Non-uniformity correction of wide field of view imaging system

Requirements for wide field of view (FOV) imaging system reflect the need for both uniform illumination as well as excellent image quality across the entire FOV. As the monocentric lens combined with a parallel array of relay imagers achieves a wide-FOV while maintaining a high resolution, we studied the monocentric cascade imaging system (MCIS). However, the imaging experiment of the prototype shows two issues, including vignetting and non-uniform image quality over the full FOV. They affect the image stitching which is necessary for wide-FOV image acquisition. This paper studies how the position of the aperture stop affects the vignetting and the local aberrations in MCIS. Moving laws of the aperture stop and its relationship with the local aberrations are presented. Moreover, aspheric surfaces on proper surfaces are introduced and studied to balance the local aberrations. Accordingly, an MCIS with uniform illumination and good image quality is presented. The MCIS achieves a wide-FOV of 116.4 degrees and an instantaneous FOV of 0.0021 degrees. It keeps a relative illumination exceeding 97% during the full FOV. The modulation transfer function (MTF) is over 0.285 at the Nyquist frequency of 270 lp/mm. This paper provides a profound theorical reference for further applications and developments of MCIS. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

This paper investigates the impact of aperture stop position on vignetting and local aberrations in monocentric cascade imaging system (MCIS). By introducing aspheric surfaces on proper surfaces, an MCIS with uniform illumination and good image quality is achieved.