| equator of lens | The periphery of the lens lying between the two layers of the ciliary zonule. Synonym: equator lentis. (05 Mar 2000) |
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| equator | 1. <geography> The imaginary great circle on the earth's surface, everywhere equally distant from the two poles, and dividing the earth's surface into two hemispheres. 2. <astronomy> The great circle of the celestial sphere, coincident with the plane of the earth's equator; so called because when the sun is in it, the days and nights are of equal length; hence called also the equinoctial, and on maps, globes, etc, the equinoctial line. 3. <astronomy> Equator of the sun or of a planet, the great circle whose plane passes through through the center of the body, and is perpendicular to its axis of revolution. Origin: L. Aequator one who equalizes: cf. F. Equateur equator. See Equate. Source: Websters Dictionary (01 Mar 1998) |
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| equator bulbi oculi | An imaginary line encircling the globe of the eye equidistant from the anterior and posterior poles. Synonym: equator bulbi oculi. (05 Mar 2000) |
| equator lentis | The periphery of the lens lying between the two layers of the ciliary zonule. Synonym: equator lentis. (05 Mar 2000) |
| equator of eyeball | An imaginary line encircling the globe of the eye equidistant from the anterior and posterior poles. Synonym: equator bulbi oculi. (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) |
| back lens | <physics> In any compound lens (a lens system composed of more than one lens element), the last lens through which the light passes is called the back lens. It may be a single simple lens, a doublet, or triplet. See: front lens (05 Aug 1998) |