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Approximately at the same time when the study began with space telescopes, the first attempts to reveal the secrets via microcosm lenses were made.

It is known that small objects, even if they are well lit, sending eye is too weak beam of light rays, intense enough to permit it produces on the retina, it has given us a clear image. The easiest way to increase the image of a small object - is watching it with a magnifying glass. Collecting called magnifier lens with short focal length (usually less than 10 cm) inserted into the handle.

Observation takes place through magnifier follows. AB Subject placed on the glass at a distance of the OC, the smaller the focal length Of, then the eye, located at the intersection point of the F-ray, will seem as if the rays come from the point of intersection of extended A1B1 rays, so that a sham, a direct enlarged image A1B1 AB object. To picture it was quite clear, it is necessary that the distance equal to the distance C1F was the best view of the observer. Magnifier increase will be considered relevant to the A1B1 AB or OC1 to the OC.

A more perfect tool for observing microscopic objects is a simple microscope. When were these devices, it is not known exactly. At the beginning of the XVII century, a few of these microscopes manufactured spectacled wizard Zacharias Janssen of Middelburg. The work of A. Kircher, published in 1646, contains a description of a simple microscope, which he called "flea glass." It consisted of a magnifying glass set into a copper base, which strengthened the stage, which served to place the object in question; At the bottom is flat or concave mirror reflecting the sun's rays on the subject and so light it from below. Lupu was moved by a screw to the stage, until the image becomes distinct and clear.

The first outstanding discoveries were made just a simple microscope. In the middle of XVII century the brilliant successes achieved Dutch scientist Antonie van Leeuwenhoek. For many years in the manufacture of improved Leeuwenhoek tiny (sometimes less than 1 mm in diameter) biconvex linzochek that it is made from a small glass ball, in turn, receives a result of melting of the glass rod in the flame. Then, the glass ball was subjected to grinding at a primitive grinding machine. Throughout his life, Leeuwenhoek produced no less than 400 of these microscopes. One of them is stored in the University Museum in Utrecht, gives more than 300-fold increase in that of the XVII century was a huge success.

Without a definite plan Leeuwenhoek explored everything that came to hand, and, like Galileo in space, one great discovery made by one. First used a microscope in zoological studies, he was a true pioneer of the microcosm. Thus, Leeuwenhoek first observed the movement of blood in the blood vessels and opened the red blood cells; he discovered that the eyes of insects arranged completely as a person, and has a faceted structure; he opened the transverse striation of muscles, tube dental material of the lens fibers, flakes of skin, and more. Even more important was the fact that Leeuwenhoek discovered a huge world of micro-organisms, the existence of which had not even suspected. He described the budding Hydra and many forms of ciliates. Finally, he found sperm in the seminal fluid of humans and animals and has shown that the development of large organisms, too, begins with microscopic dimensions.

At the beginning of the XVII century were sophisticated microscopes, made up of two lenses. The inventor of the compound microscope is not exactly known, but many facts speak for the fact that it was the Dutchman Cornelius Drebel, who lived in London and who was in the service of the English King James I. In the compound microscope had two windows: one - the lens - addressed to the subject, another - an eyepiece - facing the eye of the beholder. The first microscope objective served lenticular glass, let a real, magnified, but the opposite image. This image and viewed using an eyepiece, who played the role of a magnifying glass in this way, but it served as a magnifying glass to increase not the object itself and its image.

Subject AB, located a little further from the lens of its main focus the F, giving the other side a valid inverse and magnified image ab lying behind double the focal length. Glass M and N are interconnected in such a distance that the image falls between the eyepiece ab N and its main focus F1. It follows that the eyes placed on the E, see the image through the eyepiece, which acts like a magnifying glass image and replaces other ab - a1b1, imaginary and even increased. This second image directly to the first, but the reverse in relation to the subject.

Also this scheme are possible, and other microscope. By the way, the creator of the telescope Galileo in 1610 found that in the extended state of much of his telescope allows greatly increase small objects. It can be considered the inventor of the microscope, consisting of positive and negative lenses. In 1663 Drebelya microscope was perfected by the English physicist Robert Hooke, who made him the third lens, called the team. This type of microscope has gained a lot of popularity and most microscopes the end of XVII - the first half of the XVIII century, built by his scheme.

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