The Large Fiber Array Spectroscopic Telescope: opto-mechanical design and architecture

Abstract

This paper describes the preliminary mechanical design and optomechanics of LFAST, the Large Fiber Array Spectroscopic Telescope. The 1,200 m2 array comprises 132, open air, alt-az tracking mounts, each carrying 20 small coaligned telescopes in a 5 m square U-shaped space frame about a central, dual-axis worm drive. Each unit telescope has a 0.76 m, f/3.5 mirror, a prime focus assembly with field corrector and a guide camera, and feeds a 17um, 1.3 arcsecond optical fiber. LFAST was designed specifically as a fiber fed spectroscopic telescope. By being built from thousands of mass-produced components it will be much cheaper per square meter of collecting area than phased monolithic telescopes currently under construction, like GMT and ELT. Cost effective dome-less operation is made possible by the structural design that maximizes stiffness and active compensation for wind induced jitter. The primary mirrors are protected when not in use by sub-horizon pointing of tracking mount and mirror covers. © 2022 SPIE.