Generation of closely located light spots using specular Airy laser beams

We conduct a comparative numerical study of the formation of closely located light spots in the focal plane of diffraction gratings and binary optical elements matched with Hermite-Gaussian modes and specular Airy beams. It is shown that while gratings allow a set of uniform focal spots to be generated with high accuracy, the resulting pattern quickly deteriorates when displaced from the focal plane. Due to their modal properties, Hermite-Gaussian beams are low-sensitive to defocusing, but produce focal spots different in size and intensity. Specular Airy beams offer a trade-off solution - they produce a more uniform intensity pattern of light spots than the Hermite-Gaussian modes, at the same time showing a lower sensitivity to defocusing. Experiments with a tunable laser have confirmed the above-mentioned advantages of the specular Airy beams in comparison with the Hermite-Gaussian modes, also showing good spectral stability of the manufactured diffraction optics.