Aspheric lenses can improve image quality and correct imaging problems typically associated with spherical lenses. The original work and functions of aspherical lenses are mainly reflected in the following aspects
1. Ball deviation
In a spherical lens, light is focused at different distances (depending on its position relative to the edge of the lens), which can cause blurring and peripheral distortion. This phenomenon is called spherical aberration.
Aspheric lenses can reduce or eliminate this problem due to their unique design (with shallower surface curvature angles). When light enters an aspherical lens, regardless of whether it enters or not, it will focus on a point, resulting in a clearer and sharper image.
2. Distortion
When spherical mirrors magnify or shrink images, they distort and bend the lines viewed through them. Due to the low edge power of aspherical lenses, the risk of pillow shaped distortion of positive lenses and tube distortion of negative lenses can be reduced or eliminated.
3. Edge astigmatism
Edge astigmatism refers to the unnecessary Power gain in spherical and cylindrical lenses when observing something from the optical center. It helps to create blurry images. Aspheric lenses avoid this by reducing the Power gain along the edge of the lens.