Applied Physics

Visualizing the Casimir Force

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Science  27 Oct 2006:
Vol. 314, Issue 5799, pp. 566
DOI: 10.1126/science.314.5799.566b

When two perfectly conducting plates are brought close together, fluctuations in the vacuum field give rise to a difference in electromagnetic modes within the gap (which are limited to integral wavelength multiples equal to the gap width) and those outside the plates (which span an essentially infinite range). The resulting pressure difference thereby forces the two plates together. This quantum mechanical effect, termed the Casimir force, is of fundamental interest in its own right, but it is also becoming an important concern in micro- and nanoelectromechanical devices as a limiting factor in their operation.

Experiments to gauge this effect have generally been limited to fairly simple geometries and materials. Petrov et al. present an optical technique based on dynamic holographic interferometry. Deformation of a reflective pellicle due to Casimir force variations, induced by the back-and-forth motion of an opposing aluminum-coated lens, is detected as a shift in the phase and diffraction pattern of an output hologram. The setup relies on two-wave mixing of interfering light beams in a photorefractive cobalt-doped barium titanate crystal. Because this technique is sensitive and quite general, it should be useful for studying realistic device considerations, as well as exploring the effects of dielectric properties and conductivity. — ISO

Opt. Lett. 31, 3167 (2006).

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