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HISTORY OF TECHNOLOGY, TECHNOLOGY, OBJECTS AROUND US
Microscope. History of invention and production
Directory / The history of technology, technology, objects around us A microscope is a device designed to obtain enlarged images, as well as to measure objects or structural details that are invisible or poorly visible to the naked eye.
Approximately at the same time when the exploration of space with the help of telescopes began, the first attempts were made to reveal the secrets of the microcosm with the help of lenses. It is known that small objects, even if they are well illuminated, send to the eye a beam of light rays that is too weak, not intense enough for the resolution it produces on the retina of the eye to give us a distinct image. The easiest way to magnify an image of a small object is to observe it with a magnifying glass. A magnifying glass is a converging lens with a small focal length (usually no more than 10 cm) inserted into the handle. Observation with a magnifying glass is as follows. The object AB is placed from the glass at a distance OC less than the focal length Of, then to the eye located at the point of intersection of the rays F, it will seem as if the rays come from the point of intersection A1B1 of the continued rays, so that an imaginary, direct magnified image A1B1 of the object AB is obtained. In order for this image to be perfectly distinct, it is necessary that the distance C1F be equal to the distance of the best view of the observer. The ratio of A1B1 to AB or OC1 to OC will be considered as magnification of the magnifying glass.
A more perfect tool for observing microscopic objects is a simple microscope. When these devices appeared, it is not known exactly. At the very beginning of the 1646th century, several such microscopes were made by the spectacle craftsman Zacharias Jansen from Middelburg. The work of A. Kircher, published in XNUMX, contains a description of the simplest microscope, which he called "flea glass". It consisted of a magnifying glass embedded in a copper base, on which an object table was fixed, which served to place the object in question; at the bottom there was a flat or concave mirror, reflecting the sun's rays onto an object and thus illuminating it from below. The magnifying glass was moved by means of a screw to the object table until the image became distinct and clear.
The first outstanding discoveries were made just with the help of a simple microscope. In the middle of the 1th century, the Dutch naturalist Anthony van Leeuwenhoek achieved brilliant success. Over the years, Leeuwenhoek perfected himself in the manufacture of tiny (sometimes less than 400 mm in diameter) biconvex lenses, which he made from a small glass ball, which in turn was obtained by melting a glass rod in a flame. Then this glass ball was ground on a primitive grinding machine. During his life, Leeuwenhoek made at least 300 such microscopes. One of them, kept in the University Museum in Utrecht, gives more than XNUMXx magnification, which was a huge success for the XNUMXth century.
Without a definite plan, Leeuwenhoek explored everything that came to hand, and, like Galileo in space, made one great discovery after another. For the first time using a microscope in zoological research, he was a true discoverer of the microworld. Thus, Leeuwenhoek was the first to observe the movement of blood in blood vessels and discovered red blood cells; he discovered that the eye of insects is completely different from that of humans, and has a faceted structure; he discovered the transverse striation of muscles, the tubules of the dental substance, the fibers of the lens, the scales of the skin, and much more. Even more important, Leeuwenhoek discovered a vast world of micro-organisms that had not even been known to exist before. He described the budding of hydras and many forms of ciliates. Finally, he discovered spermatozoa in the seminal fluid of humans and animals and showed that the development of large organisms also begins with microscopic sizes. At the beginning of the XNUMXth century, compound microscopes appeared, made up of two lenses. The inventor of such a compound microscope is not exactly known, but many facts indicate that he was the Dutchman Cornelius Drebel, who lived in London and was in the service of the English King James I. The compound microscope had two glasses: one - a lens - facing the subject, the other - the eyepiece - facing the eye of the observer. In the first microscopes, a biconvex glass served as an objective, which gave a real, enlarged, but inverse image. This image was examined with the help of an eyepiece, which thus played the role of a magnifying glass, but only this magnifying glass served to magnify not the object itself, but its image. Object AB, located a little further from the lens than its main focus F, gave on the other side a real, inverse and enlarged image ab, which lay beyond double the focal length. Glasses M and N are located at such a distance from each other that the image ab falls between the eyepiece N and its main focus F1. It follows that the eye placed on E sees the image through the eyepiece, which acts as a magnifying glass and replaces the image ab with another - a1b1, imaginary and even more magnified. This second image is direct in relation to the first, but reverse in relation to the subject.
In addition to this scheme of the microscope, others are possible. By the way, the creator of the telescope, Galileo, discovered in 1610 that in a highly extended state, his spotting scope allows you to greatly enlarge small objects. He can be considered the inventor of the microscope, consisting of positive and negative lenses. In 1663, the Drebel microscope was improved by the English physicist Robert Hooke, who introduced a third lens into it, called the collective.
This type of microscope gained great popularity, and most microscopes of the late XNUMXth and first half of the XNUMXth centuries were built according to this scheme. Author: Ryzhov K.V.
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