Many of us simply love to look at the starry sky, admiring its stunning and alluring beauty. Of course, most of the people who are not indifferent to the stars are just romantics or lovers of lying in the field, inhaling the smell of fresh grass and counting white dots on a thick black surface with their loved one.
But there is another category of sky lovers. These individuals, as a rule, are scientists who admire the vault of heaven not with their own eyes or through glasses, but use special mirror telescopes to not only enjoy the beauty of the heavenly bodies, but also engage in scientific activities, calculating the necessary distances and extracting such an important for humanity information.
Optical instruments have not only been the best assistants of man in the study of distant planets for several millennia, but are simply indispensable in everyday life, since many peopleuse telescopes, binoculars and magnifiers for various purposes, without being aware of the original scientific purpose of these objects. Who among us has not made a fire with a magnifying glass? And who looked through the inverted binoculars? Everyone did this, which once again proves the vital need for people in lenses and magnifying glasses.
What is it?
A telescope - or, scientifically, a reflector - is a special optical device based on the principle of collecting light particles by a mirror plate. The very first mirror telescope was invented by the famous English mathematician Isaac Newton.
Yes, after him many different smart people offered their versions of the "far-sighted pipe". But it was Newton's direct lens that became the standard for almost all powerful optical instruments. Especially for those used in science and the military industry. The development of the English genius made it possible to get rid of chromatic aberration once and for all - the main and most inconvenient shortcoming of all telescopes of that time.
As an optical instrument, the reflex telescope is considered a relative of the spyglass and has a similar design, differing, however, in the size and quality of the lenses.
History of optics
The craving of humanity to observe objects or phenomena far from the eye arose long before the advent of large mirror telescopes. The scientific journey of the lens arose at the very moment when a person first looked at the world through a piece of mica, tilting it at the right angle so that the mineral could slightlybring the horizon closer.
Since then, mankind has been tirelessly looking for ways to achieve a similar effect. People actively invented frames, holders, polished mica, tried to work with quartz.
With the advent of glass, experiments on the invention of the “image zooming device” continued, as various defective pieces of material went into action, one way or another distorting space through themselves.
It took many years before humanity could construct the first mirror telescope. However, it is important to remember that the entire optical industry began with a tiny piece of mica.
Since the discovery of the composition of glass, man has ceased to need mica and quartz as substitutes or analogues of this wonderful substance. The first optical instruments created by man were rather simple designs like a magnifying glass or a monocle, i.e., a piece of glass artfully inserted into an iron frame.
England
In the field of mathematics and physics, this northern country has almost always been ahead of the entire planet on the path of its scientific development by centuries, if not thousands of years of progress. The whole world uses optical instruments thanks to the appearance in 1668 of Newton's mirror telescope. A genius from Foggy Albion proposed his vision of a "far-sighted pipe" using only two straight lenses. The main mirror is a light receiver, exposing itself to direct rays from some kind of illumination, and then transmitting the beam of light collected in one stream to a small flat diagonal mirror, whichlocated near the main focus. The task of this piece of one-sided glass is to deflect light outside the body of a mirror reflecting telescope. In this place, the interaction of the eyepiece and the image that falls into it, being reflected from the secondary diagonal glass, takes place, and is photographed. The type of built-in mirror directly depends on the diameter of the pipe - parabolic glass can be easily inserted into a casing with a large capacity, and spherical glass can also fit into a smaller tube.
Gregory's system
However, not only the discoverer of the force of gravity can be considered the inventor of the telescope, since the very fact that objects can be viewed through glass was studied long before the birth of Newton, there are many answers to the question of who invented the mirror telescope.
For example, Newton's countryman, James Gregory, in 1663 proposed his vision of a "far-sighted pipe", providing it with three glasses at once. The scheme of the proposed version was described by the scientist in the book Optica Promota, which also contains other wonderful ideas on the use of glass in everyday life.
The device of Gregory's first mirror telescope is quite simple at first glance. It is based on a concave parabolic mirror that collects disparate beams of light, combines them and directs them to a smaller concave elliptical mirror.
The small mirror in turn sends the light back to the center hole of the large glass that protects the eyepiece. Focal length of a mirror telescopeGregory is significantly larger than the Newtonian model, due to which the eye of the beholder sees a straight, even image, and not inverted 180 degrees, as in the previous model.
Cassegrain Idea
A similar system was proposed in 1672 by Laurent Cassegrain. Its development was also based on two mirrors of different diameters. However, Laurent preferred to work with direct reflection of light, reducing the whole design to the transmission of light beams between two glasses.
A distinctive feature of his telescope was the fact that the secondary mirror was much larger than the main one. Two hundred years later, this idea will be taken as a basis by the famous Soviet optician D. D. Maskutov, who will lay the fundamental foundations of the Russian science of optical instruments, and also invent the main model of the telescope, which will become the basis for all instruments related to image approximation in the Soviet Union. Union.
The following systems, similar to the Ritchie-Chrétien design, are just supplemented and corrected versions of Cassegrain's ideas.
Lomonosov's innovation
The only exception is Herschel's optical theory, which at one time was significantly improved by the brilliant Russian encyclopedist Mikhail Lomonosov. The essence of the idea is that the main glass was replaced with a concave mirror.
What is a telescope for?
Everyone knows that devices for studying the celestial surface are mainly used by astronomers and other scientists who, based on the data obtained, draw conclusions globallyaffecting various branches of science. Such disciplines as geography, geodesy, biology, biophysics and many others depend on astronomy. Even a regular weather forecast is almost impossible to make. Not having received timely data on the location of celestial bodies relative to the sun.
A telescope is needed in order to directly observe various objects and phenomena that may turn out to be crucial for science and for humanity as a whole. Instruments of different sizes, with significantly different characteristics, are used both for ordinary viewing of the night sky and for penetrating the secrets of distant nebulae and galaxies.
The biggest appliances
Currently, there are a huge number of different technological devices that allow you to explore the starry sky. Most of them are simply incredible in size and occupy a huge area. For example, the largest telescope in the Soviet Union, BTA, was for a long time considered the largest in the world, as it had a main mirror diameter of as much as six meters!
In 2005, an even larger explorer of celestial bodies was built - an instrument called the Large Binocular Telescope. It differs in that its mirror is solid, that is, it consists of one piece of glass.
In the same year, the "Large South African Telescope" was erected in the Republic of South Africa, the main mirror of which consisted of ninety-one huge identical hexagons.
Device device
The optical mirror telescope has a fairly simple structure. Any student can independently create a similar device with only one or two lenses and a hollow cardboard tube. Of course, real powerful devices are not made of glass and paper, but according to a similar principle.
The device is a closed system, which is based on a solid hollow tube, with lenses of various types and structures inserted into it at both ends. The rear plane of the first glass is aligned with the front plane of the second, which gives the effect of zooming in on an image that is actually far from the observer.
Reviews
How to choose a good telescope? This question is easy to answer if you know exactly how the buyer will use it. If a person is just interested in seeing the starry sky a little closer, then any budget model for beginners will do. If the person who wants to purchase the device is an astronomer, even if he is an amateur, but still an astronomer, then you should think about purchasing a more expensive analogue.
In the case when science and research is dear to the future owner of the telescope, it is worth recognizing that a professional device is needed, which is very expensive. There are no specific tips for choosing a telescope, you just need to clearly understand why you are choosing it!
