| 摘要 |
A planetary astrographic telescope of the Cassegrain type having a concave paraboloidal primary mirror and a convex secondary mirror located in the spherical zone between the primary mirror and said primary mirror's focal point. The spherical secondary mirror receives the light reflected from the primary mirror. The secondary mirror, in turn, reflects such light through an aperture in the primary mirror to a focal plane located behind the primary mirror. The spherical secondary mirror and its holder are in combination sized to be not more than twenty percent of the diameter of the primary mirror and positioned in the spherical zone of light reflected from the paraboloidal primary mirror. One embodiment of the present invention is a tube containing the concave paraboloidal primary mirror and convex spherical secondary mirror with said tube attached to and supported on a mount at a height above a support surface.
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