Transversal optical singularity induced precision measurement of step-nanostructures

Optical singularities indicate zero-intensity points in space where parameters, such as phase, polarization, are undetermined. Vortex beams such as the Laguerre–Gaussian modes are characterized by a phase factor e^il^θ, and contain a phase singularity in the middle of its beam. In the case of a transversal optical...