Abstract

The concepts of a new major but medium-sized solar telescope are described. Located at one of the finest astronomical sites, La Palma, the telescope uses a doublet lens as the image forming element to minimize the number of reflecting surfaces, antireflection coatings to minimize stray light, and a separate guiding telescope outside the aperture of the telescope to avoid image degradation due to diffraction effects. Mechanically, the telescope uses the Sacramento Peak turret design which produces a minimum of local seeing effects. A short spectrograph, designed for minimum scattered light along and perpendicular to the slit, is also described. In several respects the telescope is different from other recently constructed or planned solar telescopes.

© 1985 Optical Society of America

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References

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  1. W. C. Livingston et al., “Kitt Peak 60-cm Vacuum Telescope,” Appl. Opt. 15, 33 (1976).
    [CrossRef] [PubMed]
  2. J. P. Mehltretter, “The Fraunhofer Institute Vacuum Tower Telescope for Roque de los Muchachos,” Joint Organization for Solar Observations Annual Report (1975), p. 36.
  3. E. H. Schröter, “Facilities of the Locarno Station of the Gottingen Observatory,” Joint Organization for Solar Observations Annual Report (1975), p. 28.
  4. C. Kühne, “The Concept of the New 60 cm Domeless Solar Telescope at Hida Observatory,” Osservazione e Memoire dell Osservatorio Astrofisico di Arcetri, Fasciolo, 106 (1978), p. 53.
  5. Y. Nakai, in Proceedings, Japan-France Seminar on Solar Physics, F. Moriyama, J. Henoux, Eds. (1981), p. 275.
  6. R. B. Dunn, “High Resolution Solar Observations,” Space Res. 12, 1657 (1972).
  7. S. Koutchmy, “Photospheric Faculae: The Contrast at the Center of the Solar Disk Using Filigree Pictures,” Astron. Astrophys. 61, 397 (1977).
  8. R. B. Dunn, “An Evacuated Tower Telescope,” Appl. Opt. 3, 1353 (1964).
    [CrossRef]
  9. R. B. Dunn, “Sacramento Peak’s New Solar Telescope,” Sky Telesc. 38, 368 (1969).
  10. R. B. Dunn, Sacramento Peak Observatory; private communication.
  11. U. Kusoffsky, Swedish Astrophysics Research Station on La Palma; private communication.
  12. D. S. Brown, “Optics for the 50 cm Vacuum Telescope,” in Technical Report of the Swedish Astrophysics Research Station on La Palma (1985).
  13. H. Sönnerlind, Dept. of Strength of Materials and Solid Mechanics, Stockholm; private communication.
  14. K. Bahner, “Teleskope,” in Handbuch der Physik, S. Flugge, Ed. (Springer-Verlag, Berlin, 1967), Vol. 29, p. 245.
  15. J. P. Mehltretter, “On Thermal-Optical distortions of Glass Disks,” J. Opt. 10, 93 (1979).
    [CrossRef]
  16. J. P. Mehltretter, “Window for Vacuum Telescopes: Review of Problem Areas,” in Large European Solar Telescope: Report on a Study for the Joint Organization for Solar Observations (1981), Appendix D, p. 199.
  17. R. Muller, Observatoires du Pic du Midi; private communication.
  18. A. A. Wyller, T. Fay, “URSIES: an Ultravariable Resolution Single Interferometer Echele Scanner,” Appl. Opt. 11, 1152 (1972).
    [CrossRef] [PubMed]

1979 (1)

J. P. Mehltretter, “On Thermal-Optical distortions of Glass Disks,” J. Opt. 10, 93 (1979).
[CrossRef]

1977 (1)

S. Koutchmy, “Photospheric Faculae: The Contrast at the Center of the Solar Disk Using Filigree Pictures,” Astron. Astrophys. 61, 397 (1977).

1976 (1)

1972 (2)

1969 (1)

R. B. Dunn, “Sacramento Peak’s New Solar Telescope,” Sky Telesc. 38, 368 (1969).

1964 (1)

Bahner, K.

K. Bahner, “Teleskope,” in Handbuch der Physik, S. Flugge, Ed. (Springer-Verlag, Berlin, 1967), Vol. 29, p. 245.

Brown, D. S.

D. S. Brown, “Optics for the 50 cm Vacuum Telescope,” in Technical Report of the Swedish Astrophysics Research Station on La Palma (1985).

Dunn, R. B.

R. B. Dunn, “High Resolution Solar Observations,” Space Res. 12, 1657 (1972).

R. B. Dunn, “Sacramento Peak’s New Solar Telescope,” Sky Telesc. 38, 368 (1969).

R. B. Dunn, “An Evacuated Tower Telescope,” Appl. Opt. 3, 1353 (1964).
[CrossRef]

R. B. Dunn, Sacramento Peak Observatory; private communication.

Fay, T.

Koutchmy, S.

S. Koutchmy, “Photospheric Faculae: The Contrast at the Center of the Solar Disk Using Filigree Pictures,” Astron. Astrophys. 61, 397 (1977).

Kühne, C.

C. Kühne, “The Concept of the New 60 cm Domeless Solar Telescope at Hida Observatory,” Osservazione e Memoire dell Osservatorio Astrofisico di Arcetri, Fasciolo, 106 (1978), p. 53.

Kusoffsky, U.

