|physics See also aberration a defect of optical systems that arises when light striking a mirror or lens near its edge is focused at different points on the axis to the light striking near the centre. The effect occurs when the mirror or lens has spherical surfaces|
spherical aberration n.
A blurred image that occurs when light from the margin of a lens or mirror with a spherical surface comes to a shorter focus than light from the central portion. Also called dioptric aberration.