ABSTRACT
Although mechanical mounts for large, horizontal-and vertical-axis mirrors are important for fixed installations, such as in test equipment associated with mirror fabrication, the variable-orientation case presents many more mount design challenges. Optical instruments for astronomical, military, aerospace, and industrial applications that involve large mirrors generally require those mirrors to be moved about with respect to the Earth’s gravitational field. Much of what was said in Chapters 3 and 4 regarding various radial and axial supports in the contexts of horizontal-and vertical-axis mirror applications also applies to the variable-orientation mirror. Means for controlling the distribution of forces acting on the mirror to minimize optical surface deflection as a function of the changing direction of gravity are described in this chapter. Mirror position-defining systems that ensure the retention of mirror-to-telescope alignment also are described. The chapter closes with a discussion of techniques for handling large mirrors during fabrication, transport, installation, and maintenance (as required for recoating).
