Optical-Algorithm Co-Design of a Lightweight Petzval Star Tracker with Selective Asymmetric Aberration Suppression

Traditional high-precision star trackers rely on long-focal-length optical configurations, which suffer from bulky volume and heavy weight, which restricts their application to small satellite platforms. Meanwhile, lightweight optical architectures inevitably introduce residual optical aberrations that distort star spot energy distribution and degrade centroid extraction accuracy. Targeting Petzval-type star trackers, this paper proposes an optical-algorithm collaborative lightweight design scheme. First, a coupling mathematical model between centroid positioning error and four asymmetric optical aberrations is established to quantify the error contribution hierarchy of coma, astigmatism, distortion, and lateral chromatic aberration. Second, an aberration dimensionality-reduction optimization method is proposed to selectively constrain precision-sensitive asymmetric aberrations; the conventional six-element Petzval lens group is simplified to a four-element lightweight configuration, reducing lens count by 30% and total system length from 27 mm to 21 mm. Finally, a three-stage joint compensation framework consisting of aberration residual identification, iterative centroid offset correction, and regularized Richardson–Lucy image restoration is constructed for on-orbit low-computation platforms. Ground star-map tests and on-orbit measurements demonstrate that the star centroid error is reduced from 0.098 pixels to 0.014 pixels after compensation, corresponding to an 85.7% improvement in localization precision. The 16 μm in-spot energy concentration rises from 76.2% to 86.5%, with full-field energy uniformity improved by 19.2%. Attitude measurement accuracy better than 3″ (3σ) is achieved for the X- and Y-axes (roll/pitch). The system exhibits favorable robustness under stray-light and multi-scene observation conditions. This integrated optical-algorithm solution realizes arcsecond-level attitude measurement for roll and pitch axes under strict lightweight constraints.