  We study experimentally and theoretically the equilibrium adhesive contact
between a smooth glass lens and a rough rubber surface textured with spherical
microasperities with controlled height and spatial distributions. Measurements
of the real contact area $A$ versus load $P$ are performed under compression by
imaging the light transmitted at the microcontacts. $A(P)$ is found to be
non-linear and to strongly depend on the standard deviation of the asperity
height distribution. Experimental results are discussed in the light of a
discrete version of Fuller and Tabor's (FT) original model (\textit{Proceedings
of the Royal Society A} \textbf{345} (1975) 327), which allows to take into
account the elastic coupling arising from both microasperities interactions and
curvature of the glass lens. Our experimental data on microcontact size
distributions are well captured by our discrete extended model. We show that
the elastic coupling arising from the lens curvature has a significant
contribution to the $A(P)$ relationship. Our discrete model also clearly shows
that the adhesion-induced effect on $A$ remains significant even for
vanishingly small pull-off forces. Last, at the local asperity length scale,
our measurements show that the pressure dependence of the microcontacts density
can be simply described by the original FT model.
