Applied Physics

A Liquid Mirror

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Science  26 May 2006:
Vol. 312, Issue 5777, pp. 1107
DOI: 10.1126/science.312.5777.1107c

Beyond the capacity to amuse carnival patrons, deformed mirrors can be highly useful in the field of adaptive optics. As light travels through the atmosphere, variations in temperature, density, and refractive index distort the optical wavefront. The cumulative effect of these distortions is a blurring of the image when, for example, the light is collected in the viewfinder of a telescope. If the extent of the wavefront distortion is measured, which can be done with the aid of an artificial guide star created using a laser beam, an adaptively deformable mirror can be tuned to iron out the distortions and restore the image clarity.

Vuelban et al. describe such a mirror, with a design based on electrocapillary actuation. A reflective membrane is placed atop a viscous dielectric liquid, which in turn floats above an aqueous electrolyte solution in a two-dimensional array of ∼350-μm-diameter microchannels. The liquid levels in each microchannel can be independently adjusted by application of a voltage, thereby inducing precise local deformations in the mirror surface above. An advantage of the liquid system is the large dynamic range of inducible deformation. The authors demonstrate a prototype device with an ∼2-ms response time. — ISO

Opt. Lett. 31, 1717 (2006).

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