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HISTORY OF TECHNOLOGY, TECHNOLOGY, OBJECTS AROUND US
Telescope. History of invention and production
Directory / The history of technology, technology, objects around us A telescope is an instrument that helps in observing distant objects by collecting electromagnetic radiation (such as visible light).
Like glasses, the spotting scope was created by a person far from science. Descartes, in his Dioptric, speaks of this important invention as follows: “To the shame of the history of our sciences, such a remarkable invention was first made purely by experience and, moreover, by chance. About thirty years ago, Jacob Mecius, “a man who never studied the sciences,” who liked to arrange mirrors and burning glasses, having for this purpose various shapes of lenses, he decided to look through a combination of convex and concave glass, and then so successfully installed them at the two ends of the pipe that he quite unexpectedly received the first spotting scope. They say that he was prompted by children playing with glasses. Thus, the first spotting scope appeared in the Netherlands at the beginning of the 1608th century. Moreover, it was invented, in addition to Mecius, independently by several people at once. All of them were not optical scientists, but ordinary artisans. One of them, John Leppershey, a spectacle craftsman from Middelburg, presented the pipe he had created to the States General in 1610. Hearing about this novelty, the famous Italian scientist Galileo Galilei wrote in XNUMX: “About ten months ago, a rumor reached our ears that a certain Belgian built a perspective (as Galileo called the telescope), with the help of which visible objects, far from the eyes, become clearly distinguishable, as if they were close." Galileo did not know the principle of operation of the telescope, but he was well aware of the laws of optics and soon guessed about its device and designed the telescope himself. “First, I made a lead tube,” he wrote, “at the ends of which I placed two spectacle glasses, both flat on one side, on the other hand, one was convex-spherical, the other concave. By placing the eye at the concave glass, I saw objects enough large and close. Indeed, they seemed three times closer and ten times larger than when viewed by the natural eye. After that, I developed a more accurate tube, which represented objects magnified by more than sixty times. After this, sparing no effort and no means, I achieved that I built myself an organ so excellent that things seemed through it, when viewed, a thousand times larger and more than thirty times approximate than when viewed with the help of natural abilities. Galileo was the first to realize that the quality of lenses for spectacles and lenses for spotting scopes must be completely different. Of the ten glasses, only one was suitable for use in a spotting scope. He has perfected lens technology to a degree that has never been achieved before. This allowed him to make a telescope with a magnification of thirty times, while the telescopes of spectacle craftsmen were magnified only three times.
The Galilean telescope consisted of two glasses, of which the one facing the object (objective) was convex, that is, collecting light rays, and the one facing the eye (eyepiece) was concave, scattering glass. The rays coming from the object were refracted in the lens, but before giving an image, they fell on the eyepiece, which scattered them. With such an arrangement of glasses, the rays did not make a real image, it was already formed by the eye itself, which here constituted, as it were, the optical part of the tube itself. The lens O gave in its focus a real image ba of the observed object (this image is the opposite, as could be seen by taking it on the screen). However, the concave eyepiece O1, installed between the image and the lens, scattered the rays coming from the lens, did not allow them to cross, and thus prevented the formation of a real image ba. The diverging lens formed a virtual image of the object at points A1 and B1, which was at the best vision distance. As a result, Galileo received an imaginary, enlarged, direct image of the object.
The magnification of the telescope is equal to the ratio of the focal lengths of the objective to the focal length of the eyepiece. It would seem that it is possible to obtain arbitrarily large magnifications. However, technical possibilities put a limit to a strong increase: it is very difficult to grind glasses of large diameter. In addition, for too long focal lengths, an excessively long tube was required, which was impossible to work with. A study of Galileo's telescopes, which are kept in the Museum of the History of Science in Florence, shows that his first telescope gave a magnification of 14 times, the second - 19 times, and the third - 5 times. Although Galileo cannot be considered the inventor of the telescope, he was undoubtedly the first to create it on a scientific basis, using the knowledge that was known to optics by the beginning of the 30th century, and turning it into a powerful tool for scientific research. He was the first person to look at the night sky through a telescope. So he saw something that no one had seen before him. First of all, Galileo tried to consider the moon. On its surface were mountains and valleys. The peaks of mountains and cirques shone silver in the rays of the sun, and long shadows blackened in the valleys. Measuring the length of the shadows allowed Galileo to calculate the height of the lunar mountains. In the night sky, he discovered many new stars. For example, in the constellation Pleiades there were more than 80 stars, while before there were only seven. In the constellation of Orion - 8 instead of XNUMX. The Milky Way, which was previously considered as luminous pairs, crumbled in a telescope into a huge number of individual stars. To the great surprise of Galileo, the stars in the telescope seemed smaller in size than when observed with the naked eye, since they lost their halos. The planets, on the other hand, were represented as tiny discs, like the Moon. Pointing the pipe at Jupiter, Galileo noticed four small luminaries moving in space along with the planet and changing their positions relative to it. After two months of observations, Galileo guessed that these were the satellites of Jupiter, and suggested that Jupiter was many times larger than the Earth in size. Considering Venus, Galileo discovered that it has phases similar to those of the moon, and therefore must revolve around the Sun. Finally, observing the Sun through the violet glass, he found spots on its surface, and from their movement he established that the Sun rotates around its axis. All these amazing discoveries were made by Galileo in a relatively short period of time thanks to the telescope. They made a stunning impression on contemporaries. It seemed that the veil of secrecy had fallen from the universe, and it was ready to reveal its innermost depths to man. How great was the interest in astronomy at that time, can be seen from the fact that only in Italy, Galileo immediately received an order for a hundred instruments of his system. One of the first to appreciate Galileo's discoveries was another outstanding astronomer of that time, Johannes Kepler. In 1610, Kepler came up with a fundamentally new design of the spotting scope, which consisted of two biconvex lenses. The following year, he published the major work Dioptric, which examined in detail the theory of telescopes and optical instruments in general. Kepler himself could not assemble a telescope - for this he had neither the means nor qualified assistants. However, in 1613, according to Kepler's scheme, another astronomer, Scheiner, built his telescope.
Many scientists began to build telescopes themselves, more powerful than those of Galileo. Some managed to achieve an increase of a hundred times, while the length of the tube reached 30, 40 or more meters. The record belongs, apparently, to the astronomer Oz, who in 1664 managed to build a telescope with a magnification of 600 times. The length of the tube was 98 meters. It is easy to guess the difficulties that Oz had to endure in observing with such a clumsy device. In 1672, Isaac Newton managed to partially resolve this difficulty, he proposed a new design of the telescope (called a reflector), in which the lens was a concave metal mirror.
From all that has been said, it is clear that the creation of the telescope marked a genuine revolution in science in general and in optics in particular. Precise optics entered science as a new means of understanding the world. Author: Ryzhov K.V.
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