Singular beam scanning microscopy: preliminary experimental results

High-sensitivity and a high-speed nanoscale measurement is an important subject in modern industry, especially when analysis of high-speed moving nanoscale objects on a surface is required. Several objectives in this direction can be achieved by using singular beam microscopy, which we investigate experimentally for the examination of small phase steps. We discuss the challenges of rigorous modeling of experiments employing high-numerical-aperture illumination and describe experimental results performed with a medium numerical aperture of 0.55. The investigated equivalent phase step heights reached as low as 10 nm (about 1/15 rad).