Fig. 5: Experimental results.
From: Large area optimization of meta-lens via data-free machine learning
a–c Scanning Electron Microscope (SEM) images of the fabricated SiN meta-lens with focal length F = 500μm. The scale bars correspond to 1 μm, 0.1 μm, and 1 μm, respectively. d Counts of pillar half-widths of the forward and inverse designed lens. e Measured intensity contained in the region given by 3 × FWHM of the focal spot vs lens numerical aperture. The units are normalized to the largest intensity integral of the forward design. Error bars are standard deviations of energy computed at 1216 data points (dimension of the sensor). f Maximum intensity at the focal spot. The inverse designed lenses outperform the forward designed lenses for NA> 0.44. The lines are visual aids and not fits to a theoretical model. Units are normalized to the largest intensity of the forward designed lens. In the NA = 0.9 (F = 250μm) case an improvement of 53% is observed. The error bars are standard deviations of intensity at the focal plane. g Experimentally measured field intensities of the forward designed lens and h of the inverse designed lens. i Intensity slice at the focal spot. The intensities are normalized such that the maximum intensity of the forward designed lens is 1. The intensity of the inverse designed lens focal spot is 1.25.
