Precision enhancement method for multiplexing image detector-based sun sensor with varying and coded apertures.

The multiplexing image detector-based sun sensor has an extremely high accuracy and a large field of view (FOV) due to its large focal length, hundreds of apertures, and tens of sub-FOVs. Because of the optical interference effect, the diffraction spots of the sun on the image detector will be greatly influenced by the incident sun angles and the sizes of apertures, which affect the extraction precision of the sun spot centroid to a great extent. In this work, according to the Huygens-Fresnel diffraction integral formula and the aperture numerical simulations at different incident sun angles, we present a novel proposal for the mask with varying aperture sizes in different sub-FOVs. We encoded the aperture arrays with distance information for sub-FOV distinction. The laboratory test results indicated that, compared with the same aperture pattern design, the extraction precision of the sun spots with the varying apertures pattern design was better in a larger angle and more stable in the whole FOV, and the precision of the sun sensor could be improved to 1.32" (1σ) from 4.52" (1σ) at a 50° incident sun angle.