Fig. 1. Compound eye structure^[1]. (a) Biological compound eye structure; (b) bionic compound eye structure

Fig. 2. Principle and functions of light field camera^[23]. (a) Schematic diagram of the light field camera structure; (b) four-dimensional light field information collected by the light field camera; (c) macropixels of the four-dimensional light field; (d) sub-aperture images from different viewing angles; (e) schematic diagram of the digital refocusing principle; (f) refocusing results of the four-dimensional light field

Fig. 3. Motion detection by optical flow method^[24]. (a) Schematic diagram of the insect visual center structure; (b) process of the optical flow method motion detection; (c) from left to right are the original image, preprocessed image, optical flow field image, and extracted moving target

Fig. 4. Principle of metasurface light field modulation. (a) Generalized Snell's law^[4]; (b) “V”-shaped resonance type metasurface^[4]; (c) propagation phase type metasurface^[33]; (d) geometric phase type metasurface^[35]

Fig. 5. Achromatic metalens and light field camera. (a) Reflective achromatic metalens in the infrared band^[41]; (b) transmissive achromatic metalens in the visible band^[42]; (c) light field camera based on achromatic metalens array^[43]

Fig. 6. Metalens array based devices. (a) Metalens array with lateral chromatic aberration effect and its imaging of colored object light^[44]; (b) material discrimination and depth information restoration by SLIM^[44]; (c) polarization multiplexing metalens array with different focusing for left- and right-hand circular polarization light^[45]; (d) PSFs with different depth of field under two polarizations, the depth of field can cover the range from 3 cm to infinity^[46]; (e) from left to right are the four-dimensional light field information collected, the high-quality light field image processed by the neural network, and the final extreme depth of field image^[46]; (f) high-dimensional and multi-photon quantum light sources based on metalens array^[47]

Fig. 7. Wide-angle imaging by refractive optical elements and meta-optical elements. (a) Oblique incident light produces coma aberration; (b) commercial fisheye lens realizes wide-angle object light reception; (c) double-layer wide-angle imaging metasurface^[49]; (d) multi-layer metasurface structure by topology optimization^[50]; (e) single-layer quadratic phase metalenses can focus beams meet paraxial conditions^[52]; (f) quadratic metalenses integrated with apertures, they have less background noise. Left is the air-gap structure and right is the medium-gap structure^[54]

Fig. 8. Metalens array wide-angle camera^[55]. (a) Schematic diagram of wide-angle imaging based on planar metalens array; (b) wide-angle imaging on the detector when the projection functions are P(α)=0, P(α)=-f tan α, P(α)=-fα, respectively; (c) shape of the incident light spot at different angles when the design angles are α=0° and 30°, respectively; (d) viewing angle range covered by each lens in the array

Fig. 9. Performance tests of metalens array wide-angle camera^[55]. (a) Positions of the projected image and the detection results, the design angle of the clearest imaging is consistent with the detection results; (b) MTF comparison of a single metalens and a metalens array for incident light at different angles; (c) from top to bottom are the wide-angle imaging scene, sub-image stitching and final wide-angle imaging result comparison, the viewing angle of the wide-angle metalens array is three times that of the traditional metalens

Fig. 10. Polarization multiplexing metalens array^[56]. (a) From left to right are the schematic diagram of the lens multiplexing method, optical microscopic pictures, and the sample; (b) meta-lens integrated imaging device; (c) images by the metalens array under two different polarizations; (d) (e) synthesized large-field high-resolution microscopic image and its details

Fig. 11. Chip-scale metalens array integrated microscope^[57]. (a) Schematic diagram and structure of the device; (b) 1×, 2×, and 3× magnified imaging effects of the device without and with a circularly polarizing film; (c) schematic diagram of the design principle, for circularly polarized incident light, each metalens will obtain two independent phase modulations; (d) (e) optical microscopy image of the 16×16 metalens array and its real image; (f) images collected by the device under two polarizations; (g) final stitching result, the field of view reaches 4 mm×4 mm, and the resolution reaches 1.74 μm

Fig. 12. Performance test of metalens array integrated microscope^[57]. (a) Characterization results of the USAF1951 resolution plates with wavelengths from 450 nm to 510 nm; (b) imaging results of mosquito larvae at different depths; (c) highly integrated microscope device prototype; (d) wide-field imaging of biological cells, the result (left), a detailed magnification (upper right), and a comparison of the same area captured with a 10× Olympus microscope objective (lower right); (e) comparison of traditional microscope imaging results (first row) and imaging chip imaging results (second row)