Liquid crystal adaptive lens: beam translation and field meshing

Physical limitations and fundamental factors affecting performance of liquid crystal tunable lenses with concentric electrode rings

A comprehensive analysis of fundamental factors and their effects on the performance of liquid crystal (LC)-based lenses is given. The analysis adopts numerical LC director and electric field simulation, as well as scalar diffraction theory for calculating the lens performance considering different variable factors. A high-efficiency LC lens with concentric electrode rings is fabricated for verifying and enriching the analysis. The measurement results are in close agreement with the analysis, and a summary of key factors is given with their quantitative contributions to the efficiency.

Switchable electro-optic diffractive lens with high efficiency for ophthalmic applications

Presbyopia is an age-related loss of accommodation of the human eye that manifests itself as inability to shift focus from distant to near objects. Assuming no refractive error, presbyopes have clear vision of distant objects; they require reading glasses for viewing near objects. Area-divided bifocal lenses are one example of a treatment for this problem. However, the field of view is limited in such eyeglasses, requiring the user to gaze down to accomplish near-vision tasks and in some cases causing dizziness and discomfort. Here, we report on previously undescribed switchable, flat, liquid-crystal diffractive lenses that can adaptively change their focusing power. The operation of these spectacle lenses is based on electrical control of the refractive index of a 5-mum-thick layer of nematic liquid crystal using a circular array of photolithographically defined transparent electrodes. It operates with high transmission, low voltage (<2 Vrms), fast response (<1 sec), diffraction efficiency > 90%, small aberrations, and a power-failure-safe configuration. These results represent significant advance in state-of-the-art liquid-crystal diffractive lenses for vision care and other applications. They have the potential of revolutionizing the field of presbyopia correction when combined with automatic adjustable focusing power.

Three-terminal adaptive nematic liquid-crystal lens device

A 1 mm x 1 mm nematic liquid-crystal three-terminal device for optical beam forming (focusing/spoiling) is fabricated. A thin-film-resistor network on the device substrate layer is used to control the voltages on the 98 internal lens electrodes by use of only one variable external driver. By using a high-resistance thin-film layer of amorphous silicon under the 98-element parallel electrode structure layer, we generate a near-continuous index perturbation to form a cylindrical lens. The focal length of this lens is continuously variable from inifinity to 12 cm by use of a variable 1-4-V-peak 1-kHz square-wave external terminal control signal.

Programmable coherent source arrays generated by spatial light modulators

Programmable coherent source arrays are generated by using addressable liquid-crystal spatial light modulators and two-dimensional arrays of Fresnel lenses. The modulators used are an optically addressed liquid-crystal light valve, a matrix-addressed pixelated display, and two devices that have individually addressable elements with specially designed patterned electrodes. One such device has a transparent electrode patterned as a Fresnel zone plate array; the other is a gate array used in a hybrid implementation with a Fresnel lens array etched on a glass substrate. The operation of devices that use binary-amplitude and binary-phase Fresnel lenses is described, identifying programmable features, resolution limits, and applications.