First magnifiers. Optical devices. History of creation

The human eye is designed in such a way that it is not able to clearly see an object and its details if its dimensions are less than 0.1 mm. But in nature there are various microorganisms, cells of both plant and animal tissues, and many other objects, the dimensions of which are much smaller. To see, observe and study such objects, a person uses a special optical device called microscope, which allows many hundreds of times to increase the image of objects that are not visible to the human eye. The very name of the device, consisting of two Greek words: small and look, speaks of its purpose. So, an optical microscope is able to magnify the image of an object by 2000 times. If the object being studied, such as a virus, is too small, and to increase it optical microscope not enough modern science uses an electron microscope, which allows you to magnify the observed object by 20,000-40,000 times.

The invention of the microscope is associated primarily with the development of optics. The magnifying power of curved surfaces was known as early as 300 BC. e. Euclid and Ptolemy (127-151), however, these optical properties did not find application at that time. Only in 1285 the Italian Salvinio deli Arleati invented the first glasses. There is evidence that the first microscope-type device was created in the Netherlands by Z. Jansen around 1590. Taking two convex lenses, he mounted them inside one tube, focusing on the object under study was achieved due to the retractable tube. The device gave a tenfold increase in the subject, which was a real achievement in the field of microscopy. Jansen made several such microscopes, significantly improving each subsequent device.

In 1646, A. Kircher's work was published, in which he described the invention of the century - the simplest microscope, called "flea glass". The magnifying glass was inserted into a copper base on which the object table was attached. The object under study was placed on a table, under which there was a concave or flat mirror that reflected the sun's rays onto the object and illuminated it from below. The magnifying glass was moved with a screw until the image of the object became distinct.

Compound microscopes made from two lenses appeared in the early 17th century. Many facts indicate that the inventor of the compound microscope was the Dutchman K. Drebel, who in the service of King James I of England. Drebel's microscope had two glasses, one (objective) was turned to the object under study, the other (eyepiece) was turned to the observer's eye. In 1633, the English physicist R. Hooke improved the Drebel microscope, supplementing it with a third lens, called the collective. Such a microscope gained great popularity; most microscopes of the late 17th and early 18th centuries were made according to its scheme. Examining thin sections of animal and plant tissues under a microscope, Hooke discovered the cellular structure of organisms.

And in 1673-1677, the Dutch naturalist A. Leeuwenhoek, using a microscope, discovered a previously unknown huge world microorganisms. Over the years, Leeuwenhoek made about 400 simple microscopes, which were small biconvex lenses, some of them less than 1 mm in diameter, obtained from a glass ball. The ball itself was polished on a simple grinding machine. One of these microscopes, giving a 300-fold magnification, is stored in Utrecht in the university museum. Exploring everything that caught his eye, Leeuwenhoek made great discoveries one after another. By the way, the creator of the telescope, Galileo, while improving the spotting scope he created, discovered in 1610 that, when extended, it significantly enlarges small objects. By changing the distance between the eyepiece and the lens, Galileo used the tube as a kind of microscope. Today you can't imagine scientific activity human without using a microscope. The microscope has found the widest application in biological, medical, geological laboratories and laboratories of materials science.

Already the ancient Romans drew attention to the "increasing power" of a vessel filled with water. They knew that through it in the sun you can get burned, light a fire, although the water in it does not boil.

About 400 years ago, skilled craftsmen in Italy and Holland learned how to make glasses. They were invented by an unknown glass master. Italian masters during this era they were famous for the art of grinding glass. Following glasses, magnifiers were invented for examining small objects. It was very interesting and captivating: to suddenly see in all details some grain of millet or a fly leg!

And the invention of the telescope goes into the realm of fairy tales. According to one Mohammedan legend, there was a huge mirror on the Lighthouse of Alexandria, with the help of which it was possible to see the ships sailing from Greece. However, due to the curvature of the Earth, the ships were visible from this lighthouse already quite far from Greece. According to this legend, it can be assumed that a combination of a large concave mirror with a lens was used there.

Optics enthusiasts, diligently studying the images obtained with the help of mirrors and lenses, of course, could not help but stumble upon the idea of ​​​​combining several mirrors and lenses in order to obtain images. From such combinations, a pipe and a microscope were gradually obtained. The authorship of these inventions does not belong to one specific person, but we can trace the history of their appearance.

The first description of an optical instrument was found in the writings of a Franciscan monk, an Englishman, Roger Bacon. But from them we can only conclude that Bacon knew the magnifying effect of convex lenses, found that concave mirrors focus parallel beams to a point lying between the center and the top of the mirror, represented the possibility of combining a lens and a mirror, put forward the idea of ​​​​creating a telescope and was the first to give it description in 1268

Realizing your dream to see the elusive eye, italian artist, scientist and inventor Leonardo da Vinci in 1509 gave a description and drawing of a two-lens spotting scope, developed machines for grinding lenses, and was the first to graphically construct the path of rays in lenses. Its optical improvements were not realized at that time and remained unknown.

The Italian physician Fracastoro from Verona, in his work, which appeared in 1538, claims that one can see objects much closer and in an enlarged form by placing two lenses one above the other. If we understand "above" literally, this means that he expressed the idea of ​​\u200b\u200bcreating a microscope.

writes even more precisely Italian inventor Giambattista della Porta in 1558 in his “Natural Magic”: “Through concave glass, distant objects are clearly visible, with the help of convex, close ones. If both types of these glasses are correctly combined, then both close and distant objects appear larger and clearer. The spotting scope that Porta describes was supposed to magnify very little. Otherwise, he would also have described some of the discoveries in the sky that could be made with the help of his pipe. But his book, which received great popularity, contributed to the fact that many amateurs became interested in this issue.

