Fabrication of a Large Thin Hexagonal Mirror Segment With a Spherical Surface of Precisely Defined Radius of Curvature

Abstract

The status of the fabrication of a large thin hexagonal mirror is described. The mirror will be used in a prototype of the segmented mirror control system for the proposed University of California Ten Meter Telescope. The telescope design calls for a semented primary mirror with thirty-six 1.8-meter diameter hexagonal segments. Each segment will be made to a precisely defined surface with a precisely defined radius of curvature (35m) such that the rms deviation from the ideal surface is less than 30 nanometers.