  We employ the Kramers-Henneberger Hamiltonian for time-independent
calculations of multi-photon ionization of atoms with one and two electrons. As
compared to the electromagnetic interaction in the length and velocity gauges,
the presently employed Kramers-Henneberger gauge has an advantage of the dipole
matrix elements for the free-free electron transitions being finite and
well-defined quantities. This circumstance simplifies considerably the
computations and allows to obtain accurate results for the two-photon
ionization of realistic atomic systems.
