Advancing the Vera C. Rubin Observatory Active Optics Control System

The Vera C. Rubin Observatory is poised to achieve its highly anticipated first light in early 2025, marking the start of an era of transformative observational capabilities. As the observatory nears its first light, the commissioning of the Active Optics System (AOS) becomes increasingly critical. Comprising an open-loop and a closed-loop component, the AOS delivers real-time corrections for the alignment and mirror surface perturbations, ensuring seeing-limited image quality across the 3.5-degree field of view. In this paper, we present a thorough examination of recent advancements in the AOS at the Rubin Observatory. We begin by detailing the enhancements in the open-loop system, focusing on the improvement of Look-Up Tables (LUTs). Next, we discuss the closed-loop control improvements, particularly our novel approach using double Zernike polynomials and improvements made to eliminate degeneracies. Overall, these initial verifications and improvements not only mark significant progress towards full-system verification, but also refine the capabilities of the AOS, which is key for maintaining long-term operational efficiency and achieving the required image quality.