Image courtesy of H. B. Chan, University of Florida
(Upper left) A nanostructured silicon surface is used as one plate in a Casimir experiment. The structure dimensions are chosen to affect the electromagnetic modes that contribute most to the Casimir force at distances on the order of a few 100 nm. (Upper right) Schematic of the experiment, partially to scale. The gradient of the force is measured through a change in oscillation frequency of a micromechanical torsion oscillator fabricated from silicon (shown in bottom micrograph) as the distance between the upper sphere and the nanostructured surface is changed. The lower sphere serves as a simple mechanical spacer.