Since mobile phones, smartphones and tablets
are extremely compact and space-saving, conventional lens systems with their mechanical focusing devices cannot be used in these devices. Liquid lenses, in which the shape of a drop of liquid is changed, have been developed for these applications. Liquid lenses use mechanical forces or the electrowetting effect
with which thesurface shape of liquids can be changed. In mechanical liquid lenses, the polymer liquid is sandwiched between a solid substrate and a flexible membrane. To change the focal length
, additional fluid is forced into the lens from a reservoir, causing the membrane to deform spherically.
With such mechanically working liquid lenses, focal lengths between 20 mm and 1,000 mm can be set.