  A focusing system such as a single lens or a spherical mirror imparts
intrinsic transverse orbital angular momentum (OAM) to spatiotemporal (ST)
coupled fields the ST intensity distribution of which presents ST covariance.
This fact may greatly simplify the experimental setups used to date to impart
transverse OAM. We evaluate analytically the imparted transverse OAM as a
function of the focal length and the covariance. The focused fields with
transverse OAM include elliptical ST vortices and rotating pulses without any
ST phase singularity such as the "lighthouse" pulse. We provide closed-form,
analytical expressions for these fields valid at any propagation distance from
the focusing system, which are of interest in applications such the interaction
of these fields with matter. In general, focusing of ST coupled fields with
intensity covariance generates mixed fields with ST vortices and rotating
pulse-fronts, where one or another feature dominates depending on the input
field.
