<title>Configurations for an extremely large telescope with a spherical or aspherical primary mirror</title>

Abstract

In this paper four 30 m to 100 m telescope configurations are put forward. (1) A transit mounting telescope with spherical primary mirror which can be rotated continuously only around the level axis, and a corrector on the prime focus is used to track the objects during they passing through the meridian cycle about 1.5 hours. (2) The mounting is the same as the first one, but to get higher image quality and smaller corrector, we applied the idea, which Su et al put forward in 1986, to actively change the shape of the area in use on the primary mirror during tracking in this telescope. (3) The third one is a fully fixed mounting telescope, but it is composed of several telescopes like the first or the second configuration in parallel along south and north direction. (4) An alt-az mounting telescope with a f/0.6 aspherical primary mirror. There are three important ideas in this paper: (a) transit mounting; (b) primary mirror with continuous variable shape during observation; (c) very fast f ratio telescope with fixed shape aspherical primary mirror. All these configurations can be used in optical, infrared, sub-millimeter and radio telescopes and also can be used on the moon.