  In this work quantum metrology techniques are applied to the imaging of
objects with a non-uniform refractive spatial profile. A sensible improvement
on the classical accuracy is shown to be found when the "Twin Beam State" (TWB)
is used. In particular exploiting the multimode spatial correlation, naturally
produced in the Parametric Down Conversion (PDC) process, allows a 2D
reconstruction of complex spatial profiles, thus enabling an enhanced imaging.
The idea is to use one of the spatially multimode beam to probe the sample and
the other as a reference to reduce the noise. A similar model can be also used
to describe wave front distortion measurements. The model is meant to be
followed by a first experimental demonstration of such enhanced measurement
scheme.
