![]() ![]() ![]() Common telescopes which led to the Crossley and Harvard reflecting telescopes, which helped establish a better reputation for reflecting telescopes as the metal mirror designs were noted for their drawbacks. In the 19th century a new method using a block of glass coated with very thin layer of silver began to become more popular by the turn of the century. This type included Newton's first designs and the largest telescope of the 19th century, the Leviathan of Parsonstown with a 6 feet (1.8 m) wide metal mirror. Since reflecting telescopes use mirrors, the design is sometimes referred to as a catoptric telescope.įrom the time of Newton to the 1800s, the mirror itself was made of metal – usually speculum metal. Many variant forms are in use and some employ extra optical elements to improve image quality or place the image in a mechanically advantageous position. Almost all of the major telescopes used in astronomy research are reflectors. Although reflecting telescopes produce other types of optical aberrations, it is a design that allows for very large diameter objectives. The reflecting telescope was invented in the 17th century by Isaac Newton as an alternative to the refracting telescope which, at that time, was a design that suffered from severe chromatic aberration. Due to the usage of a high aperture mirror in reflecting telescopes, they have a very high-resolution power.Telescopes which utilize curved mirrors to form an image Stratospheric Observatory for Infrared Astronomy 24-inch convertible Newtonian/Cassegrain reflecting telescope on display at the Franklin InstituteĪ reflecting telescope (also called a reflector) is a telescope that uses a single or a combination of curved mirrors that reflect light and form an image. In refracting telescopes lenses are used which can cause chromatic aberration i.e., the formation of a colored image of a white object, which is not possible in reflecting telescopes as a mirror is used. Thus it reduces the cost of constructing a reflecting telescope over a refracting one. A mirror requires grinding and polishing of one of its surfaces only. Label the parts correctly as well.Īnother few advantages of a reflecting telescope over a refracting telescope: Make sure the diagram is clear with all its relevant parts. Note: A lot of times it is observed that while drawing ray diagrams students tend to double line a single ray due to frequent erasing and redrawing. (ii) The use of a paraboloidal mirror reduces the spherical aberration i.e., the phenomenon of formation of a non-point and blurred image of a point object. So even the faint or distant stars can be viewed easily. Thus the final image formed in the reflecting telescope is very bright. (i) A concave mirror of a large aperture has a high gathering power and absorbs a very less amount of light than the lenses of a large aperture. The following are two advantages of a reflecting telescope in comparison to a refracting telescope: The following diagram will clearly portray a reflecting telescope: The eyepiece is placed on the axis of the telescope near the hole of the primary mirror. There is a small convex (secondary mirror) near the focus of the primary mirror. It consists of a large paraboloidal (primary) concave mirror of a large focal length with a hole at its center. In 1668, the first reflecting telescope was constructed by Newton. It is constructed using an arrangement of lenses, or of curved mirrors and lenses, using these the rays of light are collected and focused and the resulting image is magnified in nature. Afterward, compare it with other refracting telescopes.Ī telescope is an optical instrument designed to see distant objects, as it makes them appear nearer. Students must draw a well labeled clear diagram for the telescope and then explain its working firstly. This telescope as the name suggests uses the principle of reflection also, so must consist of a reflecting mirror. Hint: Reflecting telescope is one that was constructed by Newton. ![]()
0 Comments
Leave a Reply. |
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |