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The star sensor is the most accurate measurement instrument in the spacecraft attitude measurement system, and the accurate centroid of the star point is the basis for ensuring the performance of the star sensor. Currently, the centroid of the gray method is the most widely used centroid extraction method in practice. Systematic errors caused by the centroid of the gray method and random noise in the detector imaging process are the main factors contributing to the deviation of the star centroiding coordinates. Considering the relationship between the point spread function and the pixel gray value, this paper proposes a centroiding method to reduce the star point centroiding error by fusing a priori information and energy distribution. The star charts are first preprocessed using a curvature filter and Gaussian blur to reduce the random noise. Then the complexity of the point spread function is considered, and the pixel gray values are corrected based on a priori information and gray value fuzzy processing. Finally, the symmetry of the one-dimensional energy distribution is used to quickly determine the sub-pixel deviation to get the star centroid coordinates. Through simulation and physical simulation experiments, the method was verified to be effective, and the extraction accuracy met the requirements of high-precision star sensors. The night sky observation test results demonstrate that the method in this paper can improve the measurement accuracy of the star sensors. [ABSTRACT FROM AUTHOR]

The heterostructure integration of nanostructures, which can involve higher freedom of degree by applying two or more materials into one integrated photonic or electromagnetic devices, attracted extensively increasing attention among the communities of electrons, photonics, materials science, and engineering. However, it is still a challenging topic to realize heterostructure integration with accurate micro–nano-scale geometry in a large area. Here, we propose the secondary-deposited elevated self-assembling nanosphere lithography for large-area heterostructure integration of plasmonic metasurface. As the proof of concept, an infrared metasurface composed of Au–Ag crescent pairs is realized in the practice. By adjusting the evaporation angle, crescent pairs with different morphologies can be freely machined without changing masks. Optical characterization and numerical results show that the heterostructure crescent-pair metasurface owns uniform and stable geometrical properties and flexible capability on infrared optical field modulation. Our work enriches the degree of freedom of nano-structure-based optical devices and paves the heterostructure integrated metasurface to potential industrial applications with large dimension, low cost, and fast production. [ABSTRACT FROM AUTHOR]