Design and Simulation of Splicing of Sector-Shaped Segments of a Large Optical Telescope

In almost all large telescopes of segmented primary mirrors in the world hexagonal segments instead of sector-shaped segments are adopted. We compare the advantages and disadvantages of hexagonal segments and sector-shaped segments, and establish finite-element model of both types of segments with optimized 18 axial-support points. We further calculate the surface-deformation patterns of segments due to gravity when these segments are in three different directions, being laid horizontally, put vertically, and 45° from vertical. Our results show that sector-shaped segments can in principle have almost the same surface RMS as hexagonal segments if these two types of segments have the same area and number of axial-support points.However,sector-shaped segmented mirrors practically require much more complicated support and control systems.