Resilient Free-Space Image Transmission with Helical Beams

$A\phantom{\rule{0}{0ex}}c\phantom{\rule{0}{0ex}}c\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}l\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}r\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}t\phantom{\rule{0}{0ex}}i\phantom{\rule{0}{0ex}}n\phantom{\rule{0}{0ex}}g$ $b\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}a\phantom{\rule{0}{0ex}}m\phantom{\rule{0}{0ex}}s$, which as they travel in free space bend themselves without the help of any optical device, are not only fascinating but can also be useful, as they can circumvent obstacles in their paths. So far applications have been limited to beams with convex trajectories (such as a parabola), but here the authors propose image transmission based on accelerating beams with nonconvex trajectories (a helix, for example). It is found that, because of the special mapping relationship between Fourier space and real space for nonconvex accelerating beams, images encoded in these beams are less affected by obstructions than images in convex beams ($e.g.$ Airy beams).