  A theoretical study of ionization of the hydrogen atom due to an XUV pulse in
the presence of an IR laser is presented. Well-established theories are usually
used to describe the problem of laser assisted photoelectron effect. However,
the well-known soft-photon approximation firstly posed by Maquet et al in
Journal of Modern Optics 54, 1847 (2007) and Kazansky's theory in Phys. Rev. A
82, 033420 (2010) completely fails to predict the electron emission
prependicularly to the polarization direction. Making use of a simple
semiclassical model, we study the angle-resolved energy distribution of
photoelectrons for the case that both fields are linearly polarized in the same
direction. We thoroughly analize and characterize two different emission
regions in the angle-energy domain: (i) the parallel-like region with
contribution of two classical trajectories per optical cycle and (ii) the
perpendicular-like region with contribution of four classical trajectories per
optical cycle. We show that our semiclassical model is able to asses the
interference patterns of the angle-resolved photoelectron spectrum in the two
different mentioned regions. Electron trajectories stemming from different
optical laser cycles give rise to angle-independent intercycle interference
known as sidebands. These sidebands are modulated by an angle-dependent
coarse-grained structure coming from the intracycle interference of the
electron trajectories born during the same optical cycle. We show the accuracy
of our semiclassical model as a function of the time delay between the IR and
the XUV pulses and also as a function of the laser intensity by comparing the
semiclassical predictions of the angle-resolved photoelectron spectrum with the
continuum-distorted wave strong field approximation and the ab initio solution
of the time dependent Schr\"{o}dinger equation.
