  In the present work, the effect of AC-Stark shift (i.e. light-shift) in
optical dipole trap on in-situ absorption probe imaging of the trapped atoms
has been investigated. We have calculated the light-shift of various energy
levels of $^{87}$Rb atoms relevant for trapping in an optical dipole trap
(ODT). The spatial varying intensity of the ODT beam results in position
dependent light-shift (i.e. AC-Stark shift). Such modifications in the energy
levels of the atom result in modification in the absorption cross-section,
which finally modifies the optical density (OD) in in-situ absorption imaging
at a given wavelength of imaging probe beam. Incorporating the light-shift in
analysis of images, the correct number of atoms in the optical dipole trap has
been estimated for the experimentally observed absorption images of the trapped
cloud. The in-situ imaging and this work can be useful in estimating the
instantaneous loss rate from the trap during the evaporative cooling of trapped
atom cloud.
