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The principle of jewellery identification magnifying glass
Release time:2017-12-13 browse:1526second

A magnifying glass, used for simple visual observation optical device details of objects, is the ratio of the focal length lens eye distance much smaller. The size of an object in the retina of a human eye is proportional to the angle (angle of view) of the eye. The more the view is, the larger the image is, the more it can distinguish the details of the object. Moving near the object can increase the angle of view, but it is limited by the ability to focus on the eye. Use a magnifying glass to close to the eyes, and put an object within its focus, a positive image. The function of the magnifying glass is to enlarge the angle of view.

First explains several concepts: convex lens has a convergent effect on light, parallel to the main optical axis of light through the lens will be brought to a point. This is the focus of the convex lens, focus and center (the center of the convex lens focal length is the distance). When the object within the lens focal length, showed a positive amplification of the virtual image. When an object between the convex lens of 1 times to 2 times the focal length, was an inverted image magnification. When the material fixed on the convex lens focal length outside 2 times, is a narrow inverted image. We use a magnifying glass, is placing the object in focus, then through the convex lens is to see the magnified virtual image, and magnifying the farther away from the object, the virtual image is larger (1 times less than the focal length).

Basically, there is no clear information about when the magnifying glass was invented, but it was certainly not later invented later in the late thirteenth Century. More than a thousand years ago, transparent crystals or stones had been grind into a "lens", which magnified the image. It was rumored that the masterpiece was invented by some people at the end of the thirteenth Century. In 1260, Marco Polo once described Chinese people read when wearing glasses increase the font, large oval, crystal stone, quartz, topaz, Amethyst grinding lenses, and insert as picture frame in tortoise shell glasses, a foot in a copper card at the temples, two string tied in the ears, three the mirror is fixed on the cap on foot. The magnifying glass is not expensive, the status symbol, once recorded that a gentry used a horse for a pair of glasses. In the world, the famous international brands are mainly concentrated in Europe, and the top three famous brands in the world are in Europe. There are no famous magnifying glass brands in the United States and Japan.