Optics Modeling with Optica
Optics Modeling With Optica Project
A demonstration of spherical aberration: The spherical lens has a focal length of 35 and a width of 5 and has its center at 27.5. This should put the focus at 62.5.
When the ray height is small so that the ray is close to the optical axis you can see the focal spot is very close to 62.5. However, when the ray is far from the optical axis the spherical lens focuses the ray at shorter distances. So, the effect of spherical aberration is to spread the focal spot longitudinally as a function of ray height from the optical axis.