All types of telescopes are an instrument for collecting light and other rays coming from distant objects in the deep space. It may serve one of the several purposes like magnified viewing of an object, collection of rays emitted, detection of dark objects or areas etc. Developed in Netherlands in early 1600, it was continuously improved upon by Galileo, Sir Issac Newton and others along the way. By the early 20th century other telescopes were also developed such as radio telescopes and gamma-ray telescopes.
There are many types of telescopes according to their functions. Since the outer space sends us a variety of rays in the form of visible light and other rays like radio waves, x-rays, gamma rays and so forth, there are a number of telescopes for different purposes. We would be talking more about optical telescopes but here is a list of all types of telescopes in use currently with their uses.
- Infrared Telescopes, that rely on rays with wavelengths that in IR spectrum range
- X-ray Telescopes, that rely on rays with wavelengths that are shorter than the UV light
- Ultraviolet Telescopes, that rely on rays with wavelengths that lie in UV spectrum range
- X-ray Telescopes, used for capturing X-ray wavelengths rays coming from outer space
- Submillimeter Telescopes, that rely on rays with wavelengths that are longer than infrared light
- Optical Telescopes, that rely on visible light rays to show image of objects
We would be discussing optical telescopes in more details. An optical telescope does the job gathering visible light and magnifying it, so one can see the objects in space more closely which otherwise may not be visible to the naked eye. The optical telescopes have been around since 1609, and there are 3 main types of optical telescopes.
- Refracting Telescopes
- Reflecting Telescopes
- Catadioptric Telescopes
Refracting Telescopes – These are first telescopes that appeared in 1600’s, were subsequently improved upon by Galileo called Galileos’s telescope, Johannes Kepler and with the invention of Achromatic lenses and apochromatic refractors. It has the simplest of design and is still in use today for amateurs and as a spotting scope. Since these were the earliest of all types of telescopes, their main limitation lies in size and chromatic aberrations or color distortions. The lenses size also has a diametric limit and the telescopic lenses are opaque to some wavelengths of light and might contain air bubbles.
These telescopes work best in small sizes for hobbyists and beginner astronomers and are currently used as a telescope for kids, or beginner’s telescope, a spotting scope or even a rifle scope. Check out some Refractor telescopes here
Reflecting Telescopes – Plagued by limitations, reflecting telescopes succeeded refracting telescopes and overcame much of their limitations of size and chromatic aberrations. Though first conceptualizes in 1663 by James Gregory called Gregorian Telescope, Sir Issac Newton in 1668 made the first practical reflecting telescope which was fairly successful also called as Newtonian Telescope. It is the least expensive simple design for a reflecting telescope which results in a high-quality image. It has a wider field of view and can see deeper into space.
However, with Ritchey–Chrétien telescope design in the 1910s, freed the reflecting telescope of its primary limitations such as coma and spherical distortions caused by distortion in the glass forming the basis of many professional types of telescopes around the world today. Also, the images have a wider field of view and are of photographic quality. Check out some Reflector telescopes here
Catadioptric Telescopes – A catadioptric telescope is the best telescope which uses both the mirrors as well as lenses for optimum image clarity and magnification. This combination of lenses and mirrors is used with a corrector to produce a better distortion-free image with a wider field of view compared to other types of telescopes. These are generally better than all lenses or all mirrors telescope and are lighter in mass too. These are also called as compound telescopes.
The compound telescopes have a larger aperture, long focal length, are lightweight and significantly reduce coma found in reflecting telescopes with almost no chromatic distortions found in refracting telescopes. A setup and set down time of catadioptric telescope or compound telescope is minimal and allows for better fine tuning while viewing the night sky. Check out some Catadioptric telescopes (compound telescopes) here
Telescopes are our gateway to the external world that lies in obscurity, where much needs to be explored, where much explored is much more unexplored, into the world where infinity awaits existence and discovery.