Optical Properties of Anamorphic Liquid Crystal Microlenses and Their Application for Laser Diode Collimation

Anamorphic liquid crystal (LC) microlenses are fabricated using elliptical hole-patterned electrodes of various sizes and ellipticity. The relationships between their optical properties and electrode structure are investigated experimentally and summarized as follows. 1) The maximum values of the numerical aperture (NA) in the directions parallel and perpendicular to the rubbing direction simultaneously depend on the diameters in the direction parallel and perpendicular to the rubbing direction (D∥ and D⊥), respectively. 2)The normalized longitudinal aberrations, which are closely related to the spherical aberration, in the directions parallel and perpendicular to the rubbing direction strongly depend on D∥ and D⊥, respectively. 3)The astigmatism strongly depends on the ellipticity (D∥/D⊥) of the electrode pattern. Finally, an optical setup for collimating an astigmatic beam emitted from a laser diode (LD) is realized using an anamorphic LC microlens. As a result, a round collimated beam is obtained, and the potential of the anamorphic LC microlenses for collimating a laser diode beam is confirmed.