Tiny Observatory for Telescope Optimization (TOTO): testing algorithms for autonomous on-orbit alignment for space-based telescope systems

The Tiny Observatory for Telescope Optimization (TOTO) is an optical testbed designed to evaluate the efficacy of autonomously driven alignment algorithms for space-based telescope systems. For space-based missions, active control of the telescope on-orbit offers potential to relax passive alignment requirements and reduce on-ground verification activity. TOTO is used to evaluate and verify simulation work of two primary alignment algorithms, Stochastic Parallel Gradient Descent (SPGD) and focus-diverse phase retrieval. Previous simulation work has confirmed that by using SPGD for coarse alignment followed by focus-diverse phase retrieval for fine alignment, we can reach diffraction-limited performance on-orbit. This paper presents the results of the autonomous alignment algorithm of a TMA using TOTO. We report the current status of TOTO as well as preliminary results from SPGD and phase retrieval on the testbed using monochromatic light source to simulate a natural guide star.