Application of fisheye lenses in sky polarization measurement and its compensation method

Fisheye lenses, with their ability to capture a wide field of view, offer significant potential for sky polarization measurements. However, the complex polarization transformations induced by fisheye lenses make conventional polarization measurement techniques unsuitable for direct application. This paper presents a compensation method based on Stokes parameters and Mueller matrices to address this challenge. By constructing a device capable of introducing known polarized light from various directions, the Mueller matrix distribution of the fisheye lens is measured. Pixel-level inverse computation is then employed to achieve polarization compensation. A high-resolution partial Mueller matrix model (3×3 matrix per pixel) was established to account for the unique thickness variations and refractive angle differences across the fisheye lens, enabling precise polarization correction. The proposed method lays a foundation for accurate sky polarization measurement by effectively eliminating the fisheye lens’s influence on polarization signals.