As a result, in 1608 in Holland, applications for a patent for the invention of a spotting scope were filed almost simultaneously by several researchers - Lippershey, J. Metzius, Hans and Zakharia Jansen. However this invention was of military importance and was classified. Rumor about the invention of a pipe that allows you to see clearly individual items, prompted G. Galileo to think about the design of such a device. He, independently of Dutch scientists, created his telescope in 1609 and used it to observe on land and at sea, and most importantly, by pointing it to the sky, he achieved remarkable results: he discovered the satellites of Jupiter, spots on the Sun, individual stars Milky Way etc. As a result, for a long time the honor of the invention of the telescope was attributed to G. Galileo. Today, the spotting scope, sometimes called the Dutch or Galilean, is used mainly in binoculars with low magnification.

Galileo was the first scientist to take seriously the idea of ​​creating optical instruments. Having organized workshops for the production of spotting scopes in 1624, G. Galileo created a microscope. The tubes of his devices were made of paper, it is not surprising that such devices quickly fell into disrepair, the lenses fell out and collapsed. However, these devices were very popular, because in a short time G. Galileo became a supplier of optical devices to famous European courts.

And modern spotting scopes for astronomical and terrestrial observations are usually built according to I. Kepler's scheme. In 1611, I. Kepler proposed a spotting scope, which consisted of two convex lenses. One of them gives a real image of the object. This image is magnified by the second lens. The resulting image is the opposite. Therefore, such a telescope is inconvenient for viewing terrestrial objects.

Another form of pipe was proposed in 1645 by the Capuchin monk Shirl from Bohemia. This pipe had an advantage over I. Kepler's pipe, because. thanks to the addition of two internal lenses that flip the image, it has become convenient for ground-based observations. Shirl was the first to call the lens facing the object - the objective, and facing the eye - the eyepiece.

Anthony Van Leeuwenhoek, a Dutch naturalist, learned how to make lenses with 150-300-fold magnification. He used them in a microscope. In 1673, Leeuwenhoek was the first to observe and draw micro-organisms in a drop of water, capillary vessels in the tail of a tadpole, red blood cells, and hundreds of other amazing things that no one suspected.

Modern microscopes give an increase of one and a half to two thousand times, and electronic ones - even a million times! Of course, we cannot make a real microscope with you. But we can build a magnifying glass a little like the one used by the ancients.

A very simple magnifying device can be made from thin thick paper, in which you need to carefully pierce a hole with a pin and place a drop of water on it. This device acts like a magnifying glass. Bring the hole to the very eye and look through it at least at book page, but only from a distance of about 2 cm. Nothing so close can be seen with the naked eye. And through the hole, the letters will seem very large, as if not in a book, but on a poster.

In this way, you can consider, for example, a small bug, a fly's foot, and you never know what else. There is only one condition: the observed object must be very brightly lit.

Check it out and explain the phenomenon.

The presentation gives an idea of ​​the species magnifying devices, the history of their discovery, the rules of work. This presentation can be used in biology lessons in grade 6, as well as in nature studies in grade 5.

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Biology teacher MBOU secondary school No. 73 named after. A. F. Chernonoga Soshnikova Tatyana Anatolyevna Magnifying devices

The purpose of the lesson: to study the material about the history of the discovery and the device of magnifying devices; microscope rules.

The first microscopes were optical, and their first inventor is not so easy to single out and name. The earliest information about the microscope dates back to 1590 and the city of Middelburg, in Holland, and is associated with the names of Joan Lippershey (who also developed the first simple optical telescope) and Zacharias Jansen, who were engaged in the manufacture of glasses

A little later, in 1624, Galileo Galilei presents his compound microscope, which he originally called "occhiolino" (occhiolino, ital. - small eye). A year later, his Academy friend Giovanni Faber coined the term microscope for the new invention.

Historical background Robert Hooke (16th century)

Historical background Improved the microscope and discovered unicellular organisms. Anthony van Leeuwenhoek (17th century)

18th century microscopes

Hand and stand magnifier Light microscope Electron microscope magnifying devices

What is a loupe and how much magnification does it give?

hand magnifier magnifying glass(lens) handle A hand held magnifier magnifies from 2x to 20x. frame

tripod magnifier tripod mirror object table eyepiece Tripod magnifier magnifies objects from 10 to 25 times.

How to determine the magnification of a microscope? Look at the number on the eyepiece.

How to determine the magnification of a microscope? Look at the number on the lens.

To find out how much the image is enlarged when using a microscope, you need to multiply the number indicated on the eyepiece by the number indicated on the object used.

When working with a microscope, it is recommended to observe the following rules: Place the microscope with a tripod towards you, at a distance of 5-10 cm from the edge of the table. Direct the light with a mirror into the opening of the stage. Prepare the preparation, place it on the object table and fix the glass slide there with two clamps. Using the screw, smoothly lower the tube so that the lower edge of the lens is at a distance of 1-2 mm from the preparation. Looking through the eyepiece, slowly raise the tube until a clear image of the object appears. Put the microscope back in its case after use.