Axially symmetric hollow beams using refractive conical lenses

We explore the possibility of producing several beam shapes with conical
or cylindrical geometry using conical lenses. We discuss optical schemes
for generation of hollow laser beams; with 3D intensity distribution
surrounding all directions, a dark core region can be
obtained. these optical fields are important for the confinement
of cold atoms in 2D or 3D blue dipole trap.