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  2. Lens (geometry) - Wikipedia

    en.wikipedia.org/wiki/Lens_(geometry)

    A lens contained between two circular arcs of radius R, and centers at O 1 and O 2. In 2-dimensional geometry, a lens is a convex region bounded by two circular arcs joined to each other at their endpoints. In order for this shape to be convex, both arcs must bow outwards (convex-convex). This shape can be formed as the intersection of two ...

  3. Lens - Wikipedia

    en.wikipedia.org/wiki/Lens

    A lens with one convex and one concave side is convex-concave or meniscus. Convex-concave lenses are most commonly used in corrective lenses, since the shape minimizes some aberrations. For a biconvex or plano-convex lens in a lower-index medium, a collimated beam of light passing through the lens converges to a spot (a focus) behind

  4. List of convexity topics - Wikipedia

    en.wikipedia.org/wiki/List_of_convexity_topics

    Contains three sub-branches: general convexity, polytopes and polyhedra, and discrete geometry. Convex hull (aka convex envelope) - the smallest convex set that contains a given set of points in Euclidean space. Convex lens - a lens in which one or two sides is curved or bowed outwards. Light passing through the lens is converged (or focused ...

  5. Geometrical optics - Wikipedia

    en.wikipedia.org/wiki/Geometrical_optics

    The focal length f is considered negative for concave lenses. Incoming parallel rays are focused by a convex lens into an inverted real image one focal length from the lens, on the far side of the lens. Incoming parallel rays are focused by a convex lens into an inverted real image one focal length from the lens, on the far side of the lens

  6. Focal length - Wikipedia

    en.wikipedia.org/wiki/Focal_length

    The focal point F and focal length f of a positive (convex) lens, a negative (concave) lens, a concave mirror, and a convex mirror. The focal length of an optical system is a measure of how strongly the system converges or diverges light; it is the inverse of the system's optical power.

  7. Aspheric lens - Wikipedia

    en.wikipedia.org/wiki/Aspheric_lens

    Like other lenses for vision correction, aspheric lenses can be categorized as convex or concave. Convex aspheric curvatures are used in many presbyopic vari-focal lenses to increase the optical power over part of the lens, aiding in near-pointed tasks such as reading. The reading portion is an aspheric "progressive add".

  8. Center of curvature - Wikipedia

    en.wikipedia.org/wiki/Center_of_curvature

    A concave mirror with light rays Center of curvature. In geometry, the center of curvature of a curve is a point located at a distance from the curve equal to the radius of curvature lying on the curve normal vector. It is the point at infinity if the curvature is zero. The osculating circle to the curve is centered at the centre of curvature.

  9. Precision glass moulding - Wikipedia

    en.wikipedia.org/wiki/Precision_glass_moulding

    “When the geometry of a lens extends beyond the volume range of a formed ball preform, a ground and polished ball preform is required. Used for lenses with positive power: biconvex, plano-convex, and meniscus: where the convex side is stronger, this geometry allows for molding of lenses with larger total volume.