  In this work we describe dispersion force (van der Waals/Casimir)
measurements between gold surfaces at separations as close as 12 nm. The force
measurements were performed in the plane-sphere configuration by Atomic Force
Microscopy at distances ranging between 12 and 200 nm. This was accomplished by
using evaporated smooth metal surfaces for both sphere and plane, and stiff
cantilevers to minimize jump-to-contact problems. Finally, it is shown that
below separations of 100 nm experiment and theory are found in agreement within
10 % by including in the theory the measured optical properties of gold and
contribution from surface roughness.
