Analysis of Light Fields Formed by a LC Focusing Device with Application to Problems of Three-Dimensional Optical Manipulation

Abstract

The formation of light fields of various structure and real-time control of their parameters with the help of inexpensive and technologically simple adaptive devices is an urgent problem of modern optics. A 4-channel liquid-crystal (LC) modulator (LC focusing device) can serve as such a device. An analysis of longitudinal light lines and hollow light beams formed by this device is performed. Such fields are realized due to the possibility of creating a phase delay distribution over the aperture of an LC focusing device in the form of a truncated cone (quasi-axicon). Spatial and energetic characteristics of these light fields are considered from the standpoint of their potential applications in problems of three-dimensional manipulation. It is shown that by varying the voltages applied to the contacts of the focusing device it is possible to control the width of the light contour, the size of the zero-intensity region, the lengths of the light tube and light line segment, and the energy characteristics of the formed fields. The results obtained may be of use in the formation of three-dimensional optical traps in problems involving the manipulation of transparent and nontransparent micro-objects.