The folding model analysis of the elastic α+α scattering at the
incident energies below the reaction threshold of 34.7 MeV (in the lab system)
has been done using the well-tested density dependent versions of the M3Y
interaction and realistic choices for the 4He density. Because the
absorption is negligible at the energies below the reaction threshold, we were
able to probe the α+α optical potential at low energies quite
unambiguously and found that the α+α overlap density used to
construct the density dependence of the M3Y interaction is strongly distorted
by the Pauli blocking. This result gives possible explanation of a
long-standing inconsistency of the double-folding model in its study of the
elastic α+α and α-nucleus scattering at low energies using
the same realistic density dependent M3Y interaction