With hole-patterned electrodes separated from liquid crystal layers it becomes possible to fabricate liquid crystal lens of
high quality and large size. The properties of the lens of this kind of electrode structure are discussed. The modifications
to the original structure to realize lenses of improved quality, that are polarization-independent and having focus
movable in focal plane are also discussed.
A novel optical manipulation system for controlling three-dimensional positions and rotation of
trapped microscopic rods is proposed by using a liquid crystal (LC) device with unique functions such as
an anamorphic lens property in addition to both variable-focusing and deflection properties. Arranging
the control voltages of the LC optical device, the laser beam can be focused with any elliptical cross
section. The trapped slender object is aligned along the rotatable major axis of the elliptically shaped
laser beam spot and can be shifted three-dimensionally.
A two-voltage-driving technique is applied to build liquid crystal (LC) lens and LC microlens. One bias voltage is fixed and the other one varies to control the focal length of the LC lens or the LC microlens. The range of the variable focus is wide, and in the entire focus range the optical quality is preserved. The application of the LC lens as a focusing lens for cameras is demonstrated.
Studies on the liquid crystal lens with curved electrode are reported. The lens power is dependent on the applied voltage, and the lens size is nearly that of the curved electrode and therefore can be changed arbitrarily. The influences of material property and lens geometry on the properties of the LC lens are studied numerically. The properties of the lens of different geometries are investigated experimentally.
Several types of liquid crystal (LC) lenses with variable focusing functions by applying an external electric field have been reported. We propose a new type of LC lens using the molecular orientation effects and resulting elastic force of LC director. The hole-patterned alignment area is treated for LC molecules to align parallel or perpendicular to the substrate coated with transparent electrodes, and outside area is treated to be an inverse alignment state. The surface of another substrate is coated with a homeotropic alignment layer. When the diameter of the hole pattern is nearly equal or less than the LC thickness, the distribution of the refractive index becomes bell-shaped and the LC cell behaves like an optical lens in the absence of the applied voltage. The focal length can also be varied by applying a voltage across the transparent electrodes.
We propose a laser manipulation (optical tweezers) system for controlling microscopic objects by using a liquid crystal (LC) optical device with variable focusing and beam deflection properties. The focused spot, that is the position of the trapped particles can be controlled and moved by the change of the optical properties of the LC optical device by applying the voltage to the LC cell.
Liquid crystal (LC) lens with voltage and azimuth dependent focus is realized by using divided electrode structure. By applying appropriate potentials on the divided electrode, the LC cell behaves like an optical lens having astigmatic properties; the phase retardation of an incident light beam takes an elliptical shape in the cross-section. The axes of the elliptical shape of the phase retardation are electrically controllable.
First, a new method of voltage application is proposed. With the new drive method, disclinalion lines do not appear in the cell. Secondly, a liquid crystal lens with focus moveable along and off the axis is reported. The movements of the focus are controlled by the potentials of electrodes and sub-electrodes in the cell.
A detail description of a new liquid crystal lens is presented. The focal length of the lens is a function of the applied voltage. The working mechanism of the liquid crystal lens is explained. The lens acts as a magnifying glass is demonstrated as an example.
Optical properties in the liquid crystal (LC) microlenses are studied on molecular orientations with large and axially symmetrical electric field. The LC microlenses with a thick LC layer are also investigated by experiments and simulations of 3 dimensional finite difference method (3D-FDM). The LC microlens has a converging property with low applied voltage as well as a diverging property with high applied voltage. The dependence of converging property on D/t is investigated in the LC microlenses, where D/t is the ratio between a hole-pattern diameter D and LC thickness t, and the simulation by the 3D-FDM in terms of the molecular orientation state is successfully carried out. It is found that the lateral distribution of the LC molecular orientation in the thickness direction is not uniform and changes depending on the D/t ratio, and good converging properties can be obtained when the D/t value is around 2.
Numerical simulation of temporal evolution and spatial distribution of directors in a liquid crystal (LC) microlens is presented. We show that splay deformation and twist deformation obtained for the LC microlenses with a pre-tilt angle and without one are quite different. Details of director orientation in both types of LC microlenses are discussed.