A configuration applicable to large astronomical telescopes has been developed specifically for lightweight monolithic mirrors in which the primary mirror is located on the same side of the declination axis as the secondary, placing the cassegrain focus very close to the declination axis. This configuration permits both a large instrument space and a single south polar tyne, resulting in a doubly asymmetric system. It is also shown that a passive closed-system air flotation support system can be used for both lateral and back support of the primary mirror, as contrasted to more complex active systems currently in widespread use.
A. B. Meinel, "A 1.8-m lightweight Doubly Asymmetric Equatorial Telescope Design," Appl. Opt. 10, 249-249 (1971)