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Ultrathin cameras using annular folded optics

A special kind of ultrathin lenses using annular folded optics is introduced, which has potential for compact imagers. Their long focal lengths can be contained within a limited track. Light enters the lens through an outer annular aperture and is focused by a series of concentric zone reflectors to the image plane. It is an approach to implement high sample resolution imaging, large aperture and ultrathin characteristic at the same time. This optic has the advantages of both the compactness of miniature cameras and the high imaging quality of large cameras. In this paper, the principle, structure, and design method of this type of ultrathin lens is introduced. An optimized design and its performance evaluation are reported. Such lens can be applied to the situation where the bulk and mass are so limited that conventional imaging systems are unsuitable.