Aberration-Converged Annular Lithography uses micro-annular structures, making it particularly useful on curved substrates

https://www.eurekalert.org/news-releases/1106266

"overcomes difficult positioning/ low efficiency challenges using lithography on non-planar surfaces... using 2 axicons converts Gaussian beam into collimated annular beam which then passes through convex lens group, where aberration in 2nd convex lens reduces annular beam width in radial direction... 1.79 µm minimum average line width, >10X better... with extended depth of focus, defocus/ positional errors minimally impact exposure outcomes... can be integrated with other advanced manufacturing methods"