The lens is divided into convex lens and concave lens. Attachment: convex lens, Manufacturer of spherical lens thick in the middle, thin on both sides, concave lens, thick on both sides and thin in the middle. Both convex lens and concave lens are composed of a spherical surface (to be discussed later) or a part of two spherical surfaces (to touch your magnifying glass). The first answer is that the 2D lens is cylindrical lens,Manufacturer of spherical lens to be discussed later. Looking down, the wonderful continues. We imagine two spheres in our head. How can they be put together? Think about it and give four figures to understand. Do you understand? I don't understand. Then, Manufacturer of spherical lenscylindrical lens and spherical lens are similar, but the thickness is the same.
