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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]

Polarizer-free imaging (PFI) methods have been proposed to address the problem of polarizer dependency of liquid crystal (LC) lens. PFI can generate images with high contrast, but will also raise the image noise. This paper presents a denoising method specially designed for the images generated by PFI, namely PFI denoising. The Salient noises and image textures can be accurately detected. Different denoising filters are then applied to different image regions. Good performance of PFI denoising is demonstrated by experimental results. [ABSTRACT FROM AUTHOR]

A method based on image processing is proposed to solve the problem of polarizer dependency of LC lens. No polarizer is required for imaging by the LC lens. In an imaging system with an LC lens, images Il and In are captured sequentially in lens and non-lens states of the LC lens, respectively. The final image I is obtained based on Il and In according to the equation I = Il - 0.5In. The proposal is tested experimentally. Clear and well focused images are obtained. [ABSTRACT FROM AUTHOR]

Abstract: A liquid crystal lens with focus movable in the focal plane is reported. There are three electrodes in the cell. One electrode with a hole in the center is divided into four subelectrodes. The potential of each subelectrode is adjusted to produce a desired asymmetrical phase transformation resulting in off-axis movement of the focus. The potential of another electrode is adjusted to maintain the focus in the focal plane. Movements of the focus in three directions in the focal plane are demonstrated experimentally, and off-axis movement as large as approximately 800μm is realized. [Copyright &y& Elsevier]

Liquid crystal lenses(LCL)of two liquid crystal(LC)layers with parallel and orthogonal optic axes are built. The LCL of two LC layers with parallel optic axes is designed to obtain larger focusing power, and that with orthogonal optic axes is to focus light wave of arbitrary polarizations. The focal lengths of both LCLs can be controlled by external voltages. [ABSTRACT FROM AUTHOR]

A liquid crystal lens with focus movable off as well as along the axis is realized. There are two electrodes in the cell: one with a hole, and another with resistance and subelectrodes. The focus can be adjusted along the axis by the applied voltage across the two electrodes, just as that in a conventional liquid crystal lens, and it can also be moved off the axis by the voltage across the subelectrodes. Electrical control of the movements of the focus in the two directions is demonstrated in the paper. [Copyright &y& Elsevier]

A method of improving the image quality of an optical system using liquid crystal lens is proposed and demonstrated by experiments. Because image magnification is invariant with liquid crystal lens imaging, an image processing using focused and defocused images can be done to enhance the contrast of the focused image. [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]

This paper reports a polarizer-free imaging method for an optical system that uses a liquid crystal (LC) lens of single nematic LC layer as a focusing element. By using a reference image, undesired low frequency image components introduced by non-modulated ordinary wave are reduced and the image contrast is enhanced. The proposed method is verified by experiments. Clear and well-focused images can be obtained without using any polarizer. [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]