Lenses have different shapes and different parameter requirements. Nowadays, spherical lenses and aspherical lenses are often seen. Let’s take a look at the difference between high-precision ground spherical lenses and aspherical lenses today.
Spherical lens refers to the constant curvature from the center to the edge of the lens, while aspherical lens has the curvature that continuously changes from the center to the edge.
The "curvature of the spherical surface" of a spherical lens is constant, that is, both the front and back surfaces of the lens are part of the spherical surface. Each surface can be convex (convex outward from the lens), concave (concave into the lens), or "flat" (flat). The line connecting the spherical center points of the front and back surfaces of the lens is called the optical axis of the lens. In almost all situations, the optical axis of the lens passes through the physical center of the lens. The radius of curvature of the aspheric lens changes with the central axis, which has a better radius of curvature and can maintain good aberration correction. The aspherical lens is used to replace the spherical lens. The most significant advantage is that it can correct the spherical aberration caused by the spherical lens in the collimation and focusing system. By adjusting the surface constant and the aspheric coefficient, the aspherical lens can eliminate the spherical aberration to the greatest extent. The aspherical lens basically eliminates the spherical aberration caused by the spherical lens. At present, the main processes of aspherical lens are: precision glass molding, precision polishing molding, hybrid molding, and injection molding.