posted on 2023-10-06, 15:03authored byZhanyi Zhang, Lingyun Xie, Jian Zhang, Tao He, Jingyuan Zhu, Zhanshan Wang, Xiong Dun, Xinbin Cheng
With
the continuous advancement of technology, there is a growing
demand for depth-detection cameras with a small footprint and high
photon throughput. Metalenses offer an excellent platform for implementing
single-lens depth-detection cameras. However, the narrow operational
bandwidth of the metalenses used in these miniaturized cameras significantly
limits the photon throughput. Here, we propose a broadband dispersionless
double-helix metalens (DL-DH metalens) to enhance the photon throughput
and mitigate motion blur in miniaturized passive depth-detection cameras.
Through engineering the dispersion, the DL-DH metalens was designed
to achieve an irrotational double-helix point spread function (DH-PSF)
over the broadband wavelength, thus eliminating the depth-detection
error caused by chromatic aberration. The operational bandwidth of
the fabricated metalens was expanded to 200 nm for obtaining higher-photon
throughput, resulting in a 10-fold reduction in the exposure time
compared with that observed for a narrow operational bandwidth of
30 nm. The sharp images could be captured by the DL-DH metalens to
acquire accurate depth information, even in the presence of moving
objects. Our proposed metalens provides a solution for enhancing the
photon throughput in miniaturized passive depth-detection cameras
operated in low-light environments.