Gregorian telescope
The Gregorian telescope is a type of
reflecting telescope designed by
Scottish mathematician and
astronomer, James Gregory in the
17th century.
He described the design in his 1663 publication
Optica Promota . Early attempts to build a Gregorian telescope failed, and it wasn't until ten years later, aided by the interest of experimental scientist
Robert Hooke, that a working instrument was actually constructed. Gregory's design pre-dates the familiar form of reflector which Sir
Isaac Newton first designed and made around 1670.
Encyclopedia
The
Gregorian telescope is a type of
reflecting telescope designed by
Scottish mathematician and
astronomer, James Gregory in the
17th century.
He described the design in his 1663 publication
Optica Promota . Early attempts to build a Gregorian telescope failed, and it wasn't until ten years later, aided by the interest of experimental scientist
Robert Hooke, that a working instrument was actually constructed. Gregory's design pre-dates the familiar form of reflector which Sir
Isaac Newton first designed and made around 1670.
The Gregorian telescope consists of two concave
mirrors; the primary mirror collects the light and brings it to a focus at the secondary mirror where it is reflected back through a hole in the centre of the primary, and thence out the bottom end of the instrument where it can be viewed with the aid of the eyepiece. This design of telescope renders an upright image, making it useful for terrestrial observations.
The Gregorian design has the advantage over Newton's design, in that it requires a shorter tube for the same
focal length. The design was largely superseded by the
Cassegrain telescope, and is not commonly in use today, other than for
spotting scopes.
See also
External links
