How familiar are you with magnifiers? Grade 5 of high school is the time when we first get to know them. In the lessons, children are told the most basic things about their device and creators. Would you like to deepen your knowledge of them? Or maybe you are preparing a lesson on the topic "Magnifying devices" (Grade 5)? In any case, we have something to tell you.
Ancient lenses
The history of the discovery of magnifying devices begins in the distant past. A large flat-convex lens has come down to us - one of the oldest. Its diameter is 55 mm, and the focal length is about 150 mm. It was made of rock crystal for 2.5 thousand years BC. e. It was discovered in 1890 by G. Schliemann during excavations of Troy. Around 600-400. BC e. began to make glass lenses. They were discovered in Sargon (this is Mesopotamia). In Sweden in 1877 a double lens with a diameter of 5 cm was found, convex on both sides. It refers to the year 500 A.D. e. You can continue the list of ancient lenses that researchers were able to find for a long time. The history of the discovery of magnifying devices has many facts. Despite this, how they were used in those days can only be speculated.
Contribution of Roger Bacon
Modern scientists have familiarized themselves with the thorough description of lenses made by Roger Bacon, a monk of the Franciscan Order (years of life - 1214-1294). He was a graduate of Oxford University, and also became famous as a prominent thinker and scientist. Lenses, according to his work, were used to enlarge the image. From the translation of the fragment of the work it follows that Bacon was able to correctly describe the action of the lenses that served as the inverse telephoto lens (we are talking about the description of a one-component visual tube).
Merit of Galileo Galilei
The history of the discovery of magnifying devices is unthinkable without the name of this person. About 300 years after the death of Bacon, Galileo Galilei, a famous scientist from Italy, created a similar pipe. She was not three, but two-component. Practically the “peer” of such a telescope is a microscope. It is generally accepted that he owes his appearance to Galileo. Galileo parted the telescope and noticed that small objects in this state can be magnified well. D. Viviani confirms that it was Galileo who invented the microscope. Viviani, by the way, wrote a biography of this Italian scientist.
An important event for science was the history of the discovery of magnifying devices in 1625. It was then that Faber, a member of the Roman Academy, first used the term "microscope" in relation to the invention made by Galileo.
What created Drebel and Alkmaar, the development of Tore and Hooke
The history of the discovery of the microscope continues with the work of K. Drebel and Alkmaar. These Dutch scientists designed a device that consisted of two convex lenses. Thanks to this, the image of the object, which was examined under it, was presented upside down. This complex microscope, which had a biconcave or plane-convex eyepiece, as well as a biconvex lens, is considered the predecessor of complex microscopes of a later time (one of them is shown in the photo below).
The Italian Tore approximately in 1660 made spherical magnifying glasses from the frozen drops of glass. The history of the discovery of the microscope is inconceivable without this name, since the magnifier created by the Italian allowed magnifying objects 1,500 times.
Is there another name telling you something - Robert Hooke? This English scientist made a great contribution to the discovery of magnifying devices. Robert Hook perfected them so much that it became one of the significant events in the history of optics. The Hooke microscope diagram is shown in the photo below.
Thanks to this invention, in 1665, Robert was able to see cells for the first time on a section of a cork. So, an important technical tool has received such a science as biology. Magnifying devices continued to improve Levenguk. We will tell about him too.
Levenguk and his achievements
A significant contribution to the history of the development of magnifying devices was made by A.V. Levenguk, a Dutchman who lived in a city such as Delft. The years of his life - 1632-1723. He independently constructed and used simple microscopes in research (one of the models of such devices is presented below), capable of magnifying up to three hundred times.
It was Levenguk who first compiled a description of microscopic organisms (including unicellular bacteria), based on his observations. In 1698, Peter I, the Russian Tsar, paid a visit to this famous explorer. Peter was at that time in Holland and, as you know, was interested in everything new. For his Kunstkamera, which he opened in St. Petersburg, he purchased several complex and simple microscopes. And much later, after the opening of the Academy of Sciences, they were transferred to the disposal of this organization.
The works of Russian scientists from the Academy of Sciences
The lesson “Magnifying devices” should also include a story about the achievements in optics of representatives of our country. Promising Russian scientists, whose work was supervised by MV Lomonosov, began to use microscopes purchased by Peter the Great in biological research. And subsequently they actively participated in their improvement.