U. Kusoffsky, Swedish Astrophysics Research Station on La Palma; private communication.

Livingston, W. C.

Mehltretter, J. P.

J. P. Mehltretter, “On Thermal-Optical distortions of Glass Disks,” J. Opt. 10, 93 (1979).
[CrossRef]

J. P. Mehltretter, “Window for Vacuum Telescopes: Review of Problem Areas,” in Large European Solar Telescope: Report on a Study for the Joint Organization for Solar Observations (1981), Appendix D, p. 199.

J. P. Mehltretter, “The Fraunhofer Institute Vacuum Tower Telescope for Roque de los Muchachos,” Joint Organization for Solar Observations Annual Report (1975), p. 36.

Muller, R.

R. Muller, Observatoires du Pic du Midi; private communication.

Nakai, Y.

Y. Nakai, in Proceedings, Japan-France Seminar on Solar Physics, F. Moriyama, J. Henoux, Eds. (1981), p. 275.

Schröter, E. H.

E. H. Schröter, “Facilities of the Locarno Station of the Gottingen Observatory,” Joint Organization for Solar Observations Annual Report (1975), p. 28.

Sönnerlind, H.

H. Sönnerlind, Dept. of Strength of Materials and Solid Mechanics, Stockholm; private communication.

Wyller, A. A.

Appl. Opt. (3)

Astron. Astrophys. (1)

S. Koutchmy, “Photospheric Faculae: The Contrast at the Center of the Solar Disk Using Filigree Pictures,” Astron. Astrophys. 61, 397 (1977).

J. Opt. (1)

J. P. Mehltretter, “On Thermal-Optical distortions of Glass Disks,” J. Opt. 10, 93 (1979).
[CrossRef]

Sky Telesc. (1)

R. B. Dunn, “Sacramento Peak’s New Solar Telescope,” Sky Telesc. 38, 368 (1969).

Space Res. (1)

R. B. Dunn, “High Resolution Solar Observations,” Space Res. 12, 1657 (1972).

Other (11)

J. P. Mehltretter, “Window for Vacuum Telescopes: Review of Problem Areas,” in Large European Solar Telescope: Report on a Study for the Joint Organization for Solar Observations (1981), Appendix D, p. 199.

R. Muller, Observatoires du Pic du Midi; private communication.

R. B. Dunn, Sacramento Peak Observatory; private communication.

U. Kusoffsky, Swedish Astrophysics Research Station on La Palma; private communication.

D. S. Brown, “Optics for the 50 cm Vacuum Telescope,” in Technical Report of the Swedish Astrophysics Research Station on La Palma (1985).

H. Sönnerlind, Dept. of Strength of Materials and Solid Mechanics, Stockholm; private communication.

K. Bahner, “Teleskope,” in Handbuch der Physik, S. Flugge, Ed. (Springer-Verlag, Berlin, 1967), Vol. 29, p. 245.

J. P. Mehltretter, “The Fraunhofer Institute Vacuum Tower Telescope for Roque de los Muchachos,” Joint Organization for Solar Observations Annual Report (1975), p. 36.

E. H. Schröter, “Facilities of the Locarno Station of the Gottingen Observatory,” Joint Organization for Solar Observations Annual Report (1975), p. 28.

C. Kühne, “The Concept of the New 60 cm Domeless Solar Telescope at Hida Observatory,” Osservazione e Memoire dell Osservatorio Astrofisico di Arcetri, Fasciolo, 106 (1978), p. 53.

Y. Nakai, in Proceedings, Japan-France Seminar on Solar Physics, F. Moriyama, J. Henoux, Eds. (1981), p. 275.

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Figures (6)

Fig. 1
Fig. 1

Photograph of solar granulation and developing pores observed with the Swedish 25-cm solar telescope on La Palma. Note the excellent image quality that can be obtained even with a small telescope.

Fig. 2
Fig. 2

Drawing of the turret showing the lens and its cell, the two flat mirrors and one of the mirror supports, the rotating vacuum seals, and the separate guiding telescope.

Fig. 3
Fig. 3

Schematic drawing showing the optics in the turret, the tower, the third mirror, one of the exit windows, and the Littrow spectrograph.

Fig. 4
Fig. 4

Vertical displacement of the upper surface of the main objective due to the 570-mm Hg external air pressure at 2300-m altitude. Also shown for comparison are the corresponding displacements of two flat vacuum windows having thicknesses of 41.7 and 49 mm, corresponding to the edge and center thicknesses of the crown component, respectively. Also shown in the remaining error in the surface after a change in curvature has been applied, which compensates for most of the pressure distortion.

Fig. 5
Fig. 5

Expected performance as a function of wavelength for the main objective. The top curve shows the variation of back focal length (BFL) and the middle curve the maximum extension of a point source, as obtained from the ray trace calculations. The long focal length allows diffraction-limited performance from the ultraviolet to the infrared. The bottom curve shows the wavelength range, as obtained from the Rayleigh criterion, that can be observed without refocusing the objective.

Fig. 6
Fig. 6

Drawing of the lens cell. Note the O-ring which seals the vacuum and constitutes the support of the crown element of the objective, the adjustable cell of the flint component, and the annular diaphragm, the insulation, and the cooling coil which provides the temperature regulation the main objective.

Tables (1)

Tables Icon

Table I Data for the Main Objective

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