Optical Telescopes Introduction

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Optical Telescopes Introduction

The night sky always attracted people by its charming mystery. Observers had been using naked eyes for their explorations for many centuries. Obviously, they could not achieve a lot due to eyesight limitations. It cannot be estimated, how important the invention of telescopes was for astronomers. It opened an enormous field for visual observations, which had lead to many brilliant discoveries. That happened in 1608, when the German-born Dutch eyeglass maker had guessed to combine several lenses and created the first telescope [PRAS]. This occasion is now almost forgotten, because no inventions were made but a Dutchman. His device was not used for astronomical purposes, and it found its application in military use. The event, which remains in people memories, is the Galilean invention of his first telescope in 1609. The first Galilean optical tube was very simple, it could only magnify objects three times. After several modifications, the scientist achieved higher optical power. This helped him to observe the venusian phases, lunar craters and four jovian satellites. The main tasks of a telescope are the following:

• Gathering as much light radiation as possible

• Increasing an angular separation between objects

• Creating a focused image of an object We have now achieved high technical level, which enables us to create colossal telescopes, reaching distant regions of the Universe and making great discoveries.

Telescope components

The main parts of which any telescope consists with are the following:

• Primary lens (for refracting telescopes), which is the main component of a device. Bigger the lens, more light a telescope can gather and fainter objects can be viewed.

• Primary mirror (for reflecting telescopes), which carries the same role as the primary lens in a refracting telescopes.

• Eyepiece, which magnifies the image.

• Mounting, which supports the tube, enabling it to be rotated. Telescopes can be divided into two main categories: refractors and reflectors.

Refracting telescopes

The history of refractor’s invention was discussed in the introduction part. Refractor is the simplest type of telescopes, which combines two lenses at the ends of a tube. As mentioned above, the main component of this type of

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telescope is the primary lens – the objective. A concave lens is used as an objective of a refractor. It defines how faint objects ...