The Chinese Future Giant Telescope is a proposed

optical telescope An optical telescope gathers and focus (optics), focuses light mainly from the visible spectrum, visible part of the electromagnetic spectrum, to create a magnification, magnified image for direct visual inspection, to make a photograph, or to co ...

with a

primary mirror A primary mirror (or primary) is the principal light-gathering surface (the objective) of a reflecting telescope. Description The primary mirror of a reflecting telescope is a spherical, parabolic, or hyperbolic shaped disks of polished ...

that has a 30-meter diameter.

Major characteristics

The Chinese Future Giant Telescope has a primary

focal ratio An f-number is a measure of the light-gathering ability of an optical system such as a camera lens. It is calculated by dividing the system's focal length by the diameter of the entrance pupil ("clear aperture").Smith, Warren ''Modern Optical ...

of 1.2. Its primary mirror is segmented with 1020 annular submirrors arranged in 17 concentric annuli. Each segment has average length and width both of 0.8 m. Apart from a conventional

Cassegrain focus The Cassegrain reflector is a combination of a primary concave mirror and a secondary convex mirror, often used in optical telescopes and radio antennas, the main characteristic being that the optical path folds back onto itself, relative to the ...

, four Nasmyth foci on two double-deck platforms on both sides are also present. There is a Coudé focus provided for there interferometric array. The comparatively small secondary mirror is 2.74 m in diameter, which will serve active corrections. Other characteristics include: #Partial annular submirrors #One of coude planar mirrors is aspherical; better image quality is obtained from such a system. #A pair of lens-prisms are used in a wide field of view system. Better image quality is obtained and atmospheric dispersion is corrected.

Major characteristics

See also

References

Further reading