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Historical Facts

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Historical Facts Lenses | Glasses | Contact Lenses | Telescopes | Microscopes Lenses As you can guess, a lens doesn’t always have to be glass. Thefirst lens was a container of water. It was discovered by the ancientRoman writer Seneca (4 B.C.-65 A.D.?). He found that images becamemagnified when seen through a glass ball filled with water. Roger Bacon (1214-1292?) invented the first convex lens in 1250. Concave lens were first used around 1450. Glasses Glasses were used in Italy around 1300. Old glasses were fastened withclips, rings, ribbons, weights, and other flexible things, or weresimply held by the hand. Temples weren’t invented yet! They had framesof tortoiseshell, ivory, metal (heavy metal), or wood. They were prettyheavy. Temples were finally invented in the 1740’s. Lorgnettes(pronounced lorn-YETS ) were also popular in the late 1700s. This word comes from the French word lorgner , meaning to leer at or stare. These were glasses held by a handle. ...
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Types of Lenses

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Types of Lenses Prisms | Convex Lenses | Concave Lenses Prisms How a prism bends light Obtained from www.howstuffworks.com Thesimplest kind of lens is actually a prism. A prism is a piece of glassshaped like a triangle and bends light towards its thickest part (thebottom of the “triangle”), which is called the base. The thinnest partof a lens is called the apex. Notall lenses are prisms, but any lens can be thought as two roundedprisms joined together. The same rules would apply, so all lenses bendlight towards their base. Convex Lenses The kinds of convex lenses* Convexlenses are known as many names, being also called positive lenses, pluslenses, converging lenses, and condensers. Convex lenses are fat in themiddle and skinny on the edges. There are three main types of convexlenses: plano-convex lenses, double-convex lenses, and concavo-convexlenses. Concavo-convex lenses have another name—positive meniscus. How a convex lens bends light Obtained from www.hows...
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Vision Correction

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Vision Correction Introduction | Myopia | Hyperopia | Presbyopia | Astigmatism | Strabismus | Cataracts Introduction How a normal eye focuses Obtained from Encarta Encyclopedia 2004 The eye normally focuses the image on the retina. This is accomplishedby a convex lens inside the eye that can become wider or narrower tocondense the light. Sometimes, however, something inside the eye is notfunctioning correctly. This makes the vision blurry or disoriented insome other fashion. I am going to explain these disorders and howlenses correct them. Below is how people with an eye disorder see the world. A stigmatism Obtained from www. allaboutvision. com C ataract Obtained from www.nei. nih.gov Hyperopia Obtained from www. allaboutvision. com M yopia Obtained from www. allaboutvision. com Strabismus Obtained from www. allaboutvision. com Glasses are lenses inside a frame. Contact lenses are pieces of plastic or glass that rest on the eye, separated from the ...
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