Intensity distribution in the focal region of a “doughnot” mode

Abstract

We study the intensity distribution of a TEM01+10 mode propagating through a single diffraction limited lens. The theoretical intensity distributions along the optical path remain similar until the truncation effects, due to the lens diameter, are negligible. The focal distribution is however very sensitive to truncation, and this is relevant for industrial applications of high power lasers. An experimental system to measure the intensity distribution at the focal plane is described and its results are compared with the theory.