  We obtain the solution of the unitarity equation for the elastic processes in
terms of the expansion coefficients of the amplitude as a function on the
SO_mu(2.1) group. This approach is a generalization of the eikonal
representation to the case of small impact parameters and large transverse
momenta. We show how the unitarity relation is modified when the contributions
of the backward scattering are taken into account. We discuss the simplest
models of the profile functions in the following cases: full reflection, full
absorption and the combination of these two cases.
