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curvature of the tertiary is placed directly at the vertex of the secondary mirror, then the
Schmidt plate would lie on top of the paraboloid secondary mirror. Therefore, the Schmidt plate required to make the tertiary mirror a Schmidt telescope is eliminated by the paraboloid figuring on the convex secondary of the Mersenne system, as each corrects the same magnitude of spherical aberration, but the opposite sign. Also, as the system of Mersenne + Schmidt is the sum of two anastigmats (the Mersenne system is an anastigmat, and so is the Schmidt system), the resultant system is also an anastigmat, as third-order aberrations are purely additive. In addition the secondary is now easier to fabricate. This design is also called a
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on the same mirror. In one option the tertiary is identical to the primary, whereas the second option shows the tertiary as polished into the primary mirror. The
Eisenberg-Pearson telescope does not require a flat fold mirror to allow access to the image plane since the focal plane is located behind the secondary mirror. A compact illustration of the Korsch telescope published in 1995 by Shai Eisenberg is the solid version of the design with the use of
20:
184:
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A variation of the Korsch design is the Two-Mirror three-surface telescope introduced by Shai
Eisenberg and Earl T. Pearson in 1987. Employing the Korsch equations with minimal modifications, the number of mirrors is reduced from three to two by combining the primary surface and the tertiary surface
118:
One way to look at this is to imagine the tertiary mirror, which suffers from spherical aberration, is replaced by a
Schmidt telescope, with a correcting plate at its centre of curvature. If the radii of the secondary and tertiary are of the same magnitude, but opposite sign, and if the centre of
82:
Many combinations of three mirror figures can be used to cancel all third-order aberrations. In general these involve solving a relatively complicated set of equations. A few configurations are simple enough, however, that they could be designed starting from a few intuitive concepts.
95:
spherical aberration – no coma or astigmatism (but they do produce an image on a curved surface of half the radius of curvature of the spherical mirror). So if the spherical aberration can be corrected, a very wide field of view can be obtained. This is similar to the conventional
58:, will always have aberrations. If the mirror is spherical, it will suffer from spherical aberration. If the mirror is made parabolic, to correct the spherical aberration, then it must necessarily suffer from coma and off-axis astigmatism. With two curved mirrors, such as the
115:, with both the input and output beams collimated. The compressed input beam is then directed to a spherical tertiary mirror, which results in traditional spherical aberration. Paul's key insight is that the secondary can then be converted back to a spherical mirror.
304:, formerly named the Wide Field Infrared Survey Telescope (WFIRST), employs a folded three-mirror anastigmat featuring an ellipsoidal primary, hyperboloidal secondary, and ellipsoidal tertiary. An earlier design used an off-axis three-mirror anastigmat.
23:
Three-mirror anastigmat of Paul or Paul–Baker form. A Paul design has a parabolic primary with spherical secondary and tertiary mirrors; a Paul–Baker design modifies the secondary slightly to flatten the focal
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509:
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The first were proposed in 1935 by
Maurice Paul. The basic idea behind Paul's solution is that spherical mirrors, with an aperture stop at the centre of curvature, have
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across the wide field of view. However, the astigmatism can be reduced by including a third curved optical element. When this element is a mirror, the result is a
445:
Korsch, Dietrich (December 1972). "Closed form solution for three-mirror telescopes, corrected for spherical aberration, coma, astigmatism, and field curvature".
62:, coma can be minimized as well. This allows a larger useful field of view, and the remaining astigmatism is symmetrical around the distorted objects, allowing
383:
139:. The Paul–Baker design adds extra spacing and reshapes the secondary to elliptical, which corrects field curvature to flatten the focal plane.
248:'s telescope (formerly known as Large Synoptic Survey Telescope) is an Eisenberg-Pearson design with an additional refractive corrector.
51:. This is primarily used to enable wide fields of view, much larger than possible with telescopes with just one or two curved surfaces.
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59:
584:"Optical design and predicted performance of the WFIRST phase-b imaging optics assembly and wide field instrument"
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Shai
Eisenberg and Earl T. Pearson "Two- Mirror three-surface telescope"., Proc SPIE Vol. 751, p24, January 1987.
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is a three-mirror anastigmat featuring an ellipsoidal primary, hyperboloidal secondary, and ellipsoidal tertiary.
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project includes a 100 mm working model built in 1985 and a 500 mm prototype built in 1986.
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built with three curved mirrors, enabling it to minimize all three main optical aberrations –
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647:"Optical design trade study for the Wide Field Infrared Survey Telescope [WFIRST]"
510:"Optical design and analysis of the James Webb Space Telescope: Optical telescope element"
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Earth observation satellites both carry a three-mirror anastigmat Korsch design telescope.
