High-accuracy pointing and sub-second acquisition in a space optical communication terminal with ground-based verification method

This paper presents and implements a novel space optical communication terminal achieving high-precision open-loop pointing and sub-second acquisition. We further introduce a simple and accurate ground-based performance test method that enables end-to-end verification without the need for in-orbit experiments. To accurately measure open-loop pointing accuracy and acquisition characteristics, we formulate a comprehensive mathematical error model--covering structural misalignments, installation tolerances, and environmental effects--and estimate calibration parameters from stellar observations via a least-squares solution. Field experiments show a greater than 94% improvement in open-loop pointing accuracy, reducing the mean error from 2070.24 urad to 120.16 urad, and confirm an average acquisition time of 0.908 s with all trials completed in under 1 s. The method is generalizable to large-range, high-precision optical pointing measurements and astronomical observations.