Positive-negative tunable cylindrical liquid crystal lenses.

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]