Research on the design method of an optical system for star sensors with low centroid drift under under-corrected aberrations

Addressing the scientific challenge that the physical constraints of optical system volume place on the measurement accuracy of star sensors, this paper proposes an optimized design method based on intentional under-correction of optical aberrations. We establish a mathematical model and conduct simulations to analyze the relationship between star centroid drift and primary aberrations. The results show that spherical aberration, astigmatism, field curvature, and axial chromatic aberration have minor effects, whereas coma, distortion, and lateral chromatic aberration have greater influence. Guided by this sensitivity profile, we designed a centroid-optimized optical system using intentional aberration under-correction. Compared with a traditional image-quality-based design, the proposed system reduces star centroid drift by about 3-fold, to 5.2 μm, for fields of view of 10° and above, despite larger spherical aberration and field curvature. Prototype tests confirm the designed aberration distribution, with a maximum measured centroid drift of 6.5 μm, in good agreement with predictions.