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133:. Using a monolithic mirror much larger than 5 meters is prohibitively expensive due to the cost of both the mirror, and the massive structure needed to support it. A mirror beyond that size would also sag slightly under its own weight as the telescope was rotated to different positions, changing the precision shape of the surface. Segments are also easier to fabricate, transport, install, and maintain over very large monolithic mirrors.
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232:(SALT) is a 10-meter telescope dedicated on spectroscopy for most of its observing time. It shares similarities with the Hobby-Eberly Telescope and also consists of 91 hexagonal mirror segments, each 1 meter across, resulting in a total hexagonal mirror of 11.1 m by 9.8 m. It is located close to the town of
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at an altitude of 2,026 m (6,647 ft). Its primary mirror is constructed from 91 hexagonal segments. The telescope's main mirror is fixed at a 55 degree angle and can rotate around its base. A target is tracked by moving the instruments at the focus of the telescope; this allows access to about 70–81%
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with segmented mirrors also exhibit diffraction spikes due to diffraction from the mirrors' edges. As before, two spikes are perpendicular to each edge orientation, resulting in six spikes (plus two fainter ones due to the spider supporting the secondary mirror) in photographs taken by the
136:
Segmented mirrors do have the drawback that each segment may require some precise asymmetrical shape, and rely on a complicated computer-controlled mounting system. All of the segments also cause
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during the 1980s, and since then all the necessary technologies have spread worldwide to the point that essentially all future large optical telescopes plan to use segmented mirrors.
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82:, who built the first working segmented mirror in 1952, after twenty years of research; It was later independently rediscovered and further developed under the leadership of
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can not be constructed larger than about eight meters in diameter. The largest monolithic mirrors in use are currently the two primary mirrors of the
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of China. It consists of two rectangular mirrors, made up of 24 and 37 segments, respectively. Each hexagonal segment is 1.1 metre in size.
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Bonoli, F. "Guido Horn d'Arturo and the first multi-mirror telescopes: 1932-1952." Memorie della
Societa Astronomica Italiana 89 (2018): 448.
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is to be built at the Mauna Kea
Observatories in Hawaii, though construction is on hold. This will use 492 hexagonal segments. The
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will be the largest of all three, using a total of 798 segments for its primary mirror. Its first light is expected for 2027.
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129:, each with a diameter of 8.4 meters. The use of segmented mirrors is therefore a key component for large-aperture
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There is a technological limit for primary mirrors made of a single rigid piece of glass. Such non-segmented, or
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will be the next generation of segmented-mirror telescopes and are planned to be commissioned in the 2020s. The
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sector to minimize the size of the optical components. A partial reflective segmented mirror array is used by
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Edges of the JWST primary mirror segments and spider colour-coded with their corresponding diffraction spikes
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uses a total of 36 segmented mirrors. With a primary mirror of 10.4 m (34 ft), it is currently the
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in the world use segmented primary mirrors. These include, but are not limited to the following telescopes:
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uses seven large segments and is either grouped with segmented mirrors telescopes or its own category. The
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of the sky at its location and a single target can be tracked for up to two hours.
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199:, United States. Both telescopes feature 10 m (33 ft) primary mirrors.
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836:"ESO's Extremely Large Telescope planned to start scientific operations in 2027"
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to out-couple the light from their light guides, which is used as an optical
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is an array of smaller mirrors designed to act as segments of a single large
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at an elevation of 4,145 meters (13,600 ft) near the summit of
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Early segmented mirror, built out of 61 hexagonal segments in 1952.
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Array of smaller mirrors designed to act as one large curved mirror
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to a precise shape and actively aligned by a computer-controlled
696:"Revolution in telescope design debuts at Keck after birth here"
281:
196:
143:
Another application for segmented mirrors can be found in the
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812:"NASA Readies James Webb Space Telescope for December Launch"
237:
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368:
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858:"James Webb: 'Fully focused' telescope beats expectations"
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The Keck II telescope showing the segmented primary mirror
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642:"The endless mantra: Innovation at the Keck Observatory"
211:(HET) is a 9.2-meter (30-foot) telescope located at the
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158:
244:, the national optical observatory of South Africa.
148:
886:. Springer Science+Business Media. pp. 61–72.
798:"Six JWST Mirror Segments to Begin Cryogenic Tests"
223:
63:. To function, all the mirror segments have to be
498:The first JWST deep field with diffraction spikes
972:
882:. In Foy, Renaud; Foy, François-Claude (eds.).
619:"Keck telescope science kit fact sheet, Part 1"
540:List of largest optical reflecting telescopes
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51:or asymmetric (if they are part of a larger
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591:
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751:Southern African Large Telescope website
240:, South Africa. It is a facility of the
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18:
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640:Bobra, Monica Godha (September 2005).
