Cassegrain reflector
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A Cassegrain reflector is a combination of a primary concave mirror and a secondary convex mirror, often used in optical telescopes and radio antennas, the main characteristic being that the optical p
A Cassegrain radio antenna at GDSCC
Spherical aberration
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In optics, spherical aberration is a type of aberration found in optical systems that have elements with spherical surfaces. This phenomenon commonly affects lenses and curved mirrors, as these compon
Spherical aberration caused by a loupe. The center is sharp while the edges are blurred.
Longitudinal sections through a focused beam with negative (top row), zero (middle row), and positive spherical aberration (bottom row). The lens is to the left.
A point source as imaged by a system with negative (top row), zero (middle row), and positive spherical aberration (bottom row). The middle column shows the focused image, columns to the left show defocusing toward the inside, and columns to the right show defocusing toward the outside.