aberrationsspherical

Spherical aberration is an optical phenomenon that occurs in lenses and mirrors with spherical surfaces. It arises because light rays that strike the outer edges of a spherical optic are refracted or reflected at a different angle than rays that strike the center. This difference in focal point leads to a blurred image, as the light does not converge to a single point. In lenses, rays passing through the periphery are typically focused closer to the lens than rays passing through the center. For mirrors, the effect is reversed, with peripheral rays focusing farther away. This aberration is a significant concern in optical instrument design, as it limits the sharpness and resolution of images. To mitigate spherical aberration, various techniques are employed. These include using aspheric (non-spherical) surfaces, employing multiple lens elements with specific shapes and refractive indices (achromatic or apochromatic designs), or using aperturing to block the peripheral rays. The severity of spherical aberration depends on the curvature of the optical surface and the refractive index of the material.