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A spherical lens has an aplanatic point (i.e., no spherical aberration) only at a lateral distance from the optical axis that equals the radius of the spherical surface divided by the index of refraction of the lens material. Spherical aberration makes the focus of telescopes and other instruments less than ideal. This is an important effect ...
A system fulfilling this condition and free from spherical aberration is called aplanatic (Greek a-, privative, plann, a wandering). This word was first used by Robert Blair to characterize a superior achromatism, and, subsequently, by many writers to denote freedom from spherical aberration as well. [8]
The idea of using the spherical aberration of a meniscus lens to correct the opposite aberration in a spherical objective dates back as far as W. F. Hamilton’s 1814 Hamiltonian telescope, in Colonel A. Mangin's 1876 Mangin mirror, and also appears in Ludwig Schupmann’s Schupmann medial telescope near the end of the 19th century.
These aberrations are of spherical and chromatic nature, that is, the spherical aberration coefficient C s and the chromatic aberration coefficient C c are always positive. [2] Scherzer solved the system of Laplace equations for electromagnetic potentials assuming the following conditions: electromagnetic fields are rotationally symmetric,
In spherical aberration (Bottom) peripheral rays are focused more tightly than central rays. There are numerous higher-order aberrations, of which only spherical aberration, coma and trefoil are of clinical interest. Spherical aberration is a term used clinically to refer to a fourth-order spherical aberrations. This term is not to be confused ...
where is the spherical aberration and is the magnification, both effectively being constants of the lens settings. One can then go on to note that the difference in refracted angle between an ideal ray and one which suffers from spherical aberration, is
It was created to correct the spherical aberration of the Hubble Space Telescope ' s primary mirror, which incorrectly focused light upon the Faint Object Camera (FOC), Faint Object Spectrograph (FOS), and Goddard High Resolution Spectrograph (GHRS) instruments. [1]
A three-mirror anastigmat is an anastigmat telescope built with three curved mirrors, enabling it to minimize all three main optical aberrations – spherical aberration, coma, and astigmatism. This is primarily used to enable wide fields of view, much larger than possible with telescopes with just one or two curved surfaces.