| convex lens | A converging lens. Synonym: plus lens. (05 Mar 2000) |
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| double convex lens | A lens with both surfaces convex. Synonym: convexoconvex lens, double convex lens. (05 Mar 2000) |
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| convex | Applied to a surface that is evenly curved outward, the segment of a sphere. Origin: L. Convexus, vaulted, arched, convex, fr. Con-veho, to bring together (05 Mar 2000) |
| convex mirror | A spherical reflecting surface that constitutes a segment of the exterior of a sphere. (05 Mar 2000) |
| high convex | The segment of a sphere of short radius. (05 Mar 2000) |
| low convex | The segment of a sphere of long radius. (05 Mar 2000) |
| achromatic lens | A compound lens made of two or more lens's having different indices of refraction, so correlated as to minimise chromatic aberration. (05 Mar 2000) |
| acoustic lens | In ultrasonography, a lens used to focus or diverge a sound beam; may be simulated by electronic manipulation of signals. (05 Mar 2000) |
| anterior pole of lens | The central point on the anterior surface of the lens of the eye. Synonym: polus anterior lentis. (05 Mar 2000) |
| anterior surface of lens | The anterior surface of the lens of the eye. Synonym: facies anterior lentis. (05 Mar 2000) |
| aplanatic lens | A lens designed to correct spherical aberration and coma (q.v.). Synonym: periscopic meniscus. (05 Mar 2000) |
| apochromatic lens | A compound lens designed to correct both spherical and chromatic aberrations. (05 Mar 2000) |
| asphenc lens | <physics> A lens made aplanatic by grinding the outer zones to a greater radius than the inner zones. Aplanatic condensers can be made in this way. A simple aspheric lens is widely used as a lamp condenser because of its efficiency in converging light rays to one focal plane. (05 Aug 1998) |
| aspheric lens | A lens with a paraboloidal surface that eliminates spherical aberration. (05 Mar 2000) |
| astigmatic lens | A lens in which one of the surfaces is curved in one meridian and less curved in the opposite meridian; e.g., a teaspoon or a football. Synonym: astigmatic lens. (05 Mar 2000) |
| axis of lens | A line connecting the anterior and posterior poles of the lens of the eye. Synonym: axis lentis. (05 Mar 2000) |