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UV/Optical/IR Space
Telescopes and Instruments: Innovative Technologies and Concepts V
512:. In Sasian, Jose M.; Koshel, R. John; Manhart, Paul K.; Juergens, Richard C. (eds.).
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259:) telescopes may be a three-mirror anastigmat, since the spare telescopes given to
123:, since it uses a Mersenne configuration as the corrector for a Schmidt telescope.
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Paul, Maurice (May 1935). "Systèmes correcteurs pour réflecteurs astronomiques".
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will be a three-mirror anastigmat design, with two additional flat fold mirrors.
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Content, D.A.; Goullioud, R.; Lehan, J.P.; Mentzell, J.E. (14 September 2011).
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Paul's idea was to start with a
Mersenne beam compressor, which looks like a
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552:"DEIMOS‑2: Costeffective, Very-high Resolution Multispectral Imagery"
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A more general set of solutions was developed by
Dietrich Korsch in 1972. A
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Baker, J.G. (1969). "On improving the effectiveness of large telescopes".
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135:, but this was corrected in the Paul–Baker design, introduced in 1969 by
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656:. Conference Proceedings of the SPIE. Vol. 8146. pp. 81460Y.
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586:. In Thibault, Simon; Mahajan, Virendra N.; Johnson, R. Barry (eds.).
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and can have a wide field of view while ensuring that there is little
74:, used to bend the optical path into more convenient configurations.
36:
19:
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516:. Conference Proceedings of the SPIE. Vol. 5524. p. 30.
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Current
Developments in Lens Design and Optical Engineering XIX
204:(TIR) to integrate the fourth fold mirror without introducing
70:. In practice, the design may also include any number of flat
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Contreras, James W.; Lightsey, Paul A. (22 October 2004).
424:"Paul-Baker and other three-mirror anastigmatic aplanats"
652:. In MacEwen, Howard A.; Breckinridge, James B. (eds.).
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Yeshayahu S. Eisenberg USP 5,930,055 "Lens Apparatus"
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IEEE Transactions on Aerospace and Electronic Systems
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Pasquale, Bert A.; et al. (17 September 2018).
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design, but the Schmidt does this with a refractive
54:A telescope with only one curved mirror, such as a
514:Novel Optical Systems Design and Optimization VII
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237:"Cambridge University Three-Mirror Telescope"
187:Eisenberg – Pearson Two-mirror Three-surface
335:Revue d'Optique Théorique et Instrumentale
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569:"Technical Specifications of DubaiSat 2"
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131:Paul's solution had a curved
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257:Future Imagery Architecture
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179:Eisenberg-Pearson telescope
104:instead of a third mirror.
16:Reflecting telescope design
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422:Sacek, V. (14 July 2006).
222:James Webb Space Telescope
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60:Ritchey–Chrétien telescope
272:Extremely Large Telescope
246:Vera C. Rubin Observatory
202:total internal reflection
111:made from two (confocal)
401:10.1109/TAES.1969.309914
291:imaging spectrometer on
231:uses a Korsch telescope.
315:List of telescope types
68:three-mirror anastigmat
30:three-mirror anastigmat
426:. Telescope-Optics.net
387:. AES-5 (2): 261–272.
352:Wilson, R. N. (2007).
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469:10.1364/AO.11.002986
153:spherical aberration
127:Paul–Baker telescope
41:spherical aberration
662:2011SPIE.8146E..0YC
596:2018SPIE10745E..0KP
522:2004SPIE.5524...30C
461:1972ApOpt..11.2986K
393:1969ITAES...5..261B
137:James Gilbert Baker
56:Newtonian telescope
604:10.1117/12.2325859
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670:10.1117/12.898528
530:10.1117/12.559871
455:(12): 2986–2987.
367:978-3-540-40106-3
283:DubaiSat‑2
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169:stray light
161:astigmatism
133:focal plane
113:paraboloids
49:astigmatism
321:References
297:spacecraft
206:vignetting
109:Cassegrain
64:astrometry
34:anastigmat
632:126155297
538:120352992
430:13 August
37:telescope
701:Category
688:30254738
477:20119447
409:51647158
358:Springer
309:See also
215:Examples
658:Bibcode
592:Bibcode
518:Bibcode
457:Bibcode
389:Bibcode
263:by the
171:in the
98:Schmidt
78:History
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163:, and
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32:is an
24:plane.
684:S2CID
650:(PDF)
628:S2CID
555:(PDF)
534:S2CID
405:S2CID
289:Ralph
618:ISBN
473:PMID
432:2013
362:ISBN
300:The
281:and
277:The
270:The
261:NASA
251:The
244:The
234:The
227:The
220:The
157:coma
93:only
45:coma
674:hdl
666:doi
608:hdl
600:doi
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