| projection lens | <microscopy> The final lens in the electron microscope. The lens focuses the electrons onto a fluorescent screen to produce the visible image. (05 Aug 1998) |
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| slab-off lens | A spectacle lens with a base-up prism below; used in unequal myopia to equalise image displacement when reading. (05 Mar 2000) |
| spherical lens | A lens in which all refracting surfaces are spherical. (05 Mar 2000) |
| spherocylindrical lens | A combined spherical and cylindrical lens, one surface being spherical, the other cylindrical. Synonym: spherocylinder. (05 Mar 2000) |
| negative lens | <physics> A lens with a negative focal length. The edge of a negative lens is thicker than the centre. The three negative lenses are, according to their figure: planoconcave, double concave or biconcave, and diverging concavoconvex or diverging meniscus. See: lens, simple. (05 Aug 1998) |
| nucleus of lens | The core or inner dense portion of the lens of the eye. Synonym: nucleus of lens. (05 Mar 2000) |
| decentered lens | A lens so mounted that the visual axis does not pass through the axis of the lens. (05 Mar 2000) |
| suspensory ligament of lens | A series of delicate meridional fibres arising from the inner surface of the orbiculus ciliaris that run in bundles between, and in a very thin layer over, the ciliary processes; at the inner border of the corona, the fibres diverge into two groups that are attached to the capsule on the anterior and posterior surfaces of the lens close to the equator; the spaces between these two layers of fibres are filled with aqueous humor. Synonym: zonula ciliaris, apparatus suspensorius lentis, suspensory ligament of lens, Zinn's zonule. (05 Mar 2000) |
| dislocation of lens | Congenital displacement of the lens resulting from defective zonule formation. (12 Dec 1998) |
| double concave lens | A lens that is concave on two opposing surfaces. Synonym: concavoconcave lens, double concave lens. (05 Mar 2000) |
| double convex lens | A lens with both surfaces convex. Synonym: convexoconvex lens, double convex lens. (05 Mar 2000) |
| immersion lens | An objective (for a microscope) constructed in such a manner that the lower lens may be moved downward into direct contact with a fluid which is placed on the object being examined; by using a fluid with a refractive index closely similar to that of glass, the loss of light is minimised. (05 Mar 2000) |
| immersion of a lens | <physics> With nearly all high-power lenses, it is intended that the spaces between the condenser and the slide, and the specimen and the front lens of the objective be filled with an immersion liquid. Owing to the limitations imposed by the critical-angle phenomenon, numerical apertures are impossible exceeding 1.0 without immersion. In addition, immersion makes possible the use of the naturally aplanatic points of the front lens element of the objective. (05 Aug 1998) |
| ocular lens | <physics> The lens nearest the eye in any ocular. (05 Aug 1998) |
| omnifocal lens | A lens for near and distant vision in which the reading portion is a continuously variable curve. (05 Mar 2000) |