Abstract

The maximum distance to which the secondary mirror can be moved with respect to its primary in a true Cassegrain telescope with limited image deterioration is found to be proportional to the fourth power of the focal ratio of the primary mirror. This limit is independent of all other parameters describing the system when the magnification of the secondary is greater than about 3.

© 1976 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. J. W. Foreman, Appl. Opt. 13, 2585 (1974).
    [CrossRef] [PubMed]
  2. W. B. Wetherell, M. P. Rimmer, Appl. Opt. 11, 2824 (1972).
    [CrossRef]

1974

1972

W. B. Wetherell, M. P. Rimmer, Appl. Opt. 11, 2824 (1972).
[CrossRef]

Foreman, J. W.

Rimmer, M. P.

W. B. Wetherell, M. P. Rimmer, Appl. Opt. 11, 2824 (1972).
[CrossRef]

Wetherell, W. B.

W. B. Wetherell, M. P. Rimmer, Appl. Opt. 11, 2824 (1972).
[CrossRef]

Appl. Opt.

J. W. Foreman, Appl. Opt. 13, 2585 (1974).
[CrossRef] [PubMed]

W. B. Wetherell, M. P. Rimmer, Appl. Opt. 11, 2824 (1972).
[CrossRef]

Cited By

OSA participates in CrossRef's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (5)

Fig. 1
Fig. 1

Design parameters used in the text for the Cassegrain telescope. The parameter ΔA is the distance the secondary mirror is moved from its designed position. Other parameters are described in the text.

Fig. 2
Fig. 2

The maximum size of the star image at the rms circle of least confusion as a function of the distance off-axis for three positions of the secondary mirror in a 20.3-cm f/3.325, f/15 Cassegrain telescope. The dotted line represents the Airy disk diameter.

Fig. 3
Fig. 3

Spot diagrams illustrating the star images produced at the rms circle of least confusion at ΔA = 0, −0.2, − 0.4 cm from top to bottom and distances off-axis of 0, 10, and 30 min of arc for a 20.3-cm, f/3.325, f/15 Cassegrain. The circle represents the size of the Airy disk, 1.14 sec of arc.

Fig. 4
Fig. 4

The size of the star image at the rms circle of least confusion as a function of the secondary position for a 20.3-cm f/3.325, f/15 Cassegrain telescope. The dotted line represents the Airy disk diameter.

Fig. 5
Fig. 5

The maximum tolerable distance that the secondary may be moved as a function of the primary focal ratio. This graph is independent of all other design parameters in a Cassegrain system.

Equations (9)

Equations on this page are rendered with MathJax. Learn more.

B = ( A F p - A 2 + 2 A F s - F s F p ) / ( F s - A ) .
M = b / A = ( F p + B - A ) / A .
Δ B = M 2 Δ A
x 0 = 1 n i = 1 n x i , y 0 = 1 n i = 1 n y i ,
R rms = { 1 n i = 1 n [ ( x i - x 0 ) 2 + ( y i - y 0 ) 2 ] } 1 / 2 .
( Δ A ) max 0.0058 f 4 · 0 cm ,
( Δ A ) max 126 λ f 4 · 0
W 40 = ( M + 1 ) [ 2 M ( M - 1 ) ( M f - B / 2 h 1 ) + 1 ] Δ A 256 λ M 3 f 4 ( M f - B / 2 h 1 ) .
Δ A = 128 λ f 4 W 40 [ 1 - 1 / M 2 + M + 1 2 M ( M f - B / 2 h 1 ) ]

Metrics