Planar multi-aperture fish-eye lens using metagrating

The design of compact optical systems with large field of view has been difficult due to the requirement of many elements or a curved focal plane to reduce off-axis aberration. We propose a multi-aperture lens design to effectively resolve these issues. Metagrating-based deflectors are placed near entrance pupils of multi-aperture lens array to enhance field of view. A systematic design method is given in details. In design examples, a $\pm$80$^\circ$ field of view using only two planar optical elements is achieved. Also, the system is extremely compact with total track lengths an order of magnitude smaller than conventional fish-eye lenses, while the imaging performance is comparable with conventional designs.