An optical telescope collects and magnifies visible part of the electromagnetic waves for the purpose of seeing the magnified image of the object, to take photograph and to collect data. An optical telescope is a telescope which is used to gather and focus light, for directly viewing a magnified image, making a photograph, etc.
There are mainly three types of optical telescopes, viz –
(1) Refracting: Lens is used.
(2) Reflecting: Mirror is used.
(3) Catadioptric: Both lens and mirrors are used.
Optical telescopes are used in astrophysics, ornithology, to know the position of the enemy etc. The term is used especially for a monocular with static mounting for observing the sky.
There are three major types of optical telescopes, classified according to the element that gathers and focuses the incoming light. In the refracting telescope, or refractor, light is bent, or refracted, as it passes through an objective lens.
Principle of operation
In coming days in the optical telescope are collected by the object lens and sent inside the telescope. Accumulation of rays is done by the object lens (convex lens or concave mirror) placed before the telescope. Rays coming from long distance meet at a point on the focal plane and form a real image of the object. This image is magnified by the eye lens and is incident on the eyes and form magnified real image of the object. Here eye lens acts like a magnifying glass. This is the principle of the optical telescope.