242:South African Astronomical Observatory
71:system using actuators built into the
786:Giant telescope begins scouring space
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621:. SCI Space Craft International. 2009
471:Diffraction spike § Segmented mirrors
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284:is a survey telescope located in the
88:Lawrence Berkeley National Laboratory
592:Nickerson, Colin (5 November 2007).
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300:were mostly fabricated in 2011. The
23:Size comparison of primary mirrors.
13:
427:European Extremely Large Telescope
402:European Extremely Large Telescope
262:Roque de los Muchachos Observatory
260:optical telescope, located at the
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159:Telescopes using segmented mirrors
14:
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773:Tests begin on Canaries telescope
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252:Also known as the GranTeCan, the
236:in the semi-desert region of the
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800:news.softpedia.com 14 April 2011
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510:JWST image of the spiral galaxy
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469:This section is an excerpt from
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367:Segment after being coated with
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230:Southern African Large Telescope
224:Southern African Large Telescope
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810:Margetta, Robert (2021-09-08).
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702:. Lawrence Berkeley Laboratory
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296:The 18 mirror segments of the
187:are the most prominent of the
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1:
880:"Segmented Mirror Telescopes"
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78:The concept was pioneered by
47:. The segments can be either
981:Optical telescope components
694:Yarris, Lynn (Winter 1992).
140:effects in the final image.
7:
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10:
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484:James Webb Space Telescope
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390:extremely large telescopes
381:
378:Next-generation telescopes
320:James Webb Space Telescope
298:James Webb Space Telescope
292:James Webb Space Telescope
165:largest optical telescopes
545:Cherenkov Telescope Array
384:Extremely large telescope
275:
127:Large Binocular Telescope
455:Giant Magellan Telescope
394:Giant Magellan Telescope
334:Mirror segments made of
254:Canaries Great Telescope
248:Gran Telescopio Canarias
92:University of California
514:with diffraction spikes
318:Mirror segments of the
189:Mauna Kea Observatories
884:Optics in Astrophysics
878:Nelson, Jerry (2005).
675:Cite journal requires
441:Thirty Meter Telescope
398:Thirty Meter Telescope
312:on December 25, 2021.
209:Hobby-Eberly Telescope
203:Hobby-Eberly Telescope
180:
118:
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36:
647:. MIT. Archived from
410:Conceptual images of
382:Further information:
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113:
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61:reflecting telescopes
22:
700:Science@Berkeley Lab
563:W. Patrick McCray -
213:McDonald Observatory
55:). They are used as
722:"tooz technologies"
310:Guiana Space Centre
304:was launched by an
117:'s segmented mirror
80:Guido Horn D'Arturo
73:mirror support cell
53:parabolic reflector
594:"Long time no see"
464:Diffraction spikes
181:
123:monolithic mirrors
119:
108:
37:
31:and arranged in a
893:978-1-4020-3437-4
747:"Mirror Segments"
264:on the island of
145:augmented reality
25:Segmented mirrors
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864:. 16 March 2022.
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84:Dr. Jerry Nelson
41:segmented mirror
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185:Keck Telescopes
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171:Keck Telescopes
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838:. 11 June 2021
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677:|journal=
654:on 5 June 2011
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27:are typically
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69:active optics
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45:curved mirror
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965:Solar System
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840:. Retrieved
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819:. Retrieved
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788:14 July 2007
781:
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755:. Retrieved
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730:. Retrieved
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704:. Retrieved
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668:cite journal
656:. Retrieved
649:the original
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623:. Retrieved
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601:. Retrieved
598:Boston Globe
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477:Images from
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163:Some of the
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24:
953:Outer space
941:Spaceflight
728:(in German)
706:11 November
658:11 November
625:11 November
603:11 November
138:diffraction
98:Application
975:Categories
821:2021-09-15
732:2022-01-26
567:- Page 107
551:References
479:telescopes
272:in Spain.
234:Sutherland
217:West Texas
153:smartglass
131:telescopes
59:for large
57:objectives
917:Astronomy
350:Cryogenic
336:beryllium
268:, in the
193:Mauna Kea
183:The twin
155:element.
49:spherical
33:honeycomb
29:hexagonal
862:BBC News
534:See also
512:NGC 7469
306:Ariane 5
266:La Palma
65:polished
35:pattern.
986:Mirrors
903:Portals
842:18 June
86:at the
890:
757:10 May
753:. SOAA
388:Three
276:LAMOST
197:Hawaii
929:Stars
652:(PDF)
645:(PDF)
308:from
238:Karoo
888:ISBN
844:2021
816:NASA
759:2013
726:Tooz
708:2009
681:help
660:2009
627:2009
605:2009
412:ELTs
369:gold
354:MSFC
280:The
228:The
207:The
149:tooz
115:SALT
90:and
195:in
977::
860:.
814:.
749:.
724:.
698:.
672::
670:}}
666:{{
596:.
573:^
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39:A
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679:(
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