@article {BaranekOE15, title = {Aberration resistant axial localization using a self-imaging of vortices}, journal = {Opt. Express}, volume = {23}, year = {2015}, pages = {15316{\textendash}15331}, keywords = {MF}, doi = {10.1364/OE.23.015316}, author = {Michal Bar{\'a}nek and Petr Bouchal and M {\v S}iler and Zden{\v e}k Bouchal} }