The invention of the first telescope is often credited to Hans Lipperschlei of Holland, 1570-1619, but he was almost certainly not the discoverer. Most likely, he just made the telescope popular and in demand. But at the same time, he did not forget to file a patent application in 1608 for a pair of lenses placed in a tube. He called the device a spyglass. However, his patent was rejected because his invention seemed too simple.
By the end of 1609, thanks to Lipperschleu, small telescopes had become common throughout France and Italy. In August 1609, Thomas Harriot refined and improved the invention, which allowed astronomers to view craters and mountains on the Moon.
The big break came when the Italian mathematician Galileo Galilei learned of a Dutchman's attempt to patent a lens tube. Inspired by the discovery, Galileo decided to make such a device for himself. In August 1609, it was Galileo who built the world's first full-fledged telescope. At first it was just a telescope - a combination of spectacle lenses, today it would be called a refractor. Before Galileo, most likely, few people knew how to use this tube for the benefit of astronomy. Thanks to the device, Galileo discovered craters on the moon, proved its sphericity, discovered four moons of Jupiter, the rings of Saturn.
The development of science made it possible to create more powerful telescopes, which made it possible to see a lot more. Astronomers began to use long focal length lenses. The telescopes themselves turned into huge, heavy tubes and, of course, were not convenient to use. Then tripods were invented for them.
By 1656, Christian Huyens made a telescope that magnifies objects observed 100 times, its size was more than 7 meters, and the aperture was about 150 mm. This telescope is already at the level of today's amateur telescopes. By the 1670s, a 45-meter telescope was built that magnified objects even more and gave a wider angle of view.
But even the usual wind could be an obstacle to obtaining a clear and high-quality image. The telescope began to grow in length. The discoverers, trying to squeeze the maximum out of this device, relied on the optical law they discovered: a decrease in the chromatic aberration of a lens occurs with an increase in its focal length. To remove chromatic interference, the researchers made telescopes of the most incredible length. These pipes, which were then called telescopes, reached 70 meters in length and caused a lot of inconvenience in working with them and setting them up. The disadvantages of refractors have led great minds to look for solutions to improve the telescope. The answer and a new method was found: the collection and focusing of the rays began to be done using a concave mirror. The refractor was reborn into a reflector, completely freed from chromatism.
This merit belongs entirely to Isaac Newton, it was he who managed to give new life to telescopes with the help of a mirror. Its first reflector was only four centimeters in diameter. And he made the first mirror for a telescope with a diameter of 30 mm from an alloy of copper, tin and arsenic in 1704. The image is clear. By the way, his first telescope is still carefully preserved in the Astronomical Museum in London.
But for a long time, opticians did not manage to make full-fledged mirrors for reflectors. The year of birth of a new type of telescope is considered to be 1720, when the British built the first functional reflector with a diameter of 15 centimeters. It was a breakthrough. In Europe, there is a demand for portable, almost compact telescopes two meters long. They began to forget about 40-meter pipes of refractors.
The XVIII century could well be considered the century of the reflector, if not for the discovery of English opticians: a magical combination of two lenses from crown and flint.
The two-mirror system in the telescope was proposed by the Frenchman Cassegrain. Cassegrain could not fully realize his idea due to the lack of technical feasibility of inventing the necessary mirrors, but today his drawings have been implemented. It is the Newton and Cassegrain telescopes that are considered the first "modern" telescopes invented at the end of the 19th century. By the way, the Hubble Space Telescope works just like the Cassegrain telescope. And Newton's fundamental principle with the use of a single concave mirror has been used at the Special Astrophysical Observatory in Russia since 1974. Refractory astronomy flourished in the 19th century, when the diameter of achromatic objectives gradually grew. If in 1824 the diameter was another 24 centimeters, then in 1866 its size doubled, in 1885 it began to be 76 centimeters (Pulkovo Observatory in Russia), and by 1897 the Yerksky refractor was invented. It can be estimated that over the course of 75 years, lens lenses have increased at a rate of one centimeter per year.
By the end of the 18th century, compact, handy telescopes had replaced bulky reflectors. Metal mirrors also turned out to be not very practical - expensive to manufacture, and also dull with time. By 1758, with the invention of two new types of glass: light - crown - and heavy - flint - it became possible to create two-lens lenses. The scientist J. Dollond made good use of this when he made a two-lens lens, later named Dollond.
