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Telescopes can be classified by optical design or mechanical design/construction. Telescopes can also be classified by where they are placed, such as space telescopes. One major determining factor is type of light, or particle being observed including devices referred to as "telescopes" that do not form an image or use optics.
Alvan Clark & Sons made the 36-inch (910 mm) objective lens for the Lick Observatory refractor, shown here in an 1889 drawing. The telescope was designed and built by the Warner & Swasey Company Alvan Clark & Sons was an American maker of optics that became famous for crafting lenses for some of the largest refracting telescopes of the 19th and ...
The refracting telescope which uses lenses to form an image. [27] The reflecting telescope which uses an arrangement of mirrors to form an image. [28] The catadioptric telescope which uses mirrors combined with lenses to form an image. A Fresnel imager is a proposed ultra-lightweight design for a space telescope that uses a Fresnel lens to ...
A simple example of an afocal optical system is an optical telescope imaging a star, the light entering the system is from the star at infinity (to the left) and the image it forms is at infinity (to the right), i.e., the collimated light is collimated by the afocal system. [2]
The Large Binocular Telescope at the Mount Graham International Observatory in Arizona uses two curved mirrors to gather light. An optical telescope is a telescope that gathers and focuses light mainly from the visible part of the electromagnetic spectrum, to create a magnified image for direct visual inspection, to make a photograph, or to collect data through electronic image sensors.
Galileo's objective lens. Galileo's objective lens is a specific objective lens held in the Museo Galileo, Florence, Italy. It was used by Galileo Galilei in the Galilean telescope with which he discovered the four largest moons of Jupiter in 1610. The lens has a diameter of 38mm and a gilt brass housing.
1611 — Johannes Kepler describes the optics of lenses (see his books Astronomiae Pars Optica and Dioptrice), including a new kind of astronomical telescope with two convex lenses (the 'Keplerian' telescope). 1616 — Niccolo Zucchi claims at this time he experimented with a concave bronze mirror, attempting to make a reflecting telescope.
A refracting telescope commonly used is the Galilean telescope which can function as a simple beam expander for collimated light. The main advantage of the Galilean design is that it never focuses a collimated beam to a point, so effects associated with high power density such as dielectric breakdown are more avoidable than with focusing ...