Fig. 2: Focal profiles of diffractive and hybrid lenses at visible wavelengths.

a, b X-Z confocal scans of a lower NA diffractive lens (a) and a higher NA diffractive lens (b) focusing 633, 612, 542, and 488 nm light. These lenses experience strong negative dispersion. c, d X-Z confocal scans of a GRIN hybrid lens (c) and a geometric hybrid lens (d) focusing 633, 612, 542, and 488 nm light. These lenses experience reduced negative dispersion. For all lenses, the horizontal white dotted lines are the approximate reference focal planes for 633 nm light. The horizontal white solid lines represent the approximate interface between the PSiO₂ host medium and air. The lens cartoons represent the approximate locations of the printed lenses. All scans are 90 μm in X and are to scale with each other in Z.