Hobbies And Interests
Basics
The reflective telescope is another type of the many telescopes in the world. This type of telescope forms the initial image you see through the telescope by a concave mirror. The concave mirror is used to focus in on light by reflecting the light inward to one focal point.
Function
While this telescope uses high intensity light on the surface of the mirror, it is primarily used to view distant objects like moons, planets and comets. Although smaller versions have been built to use in your home, they are normally large and found in astronomy laboratories, generally in the middle of the room because of its massive size. Astronomers use the telescope on a daily basis for their studies.
History
Sir Isaac Newton invented the reflecting telescope in the late 1600s. His detailed idea was presented to the Royal Society in 1670, but the process of the invention did not become public until 1700 when his treatise "Opticks" was published. The idea of using a mirror in the telescope rather than a lens made his invention unique.
Mirrors and Lenses
The main difference between a refracting telescope and a reflecting telescope is that the refracting one uses lenses. The advantages that mirrors have on lenses are the reasons why reflecting telescopes are the more ideal telescope to use. According to Telescopemaking.org, "The angle of reflection does not depend on the wavelength of light like the angle of refraction does because the mirrors are perfectly achromatic." Reflecting telescopes are free from color errors, which usually affect refracting telescopes. Other advantages include that the mirrors do not have to be made from expensive optical glass. Refractor instruments are required to use a homogeneous, pure and free from bubbles glass. Only the surface of the mirror matters in reflective telescopes. With the mirror, it solely needs to be polished and kept clean while a refractive telescope can have from two to four lenses that need maintenance attention.
Types of Mirrors
Two types of mirrors that are used for reflective telescopes are the primary mirror and the flat mirror (also called the diagonal). Newtons' first mirror was made out of metal and was two inches in diameter. Most modern telescopes are now made out of glass, quartz or glass/ceramic composites. The primary mirror displays a concave shape which enables it to magnify its objects. An astronomer would usually place an eyepiece in front of the image that is shown in the primary mirror, and would use the eyepiece to magnify and focus in on the image. The diagonal mirror is very flat and is used to intercept the cone of light prior to the focus, and sends the light out towards the side of the tube where the eyepiece can magnify the image.