#spherical aberration

• Aplanatic — Pertaining to or relating to aplanatism; an optical system (objective, lens, or mirror) that is rigorously corrected for both spherical aberration and coma aberration (Abbe's sine condition). This high-precision system allows the formation of a perfectly sharp and point-like image for an object located on the main optical axis, eliminating asymmetrical distortions of light beams.
• Aplanatism — The property or geometric condition of an optical system to simultaneously correct and eliminate both spherical aberration and coma aberration for a given point-like object. This physical phenomenon is achieved through strict compliance with Abbe's sine condition, ensuring the formation of exceptionally sharp and perfectly stigmatic images in the vicinity of the main optical axis.
• Aspheric — Not spherical; a geometric surface or optical component (lens, prism, mirror) whose profile deviates in a calculated manner from the shape of a perfect sphere. In optical engineering, aspherical surfaces are structurally designed to eliminate marginal spherical aberrations, allowing precise focusing of light rays into a single focal point and delivering superior image clarity with fewer lenses.