Refractor Telescopes
The most basic refractor telescopes include a long hollow tube with a primary lens to refract light from an object. These are often great telescopes for kids. Refraction is different from reflection in the sense that reflection is more of a direct mirroring effect. The primary lens works like a prism in the refractor telescopes. Light waves coming from an object at a distance enter the lens and then bend according to the focal length.
Initially, the refractor telescopes were built with low magnification and the invention was credited to Hans Lippershey. However, there were several other people in Europe building similar telescopes. Therefore, the first refractor telescopes were used for entertainment and at circus, sports or theater shows. Soon, the refractor telescopes began being used in the military and therefore, greater emphasis was placed on accuracy and improvements in the basic model.
Italy was one of the first European nations to have refractor telescopes designed by Galileo Galilei. Galilei improved upon the basic design to a fantastic degree and used both concave and convex mirrors.
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Another inventor, Johannes Kepler, who was also a friend of Galilei further improved the design and used convex lens for viewing at both ends of the basic refractor telescopes. Galilei's telescope had a limited field of view. Also, the distance between the eye and the eyepiece helped improve the comfort level for the viewer for extended use. However, the refractor telescopes needed to be inconveniently long for better magnification.
The refractor telescopes also had spherical problems. This problem could only be rectified by impractical lengths of telescope. Nearly a century later, Chester Moore Hall used two different objective lenses to improve upon the image. These lenses were made of silicates of alkali-lime and had very low refractive index. The polishing of these lenses enhanced the image to a great extent and reduced the problem of telescope length. Successive refractor telescopes were built by John Dollond and other engineers.
Only quality of lenses used has improved over the years but the overall design of the refractor telescopes has remained the same. These telescopes can be used for all kinds of applications from terrestrial to celestial ones. Refractor telescopes are extremely popular with travelers too apart from astronomy students.
Most people today prefer refractor telescopes to reflector telescopes because of greater utility and a more precise image. The technology and design of refractor telescopes is also used in high-quality binoculars most spectators try during international sports events. Cameras can also be attached to refractor telescopes.
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