spherical. On this sphere, each meridian is curved, and the bending angle is the same. Both concave lens and convex lens are spherical lens. The concave lens is also called negative spherical lens, and the convex lens is called positive spherical lens. Convex lens is a lens with thick middle and thin edge.
Convex lens can gather light, so convex lens is also called convergent lens. However, manufacturer of spherical lens when the light parallel to the main optical axis passes through the convex lens, they converge at a special point on the main optical axis, which we will also call the focus of the convex lens, represented by F. Since the convex lens has a real focus on both sides of the mirror, the convex lens has two real focus. A concave lens is a lens with a thin middle and a thick edge.
