Liquid progressive multifocal lenses based on asymmetrical freeform surface structure using non-uniform thickness membranes

For a liquid progressive multifocal lens with an elastic membrane deformed by liquid pressure, to realize a reasonably power distribution, an asymmetric deformation characteristics of membrane surface is needed. Based on the asymmetric freeform surface structure, this paper proposed liquid progressive multifocal lenses focused by liquid with non-uniform thickness membranes and different boundary constraints. The structure and mathematical model of power distribution for the lens are introduced. The membrane deformation and the corresponding power distribution of the lenses with asymmetric freeform surface are predicted and compared under uniform pressure load and different boundary constraints. A membrane deformation testing system is constructed to analyze the power distribution of fabricated lenses through measuring the surface sag using laser displacement sensor and corresponding optical power distribution can be calculated. Experimental results show that the liquid lenses can realize as liquid progressive multifocal lenses after liquid accommodation, meanwhile, the trends of power distribution of the lenses generally agree well with simulations.