Vortex inverted pin beams: mitigation of scintillations in strong atmospheric turbulence.

We recently introduced a new class of optical beams with a Bessel-like transverse profile and increasing beam width during propagation, akin to an "inverted pin." Owing to their specially engineered distribution, these beams have shown remarkable performance in atmospheric turbulence. Specifically, inverted pin beams (PBs) were found to have a reduced scintillation index as compared to collimated or focused Gaussian beams as well as other types of pin beams especially in moderate to strong turbulence.

Inverted pin beams for robust long-range propagation through atmospheric turbulence.

We introduce a new, to the best of our knowledge, class of optical beams, which feature a spatial profile akin to an "inverted pin." In particular, we asymptotically find that close to the axis, the transverse amplitude profile of such beams takes the form of a Bessel function with a width that gradually increases during propagation. We examine numerically the behavior of such inverted pin beams in turbulent environments as measured via the scintillation index and show that they outperform Gaussian beams (collimated and focused) as well as Bessel beams and regular pin beams, which are all optimized, especially in the moderate and strong fluctuation regimes.

Altering the Surface Properties of Metal Alloys Utilizing Facile and Ecological Methods.

The development of a superhydrophobic and, even, water-repellent metal alloy surface is reported utilizing a simple, fast, and economical way that requires minimum demands on the necessary equipment and/or methods used. The procedure involves an initial irradiation of the metallic specimen using a femtosecond laser, which results in a randomly roughened surface, that is subsequently followed by placing the item in an environment under moderate vacuum (pressure 10 mbar) and/or under low-temperature heating (at temperatures below 120 °C). The effects of both temperature and low pressure on the surface properties (water contact angle and contact angle hysteresis) are investigated and surfaces with similar superhydrophobicity are obtained in both cases; however, a significant difference concerning their water-repellent ability is obtained.