Generation of a boat-shaped beam due to a tightly focused comatically aberrated azimuthally polarized beam

In this paper we investigate the focal volume properties due to a tightly focused azimuthally polarized beam in the presence of coma. We use vectorial diffraction theory to obtain the Cartesian components of the electric field near the focus, which are then used to compute the resulting energy densities. We have observed that in the presence of a moderate amount of coma in an azimuthally polarized beam, the resultant field near the focus gives rise to a boat-shaped intensity distribution comprising a relatively dark focus surrounded from five directions. Generation of such a dark volume surrounded by intense light in all but one direction appears interesting since the focal volume is quite distinct in comparison with other reported works where normally the dark volumes are surrounded by intense light from all directions. In this work we also investigate the time evolution of the resultant electric field vector in the entire focal volume by drawing the polarization ellipse at each location.