  The long standing problem on finding the height correlation function is
studied by the inverse scattering problem. We propose a new method in the frame
work of Kirchhoff theory which we call "path derivation of scattered wave
(PDSW)" in order to obtain an expression for direct measurements of the height
correlation function. This would provide adequate insight to rough surfaces.
The efficiency of this method is due to the fact that the height correlation
function could be estimated directly by measurements of the scattered intensity
on a suggested path. The model is tested numerically and an experimental setup
is suggested.
