Optical lens with electrically variable focus using an optically hidden dielectric structure

Abstract

Electrically variable gradient index liquid crystal lens is developed that uses flat uniform liquid crystal layer and electrodes. The spatial modulation of the electric field across the lens aperture is obtained by the modulation of the effective dielectric constant of an integrated doublet lens structure. The dielectric constants of two materials, composing the doublet, are chosen to be different at electrical driving frequencies, while their optical refractive indexes are the same, hiding thus the structure from the optical point of view. This "hidden layer" approach decouples the electrical and optical functions of that structure, increases significantly the performance of the lens and enables new functionalities. The technical performance and various driving schemes of the obtained lens are presented and analyzed.

Liquid-crystal photonic applications

“…44 Figure 8(c) shows a different approach that is nowadays succesfully used in autofocus cameras in cell phones. 45 The LC layer is again homogeneous, but due to the use of two different dielectric materials with different dielectric constants, the electric field in the LC layer is different at different positions. The refractive index of the dielectric materials are matched, so the LC layer itself fully incorporates the optical functionality, while the two dielectric materials take care of the electric functionality.…”

Liquid Crystal Microlenses for Autostereoscopic Displays

“…Moreover, the lens power of LC lenses is not only electrically tunable, but it can also be positive or negative, which has interest for ophthalmic lenses. In this case, lenses with millimeter diameter are required [46]. Liquid crystal lenses can correct myopia impact.…”

Focusing unpolarized light with a single-nematic liquid crystal layer

“…6 Many approaches have been demonstrated to also build nematic LC (NLC) components for optical imaging. 1,[7][8][9][10][11][12][13][14][15][16][17] However, those materials have a fundamental limitation: they are polarization sensitive since the refractive index modulation here is achieved by the electrical field-induced reorientation of their local anisotropy axis (commonly called "director," representing the local average direction of the long molecular axes of the NLC 4 ). Figure 1(a) schematically demonstrates an electrically variable NLC lens using a single-layer of NLC that is in the Y; Z plane (with its ground state director being parallel with the Y-axis).…”