The discovery of magnifying devices continued in 1747. It was then that L. Euler, a member of the St. Petersburg Academy of Sciences (years of life - 1707-1783), proposed using an achromatic lens for a microscope. The fundamental work of this scientist in the field of geometric optics - "Diopter". It consists of three volumes, which were published in 1769-1771. A new microscope, already achromatic, was released in 1802 after the work of Elinus (also a member of the Academy of Sciences of St. Petersburg) was published.
Such a microscope at that time was considered perfect to such an extent that scientists did not even allow the idea that it could be improved. The discovery of this made a lot of noise at that time. The device of magnifying devices of Elinus was as follows. They were equipped with six lenses, it was possible to change the magnification smoothly, the distance from the subject to the image changed. It was in our country that the idea of an achromatic microscope with a variable magnification, important for science, was born and came to life. However, this idea did not take root in further developments. Changing the magnification of the device by adjusting the length of the tube, however, was an important idea that made a significant contribution to the history of the development of optical devices. Today one of the microscopes created by Elinus can be seen in the Polytechnic Museum of Moscow, which belongs to the Institute of History, Natural Sciences and Technology. The photo below shows magnifying instruments dating back to the 18th century.
Further refinement of microscopes
I. G. Tiedemann, a German optician from the city of Stuttgart, at the beginning of the 19th century set about creating two achromatic microscopes. The University of Dorpat (today it is called Tartu) allocated him funds to carry out work. In 1808, these devices were released.
In 1807, the year before the creation of achromatic microscopes, Van Dale, a Dutch optician, published his work. It presented a description of the design of the achromatic microscope created by him. Western European historians believe that the microscope created by this scientist was the first such device of satisfactory quality. However, in all respects it was inferior to that designed by Elinus. By the way, I. Fraunhofer achromatic microscopes, released in 1811, were distinguished by an even more imperfect design when compared with Elinus microscopes.
Russian microscopes in the 19th century
In the first half of the 19th century, magnifying devices were already available in many places on earth. In Russia, their production began in the 18th century, but subsided by the beginning of the 19th century. It is known that around 1820, rather high-quality microscopes were produced by the optics workshop located at Kazan University. However, in Russia there was still no rapid development of this industry, since the government of that time believed that the purchase of magnifying devices abroad was the best option.
Contribution to the optics of Jambattista and Amici
Amici Jambattista (years of life - 1786-1863) is a famous Italian scientist-optician, astronomer and botanist. He devoted many years of his life to the development of microscopy. In 1827, Amichi himself designed and made an achromatic lens, which had an aperture of 0.60 and a good correction of aberrations. The same scientist in 1844 began experiments on the use of water and oil immersions. Thanks to them, the production of lenses with a numerical aperture of 1.30 and water immersion was launched.
Microscopes Abbe
Devices with oil immersion having an aperture of 1.50 (which are still used today) began to be produced thanks to the work of Ernst Abbe, a German optician. He invented the law of sines, with the help of which the coma observed in small linear fields was eliminated. E. Abbe continued to develop the theory of image formation in a magnifying device. He clarified the issue of the resolution of these devices. Abbe was the leader in creating a whole series of high-quality achromatic micro lenses. Their numerical aperture reached 1.50. These devices were produced in Jena by C. Zeiss (in 1872). The same company, under the leadership of E. Abbe, made 8 apochromats. And in 1888, its employees developed an apochromat, which had an aperture of 1.60 and had monobromo-naphthalene immersion.
Recent major advances in optics
Russian scientists D. S. Rozhdestvensky and L. I. Mandelstam developed Ernst's theory in their writings. An important merit of Rozhdestvensky was that he introduced the concept of the relative incoherence of lighting. R. Richter, an employee of K. Zeiss, developed and obtained a patent for a special lighting device used in a microscope. However, to this day, the problem of the optimal ratio of the parameters of interchangeable lenses and the lighting system is relevant. Domestic microscopes today are in no way inferior in technical performance and optical parameters to instruments created by well-known companies abroad.
So, we briefly described the history of the emergence of modern microscopes. When developing the lesson "Magnifying devices" (Grade 5), you can use the information presented in the article.