Lens & Its Applications

8/4/2019 Lens & Its Applications

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LENS & ITS APPLICATIONS

Done by:Yang Zhenyan (32)Yang Xinyi (31)Jordan Leong (11)Caven Teo (02)


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Introduction

A lens is just a curved piece of glass or plastic.Its job is to take the beams of light bouncingoff of an object and redirect them so theycome together to form a realimage-- animage that looks just like the scene in front ofthe lens.


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Types of Lens

Double-convex (Bi-convex)

Plano-Convex

Positive Meniscus

Negative Meniscus

Plano-Concave

Double-concave (Bi-concave


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Convex Lens

In a standard converging, or convex lens, oneor both sides of the glass curves out. Thismeans rays oflight passing through willbend toward the center of the lens onentry.

In a double convex lens, such as a

magnifying glass, the light will bend when itexits as well as when it enters.


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Concave Lens(contd)

A collimated beam of lighttravelling parallel to thelens axis and passing

through the lens will beconverged (orfocused) to aspot on the axis, at acertain distance behind thelens (known as thefocal

length). In this case, thelens is calledapositive or converging lens.


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Concave Lens

a collimated beam of lightpassing through the lens isdiverged (spread); the lens isthus calleda negative or diverging lens.The beam after passingthrough the lens appears tobe emanating from aparticular point on the axis infront of the lens; the distancefrom this point to the lens isalso known as the focallength, although it is negativewith respect to the focallength of a converging lens.


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Uses & applications of lens

A single convex lens mounted in a frame with ahandle or stand is a magnifying glass.

Lenses are used as prosthetics for the correctionof visual impairments suchas myopia, hyperopia, presbyopia, and astigmatism.

Sunglasses' lenses are designed to attenuate light;sunglass lenses that also correct visual impairmentscan be custom made.

Radio astronomy and radar systems oftenuse dielectric lenses, commonly called a lensantenna to refract electromagnetic radiation into acollector antenna.


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Uses & applications of lens

Other uses are in imaging systems suchas monoculars, binoculars, telescopes, microscopes, camerasand projectors. Some of these instruments produce a virtualimage when applied to the human eye; others produce a realimage which can be captured on photographic film or

an optical sensor, or can be viewed on a screen. Convex lenses produce an image of an object at infinity at

their focus; if the sun is imaged, much of the visible andinfrared light incident on the lens is concentrated into thesmall image.

Since ignition can be achieved even with a poorly made lens,lenses have been used as burning-glasses for at least 2400years. A modern application is the use of relatively large lensesto concentrate solar energy on relatively small photovoltaic

cells, harvesting more energy without the need to use larger,more expensive, cells.


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Lens & Its Applications