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RE: Large wide-field telescope
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Title: Wide-field telescopes with a Mangin mirror
Authors: V.Yu. Terebizh

Two all-spherical catadioptric optical systems with a Mangin mirror are described. The design A (aperture 500 mm, f/2.0) has flat field of view of 7 deg in diameter; the design B (aperture 1000 mm, f/1.7) has 10-deg flat field. Both designs show near-diffraction-limited images. The D_80 diameter for the design A in the integral waveband 0.45-0.85 mcm varies from 1''.3 on the optical axis up to 2''.2 at the edge of the field (6.2-10.7 mcm); the corresponding range of the D_80 diameter for the design B is 1''.5-1''.9 (12.4-16.2 mcm). The designs include simple glass types, mainly Schott N-BK7 and fused silica. In case of need, better images could be attained by a choice of other glass, aspherisation of some surfaces, etc.

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Posts: 131433
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Title: A purely reflective large wide-field telescope
Authors: V.Yu. Terebizh

The design of a fast three-mirror telescope with flat field of view 3 degree in diameter is proposed. The telescope does not include auxiliary lenses. As an example, we consider an f/1.25 reflector with the 8.4-m entrance pupil diameter and 6.5-m effective aperture. The RMS diameter of a star image varies from 0''.13 on the optical axis up to 0''.19 at the edge of the field (6.7-9.8 mcm); the corresponding range of the D_80 diameter is 0''.18-0''.27 (9.3-13.5 mcm). All three mirrors are even aspheres of low orders (6th for the primary and tertiary mirrors, and 8th -- for the secondary mirror) with zero conic constant. Deviations of the optical surfaces from the nearest (in some sense) spheres are 1.73 mm, 0.07 mm, and 0.55 mm for the primary, secondary and tertiary mirrors, respectively. The length of the telescope is 7.34 m.

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