convex lens

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Related to convex lens: concave lens


1. a piece of glass or other transparent material so shaped as to converge or scatter light rays. See also glasses.
2. the transparent, biconvex body separating the posterior chamber and the vitreous body of the eye; it refracts (bends) light rays so that they are focused on the retina. Called also crystalline lens. In order for the eye to see objects close at hand, light rays from the objects must be bent more sharply to bring them to focus on the retina; light rays from distant objects require much less refraction. It is the function of the lens to do accommodation, making of adjustments for viewing both near objects and more distant ones. To accomplish this it must be highly elastic so that its shape can be changed and made more or less convex. The more convex the lens, the greater the refraction. Small ciliary muscles create tension on the lens, making it less convex; as the tension is relaxed the lens becomes more spherical in shape and hence more convex.

With increasing age the lenses lose their elasticity; thus their ability to focus light rays in the retina becomes impaired. This condition is called presbyopia. In farsightedness (hyperopia) the image is focused behind the retina because the refractive power of the lens is too weak or the eyeball axis is too short. Nearsightedness (myopia) occurs when the refractive power of the lens is too strong or the eyeball is too long, so that the image is focused in front of the retina.
The biconvex lens of the eye. From Frazier et al., 1996.
achromatic lens one corrected for chromatic (color) aberration.
apochromatic lens one corrected for chromatic (color) and spheric aberration.
biconcave lens one concave on both faces.
biconvex lens one convex on both faces.
bifocal lens one having two segments with different refracting power, the upper for far vision and the lower for near vision. See also bifocal glasses.
concave lens one curved like a section of the interior of a hollow sphere; it disperses light rays. Called also diverging lens.
contact l's corrective lenses that fit directly over the cornea of the eye; see also contact lenses.
converging lens (convex lens) one curved like the exterior of a hollow sphere; it brings light to a focus.
convexoconcave lens one that has one convex and one concave face.
crystalline lens lens (def. 2).
cylindrical lens one with at least one nonspherical surface, used to correct astigmatism.
diverging lens concave lens.
honeybee lens a magnifying eyeglass lens designed to resemble the multifaceted eye of the honeybee. It consists of three or six small telescopes mounted in the upper portion, directed toward the center and right and left visual fields. Prisms are included to provide a continuous, unbroken magnified field of view.
omnifocal lens one whose power increases continuously and regularly in a downward direction, avoiding the discontinuity in field and power inherent in bifocal and trifocal lenses.
orthoscopic lens one that gives a flat and undistorted field of vision, especially at the periphery.
planoconcave lens a lens with one plane and one concave side.
planoconvex lens a lens with one plane and one convex side.
Stokes's l's an apparatus used in the diagnosis of astigmatism.
trial l's ones used in testing the vision.
trifocal lens one having three segments of different refracting powers, the upper for distant, the middle for intermediate, and the lower for near vision.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

con·vex lens

a converging lens.
Synonym(s): plus lens
Farlex Partner Medical Dictionary © Farlex 2012

con·vex lens

(kon-veks' lenz)
A converging lens.
Medical Dictionary for the Health Professions and Nursing © Farlex 2012
References in periodicals archive ?
Type III: The cross-section surface of the butt is in the shape of a convex lens. There are faces on the sides, the sides arc parallel and the polls are flat and linear (No.
Consider the geometry which contains a plano convex lens placed in chiral medium as shown in Figure 1.
Now, according to a report in New Scientist, Vera Smolyaninova of Towson University in Baltimore, Maryland, and colleagues have used a convex lens to create the tapered waveguide and trap a rainbow of light.
When light or an object is placed in front of a convex lens at any distance, the exiting light or picture will converge into a point on the other side of the lens.
So why did Thomas Digges not come up with a viable example of a simple telescope similar to mine, using his combination of a convex lens objective and a concave mirror eyepiece?
The curve of a convex lens spreads out an image so that it takes up a larger portion of your retina and looks bigger.
The first thing to check is that the focus lies the proper distance from the corrector: 11.45 inches from the middle of the corrector's convex lens element.
A camera obscura creates an image when light entering a darkened box through a tiny hole is focused upon the opposite interior surface by means of a convex lens.
He placed a convex lens at each end of a tube and found that magnification was indeed improved.
The hologram in the lower left-hand comer appears to be full parallax and shows the DNP logo beneath a convex lens, it has black backing so nothing can be seen through it and has its own space on the card.
As an experiment I sent an old 1-inch convex lens out to be aluminized.