Integration and optical alignment of the Rubin Observatory Simonyi Survey Telescope with a laser tracker

Abstract

Precision in optical alignment is crucial for optimizing image quality in astronomical telescopes, particularly for wide-field survey telescopes such as the Vera C. Rubin Observatory, which will conduct the Legacy Survey of Space and Time (LSST). This paper explores the deployment and efficacy of laser tracker technology, specifically the Leica AT960/930, in maintaining optical alignment of the Simonyi Survey Telescope within tens of microns. Initially suggested by Burge et al. in 2007, 1 laser tracker technology has been instrumental in several major telescopes and is a cornerstone of operations at the Rubin Observatory, marking it as one of the first widefield telescopes to implement such advanced metrology. Here, we detail the process and outcomes of employing this technology in its integration, initial setup, and preliminary operations. In particular, we present detailed results on the structural flexure of the telescope at varying elevations, the effects of gravitational dynamics on the alignment of optical components, and the overall impact of azimuth and camera rotation on misalignments. Furthermore, our findings demonstrate that the operation of the laser tracker within the Active Optics System (AOS) allows realigning components within stringent tolerances in a single step, achieving near-perfect initial alignment. These capabilities demonstrate that we can achieve the necessary alignment for astronomical observations and establish a new benchmark for optical alignment in future large astronomical facilities.