Advances in astronomy are directly related to changing means of observation and our expanding understanding of the universe through the examination of the electromagnetic spectrum emitted by the objects of what’s often referred to as the “cosmic zoo.” The optical domain has traditionally preferred a body heated to temperatures of hundreds to thousands of degrees – that is the case for most of the planetary bodies and stars – emitting most of its radiation in the visible or near infrared parts of the spectrum. The implementation of large optical telescopes sensitive to these wavelengths is therefore imperative for astrophysical research.
Succeeding the instruments built in the 1970s and 1980s, a new generation of large ground optical telescopes came to be: The first one, the Keck-I, with an aperture of 8.2 m, was set in to service in May 1993 and was followed by many other instruments with openings of more than eight meters.
An optical telescope (from the Greek (tele) meaning ‘far’ and (skopein) meaning “look see”) is an optical instrument for increasing the brightness and the apparent size of objects to observe. The role as receiver of light is often more important than the magnification as it allows a glimpse of celestial objects visible or invisible hard spot with the naked eye.
These telescopes are mainly used in astronomy because their settings do not make it favorable for the observations of very distant objects and those moving relatively slowly.
A linguistic accuracy may be needed here because of possible confusion in the use and translation of the word telescope, especially when consulting documentation or manuals in English as this word refers to two types of optical telescope instruments:
* One, the “refracting optical telescope” means the telescope whose objective consists of a set of lenses, either only one term diopter (refractive)
* The other, “Reflecting telescope” means an observation device whose mirror (reflection) is a key component.
The telescope was designed in Italy in 1586; this invention is very likely due to the optician Giambattista della Porta. In August 21, 1609 the Italian astronomer Galileo presented at the top of the tower, the first telescope to the Doge Leonardo Donato and members of the Senate His fellow German Johannes Kepler perfected the principle by providing an optical two convex lenses.
Replica of the telescope 6 inch Isaac Newton presented to the Royal Society in 1672.
In a telescope, a concave mirror is used to form the image. In 1663, the Scottish mathematician James Gregory was the first to propose the formula of the telescope with a magnification due to the secondary. Nevertheless, Mersenne himself had anticipated a system in which primary and secondary were parabolic; the exit pupil was located on the secondary, which served as the eyepiece, but the field was very low.