Fig. 1. EDOF metasurface design and measurements. (A) The phase masks of an ordinary metalens and four different EDOF metasurfaces. (B) Scanning electron micrographs of the fabricated metasurfaces. Inset shows the pillar distribution. (C) We experimentally measured the intensity along the optical axis where panels from top to bottom represent illumination by 625 nm, 530 nm, and 455 nm wavelengths. A cross section on the y–z plane is taken for each of the 3D PSFs.

Fig. 2. Characterization of the metasurfaces. The PSFs of the singlet metasurfaces were measured under (A) 455 nm blue, (B) 530 nm green, and (C) 625 nm red. The corresponding x–y plane cross sections of the experimental MTFs are displayed with red lines from its PSF measured under red light, green lines under green light, and blue lines under blue light. (D) The x–y plane cross sections of the theoretical MTFs are displayed in row (E). The scale bar signifies 25 μm. The MTF plots have a spatial frequency normalized to 560 cycles/mm.

Fig. 3. Simulated imaging performance after deconvolution. Deconvolved images captured by the EDOF imaging system, using the simulated images and PSFs. The experimental counterpart can be found in Fig. 4.

Fig. 4. Imaging performance. Restored images taken from (A) an OLED display of colored letters in ROYGBVWG, (B) a colorful neighborhood, and (C) vibrant umbrellas against the sky. The scale bar signifies 20 μm. Note that the metalens images are raw and unrestored.

Fig. 5. Full color SSIM. The restored captures are scaled, rotated, and translated to align with the ground truth; then SSIM is calculated for each color channel for the metasurface.

Fig. 6. Phase (dashed lines) and amplitude (solid lines) response of the nanopillars, simulated using RCWA.

Fig. 7. Simulated captured images before deconvolution. The experimental counterpart is shown in Fig. 9.

Fig. 8. SSIM values when different regularization parameters are utilized.

Fig. 9. Raw images taken from an OLED display of colored letters in (A) ROYGBVWG, (B) a colorful neighborhood, and (C) vibrant umbrellas against the sky.

Table 1. Imaging Bandwidth, Defined as the Bandwidth at One Half of the Maximum PSF Similarity Coefficient

Table 2. Theoretical Bandwidths of EDOF Metasurfaces

Table 3. Exposure Durations for PSF (in Seconds)

Table 4. Exposure Durations for Imaging (in Seconds)

Table 5. SSIM on Simulation-Restored Images

Table 6. PSNR on Simulation-Restored Images (in dB)

Table 7. SSIM on Simulation-Restored Images (Gray-Scale Ground Truth)

Table 8. Diffraction Efficiencies of the Metasurfaces

Table 9. Peak Signal-to-Noise Ratio (PSNR) in dB