Achromatic metalens array for full-colour light-field imaging

Abstract

A light-field camera captures both the intensity and the direction of incoming light1,2,3,4,5. This enables a user to refocus pictures and afterwards reconstruct information on the depth of field. Research on light-field imaging can be divided into two components: acquisition and rendering. Microlens arrays have been used for acquisition, but obtaining broadband achromatic images with no spherical aberration remains challenging. Here, we describe a metalens array made of gallium nitride (GaN) nanoantennas6 that can be used to capture light-field information and demonstrate a full-colour light-field camera devoid of chromatic aberration. The metalens array contains an array of 60 × 60 metalenses with diameters of 21.65 μm. The camera has a diffraction-limited resolution of 1.95 μm under white light illumination. The depth of every object in the scene can be reconstructed slice by slice from a series of rendered images with different depths of focus. Full-colour, achromatic light-field cameras could find applications in a variety of fields such as robotic vision, self-driving vehicles and virtual and augmented reality.

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Fig. 1: Light-field imaging with a metalens array.
Fig. 2: Characteristics of the radiance captured by the focused metalens array light-field-imaging system.
Fig. 3: Depth estimation of the scene combining Earth, a rocket and Saturn.
Fig. 4: Quantification of the imaging resolution of the light-field system with an achromatic metalens array.

Code availability

The code used for analyses and figures is available from the corresponding author upon reasonable request.

Data availability

The data that support the plots within this paper and other findings of this study are available from the corresponding authors upon reasonable request.

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Acknowledgements

The authors acknowledge financial support from the Ministry of Science and Technology, Taiwan (grant nos MOST-107-2112-M-001-042-MY3, MOST-107-2911-I-001-508, MOST-107-2911-I-001-510, MOST-107-2923-M-001-010-MY3) and Academia Sinica (grant nos AS-103-TP-A06, AS-TP-108-M12, AS-iMATE-108-41). The authors are also grateful for financial support from the National Key R&D Program of China (2017YFA0303700, 2016YFA0202103) and the National Natural Science Foundation of China (nos 11822406, 11834007, 11674167, 11621091, 11774164, 91850204). They are also grateful to the National Center for Theoretical Sciences, the NEMS Research Center of National Taiwan University, the National Center for High-Performance Computing, Taiwan, and the Research Center for Applied Sciences, Academia Sinica, Taiwan, for their support. T.L. is grateful for the support from Dengfeng Project B of Nanjing University.

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R.J.L., V.-C.S., S.W. and M.K.C. contributed equally to this work. R.J.L. and S.W. conceived the design, performed the numerical design, optical measurement and data analysis, and developed the algorithm. R.J.L., S.W., M.K.C. and C.H.C. co-wrote the manuscript. V.-C.S. and J.-W.C. performed the sample preparation. M.K.C., Y.-T.H., H.Y.K., T.L.C., Y.H.C. and C.H.C. built the optical system for measurement. J.C. and P.C.W. performed the numerical simulation and data analysis. J.-H.W. provided GaN film and performed the sample preparation. T.L., Z.W. and S.Z. organized the project, designed experiments, analysed the results and prepared the manuscript. D.P.T. organized the project, designed and developed the numerical design and optical measurement, analysed the results and prepared the manuscript. All authors discussed the results and commented on the manuscript.

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Correspondence to Shining Zhu or Din Ping Tsai.

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Supplementary information

Supplementary information

Supplementary Figs. 1–9, Supplementary Table 1

Supplementary video

A real-time depth map video of a scene

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Lin, R.J., Su, VC., Wang, S. et al. Achromatic metalens array for full-colour light-field imaging. Nat. Nanotechnol. 14, 227–231 (2019). https://doi.org/10.1038/s41565-018-0347-0

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