Astronomical Instruments and Techniques
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031 Astronomical Optics 031.001
Optical analysis of thermally cycled 515 mm metallic
Al/Al-alloy mirrors.
L. Noethe, P. Giordano, K. Mischung, F. Franza, R. Wilson. Astron. Astrophys., Vol. 156, No. 1/2, p. 323-336 (1986). The figure stability of 16 spherical AI or Al-alloy mirrors of 515 mm diameter was tested in a thermal cycling experiment. The optical analysis was done by the Shack-Hartmann method. The general conclusion is that AI or Al-alloys are suitable for the fabrication of telescope mirrors, if, apart from the choice of the material and precautions during the fabrication, the blank is thermally stabilized before the final polishing.
031.002 A new type of field corrector. D.--{j. Su. Astron. Astrophys., Vol. 156, No. 1/2, p. 381-385 (1986). A new type of field corrector, which can correct both the aberrations and the atmospheric dispersion, is proposed. There are two cemented lenses in such a corrector. Each cemented lens is made of two different kinds of glasses, of which the indexes of refraction are near and the dispersions are different. The ce· mented surface is tilted. These two "lensms" are not only the components for correcting aberrations but also form spectra of objects in the field of view. When the two "lensms" are rotated relatively around the optical axis the dispersion will be changed. By means of this the atmospheric dispersion at different zenith distance can be compensated. A practical example is given and some other methods for correcting the atmospheric dispersion are also mentioned. 15 meter multiple mirror telescope design study. 1. R. P. Angel, N. 1. Woolf. Astrophys. J., Vol. 301, No.1, p. 478-501 (1986). Taking as a starting point the existing Multiple Mirror Tele· scope (MMT), a concept for a large and more advanced instrument has been developed. It makes use of four 7.5 m diameter paraboloidal glass primaries of the honeycomb-sandwich type being developed by the University of Arizona. These are mounted quite close together in a square configuration, with their axes coaligned. Two distinct optical configurations are provided. Wide fields of view in the optical and near-infrared are achieved at four separate fast Cassegrain foci (f/4.5). Secondaries of 3 m diameter are used with three-element refractive correctors de· signed by Epps to give flat 1' fields. When it is necessary to work at a combined focus an alternate set of small Cassegrain secondaries is used. The light is relayed to a coherent central focus, that is made available at several Nasmyth and other instrument sta· tions via steering mirrors. The mechanical and thermal design of the mirrors and the optical designs are aimed at an overall tele· scope image quality of 0':25. The use of advanced detectors and instruments now being designed to operate with this telescope is also outlined.
cussed. The objectives have focal length of about 1 meter. They are corrected for spherical aberration, secondary spectrum and coma. 031.005 Laser interferometers for testing astronomical optics. G. M. Popov, E. G. Popov. Izv. Krymsk
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