| dioptric aberration | <microscopy> A lens defect in which image forming rays passing through the outer zones of the lens focus at a distance from the principal plane, different from that of the rays passing through the centre of the lens. The aberration caused by (near-paraxial) monochromatic light rays or electron beams passing through different radii of a lens not coming to the same focus. (05 Aug 1998) |
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| distortion aberration | The faulty formation of an image arising because the magnification of the peripheral part of an object is different from that of the central part when viewed through a lens. (05 Mar 2000) |
| optical aberration | Failure of rays from a point source to form a perfect image after traversing an optical system. (05 Mar 2000) |
| lateral aberration | In spherical aberration, the distance between paraxial focus of central rays on the optic axis. (05 Mar 2000) |
| longitudinal aberration | In spherical aberration, the distance separating the focus of paraxial and peripheral rays on the optic axis. (05 Mar 2000) |