Generalized refractive tunable-focus lens and its imaging characteristics.

Conventional lenses made from optical glass or plastics have fixed properties (e.g. focal length) that depend on the index of refraction and geometrical parameters of the lens. We present an approach to the problem of calculation of basic paraxial parameters and the third order aberration coefficients of compound optical elements analogical to classical lenses which are based on refractive tunable-focus lenses. A detailed theoretical analysis is performed for a simple tunable-focus lens, a generalized tunable-focus lens, a generalized tunable-focus lens with minimum spherical aberration, and three-element tunable-focus lens (a tunable-focus doublet).