After the invention of achromatic lenses, the victory of the refractor was absolute; all that remained was to improve the lens telescopes. Concave mirrors were forgotten. It was possible to revive them with the hands of amateur astronomers. So William Herschel, an English musician, discovered the planet Uranus in 1781. His discovery had no equal in astronomy since ancient times. Moreover, Uranus was discovered using a small homemade reflector. The success prompted Herschel to start making larger reflectors. Herschel in the workshop with his own hand fused mirrors from copper and tin. The main work of his life is a large telescope with a mirror 122 cm in diameter. Thanks to this telescope, discoveries were not long in coming: Herschel discovered the sixth and seventh satellites of the planet Saturn. Another, no less famous amateur astronomer, the English landowner Lord Ross, invented a reflector with a mirror 182 centimeters in diameter. Thanks to the telescope, he discovered a number of unknown spiral nebulae.
The Herschel and Ross telescopes had many disadvantages. Mirror metal lenses were too heavy, reflected only a fraction of the incident light, and dimmed. A new and perfect material for the mirrors was required. This material turned out to be glass. In 1856, the French physicist Leon Foucault tried to insert a mirror made of silvered glass into a reflector. And the experience was a success. Already in the 90s, an amateur astronomer from England built a reflector for photographic observations with a glass mirror 152 centimeters in diameter. Another breakthrough in telescopic construction was obvious.
This breakthrough was not without the participation of Russian scientists. I'M IN. Bruce became famous for developing special metal mirrors for telescopes. Lomonosov and Herschel, independently of each other, invented a completely new telescope design, in which the main mirror tilts without the secondary one, thereby reducing the loss of light.
The German optician Fraunhofer put the production on the conveyor and improved the quality of the lenses. And today in the Tartu Observatory there is a telescope with a working Fraunhofer lens. But the refractors of the German optician were also not without a flaw - chromatism.
It was only by the end of the 19th century that a new method of producing lenses was invented. Glass surfaces began to be treated with a silver film, which was applied to a glass mirror by exposing grape sugar to silver nitrate salts. These revolutionary lenses reflected up to 95% of the light, as opposed to the old bronze lenses, which reflected only 60% of the light. L. Foucault created reflectors with parabolic mirrors, changing the shape of the surface of the mirrors. In the late 19th century, Crossley, an amateur astronomer, turned his attention to aluminum mirrors. The 91 cm diameter concave glass parabolic mirror he bought was immediately inserted into the telescope. Today, telescopes with such huge mirrors are being installed in modern observatories. While the growth of the refractor slowed down, the development of the reflector telescope was gaining momentum. From 1908 to 1935, various observatories of the world built more than a dozen reflectors with a lens that exceeded the Yierks one. The largest telescope is installed at Mount Wilson Observatory, its diameter is 256 centimeters. And even this limit was very soon doubled. An American giant reflector has been installed in California; today it is more than fifteen years old.
More than 30 years ago, in 1976, Soviet scientists built a 6-meter BTA telescope - the Large Azimuthal Telescope. Until the end of the 20th century, the ARB was considered the world's largest telescope. The inventors of the BTA were innovators in original technical solutions, such as a computer-guided alt-azimuth installation. Today, these innovations are used in almost all giant telescopes. At the beginning of the 21st century, BTA was pushed aside to the second dozen large telescopes in the world. And the gradual degradation of the mirror from time to time - today its quality has dropped by 30% from the original - turns it only into a historical monument to science.
The new generation of telescopes includes two large telescopes - the 10-meter twins KECK I and KECK II for optical infrared observations. They were installed in 1994 and 1996 in the USA. They were collected thanks to the help of the W. Keck Foundation, after which they are named. He provided over $ 140,000 for their construction. These telescopes are about the size of an eight-story building and weigh more than 300 tons each, but they work with the highest precision. The main mirror, 10 meters in diameter, consists of 36 hexagonal segments that act as a single reflective mirror. These telescopes were installed in one of the most optimal places on Earth for astronomical observations - in Hawaii, on the slope of the extinct volcano Manua Kea with a height of 4,200 m. By 2002, these two telescopes, located at a distance of 85 m from each other, began to operate in the interferometer mode. giving the same angular resolution as an 85-meter telescope.
The history of the telescope has come a long way - from Italian glaziers to modern giant satellite telescopes. Modern large observatories have long been computerized. However, amateur telescopes and many Hubble devices are still based on the principles of work invented by Galileo.
