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An electrode pattern design generating a parabolic voltage distribution, in combination with usage of the linear response range of the liquid crystal (LC) material, has been recently proposed to obtain nearly ideal phase profiles for LC lenses. This technique features low driving voltages, simple structure, compact design, and the absence of high-resistivity (HR) layers. In this work, the universal design principle is discussed in detail, which is applicable not only to LC lens design, but also to other LC devices with any phase profile. Several electrode patterns are presented to form a parabolic voltage distribution. An equivalent electric circuit of the LC lens based on the design principle is developed, and the simulation results are given. In the experiments, an LC lens using the feasible parameters is prepared, and its high-quality performance is demonstrated. [ABSTRACT FROM AUTHOR]

We propose a design method for liquid crystal lens with positive-negative tunable focal length and rectangular aperture. The designed electrodes produce a parabolic profile of voltage difference over the lens aperture. Parabolic phase profile is then obtained by controlling the voltage difference within the linear response range of liquid crystal materials, and high-quality performance liquid crystal lens can be realized. The principle of the design is described and the lens is demonstrated experimentally. [ABSTRACT FROM AUTHOR]

This paper describes how the maximum blur radius affects the depth results by depth from the defocus (DFD) method based on liquid crystal (LC) lens. Boundary frequency is determined by the maximum blur radius. It is found that if the maximum blur radius used in the calculation is larger than the real value, the depth resolution obtained is reduced; on the other hand, if one smaller than the real value is used, the depth resolution in the middle range of the scene is increased, but errors occur in the near and far planes. Using the maximum blur radius close to the real one results in the best depth results. [ABSTRACT FROM AUTHOR]

An imaging system is designed with a liquid crystal (LC) lens as the focusing element. The aperture of the LC lens plays the role of the aperture stop of the system. An entrance pupil larger than the LC lens aperture is realized and the magnification of the image formed by the system remains unchanged when the focal length of the LC lens is changed by the applied voltages. [ABSTRACT FROM AUTHOR]

Optical powers and RMS aberrations of the LC lens with different cell gap are studied. With increasing cell gap, the LC lens exhibits similar relation between the optical power and the driving voltage, and the RMS aberrations increase with optical power. The maximum optical power of the LC lens within the aberration level of 0.07 wave and the corresponding driving voltage are nearly proportional to the cell gap. [ABSTRACT FROM AUTHOR]

A new method of voltage application is proposed to increase the focus range of a liquid crystal lens driven by two voltages. It is possible for the optical power of the liquid crystal lens to change in a wider range, while the root mean square aberration of low level is maintained. The liquid crystal lens is driven by a frequency of the voltages different in positive and negative lens states to obtain its largest optical power in each state. An obvious increase in focus range is realised. [ABSTRACT FROM AUTHOR]

The primary objective of this study is to design a cylindrical liquid crystal lens with ideal phase profile, which also overcomes the associated drawbacks of current cylindrical liquid crystal lenses, such as high driving voltages, numerous voltage sources, and complex manufacturing processes. By designing the shape of the indium tin oxide electrode, the parabolic distribution of the resistance is realized, thereby forming a parabolic voltage distribution. The driving voltages are controlled within the voltage range that the phase of liquid crystal layer responds linearly to voltage, so a parabolic phase profile is obtained. The designed indium tin oxide electrode is developed by photolithography. The phase profiles are extracted from interference fringes obtained by use of polarization interferometry. The phase profile maintains parabolic during focus tuning, a positive-negative tunable cylindrical liquid crystal lens with near-ideal phase profile is demonstrated experimentally. The full width at half maximum of normalized intensity at focal plane is smaller than the corresponding diameters of Airy disks, which means the positive lens has a good focusing effect. The negative lens expands the beam to about twice its original width, it is in accordance with the principles of geometrical optics. • Nearly ideal phase profile in the whole focus range (inherent parabolic phase profiles). • The focal length is positive-negative tunable, thus doubling the possible optical power. • Linear relation between the optical power and the driving voltages. • More flexible in design because the voltage profile is produced by the circuit unit outside the lens area. • Easy for mass production. [ABSTRACT FROM AUTHOR]

Transient properties of a liquid crystal (LC) lens are investigated. It is shown that the LC lens maintains its lens properties as it is driven to switch between positive and negative lens states. Its optical power changes from positive to negative values and rms aberration also changes with time but always keeps below 0.1 wavelength. This transient property of the LC lens is made use of to acquire image of extended depth of field. [ABSTRACT FROM AUTHOR]

We use a liquid crystal (LC) lens to create a foveated imaging system which contains a camera module as a main lens, an LC lens as a foveated device, and an image sensor. The principle and experimental results are given. The influences on imaging of the parameters, including the position and aperture of the LC lens, and the aperture of the lens module, etc, are discussed. [ABSTRACT FROM AUTHOR]