We present a kind of large effective aperture metalens based on an optical sparse aperture (OSA) system. Each subaperture of the system is a metalens, which is comprised of just a thin Au film with patterned subwavelength rectangular annular arrays on a SiO2 substrate and has a numerical aperture of 0.46 with a diameter of 21.6 μm. Ring6 design was selected to enlarge the effective aperture and enhance the spatial resolution. Compared with the absent mid-frequency and high-frequency modulation transfer function of individual metalens, Ring6 can offer a full-frequency band and show a better restored image quality by using Tikhonov regularization.
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