  We theoretically study multiphoton ionization of the Ca atom irradiated by
the second (photon energy 3.1 eV) and third (photon energy 4.65 eV) harmonics
of Ti:sapphire laser pulses (photon energy 1.55 eV). Because of the dense
energy level structure the second and third harmonics of a Ti:sapphire laser
are nearly single-photon resonant with the ${4s4p}$ $^1P^o$ and ${4s5p}$
$^1P^o$ states, respectively. Although two-photon ionization takes place
through the near-resonant intermediate states with the same symmetry in both
cases, it turns out that there are significant differences between them. The
photoelectron energy spectra exhibit the absence/presence of substructures.
More interestingly, the photoelectron angular distributions clearly show that
the main contribution to the ionization processes by the third harmonic arises
from the far off-resonant ${4s4p}$ $^1P^o$ state rather than the near-resonant
${4s5p}$ $^1P^o$ state. These findings can be attributed to the fact that the
dipole moment for the ${4s^2}$ $^1S^e$ - ${4s5p}$ $^1P^o$ transition is much
smaller than that for the ${4s^2}$ $^1S^e$ - ${4s4p}$ $^1P^o$ transition.
