Optimization of device parameters for minimizing spherical aberration and astigmatism in liquid crystal microlenses

The aberration properties of liquid crystal (LC) microlenses with various diameters, thicknesses and shapes (circles or ellipses) are evaluated by analyzing fringe patterns generated by interference between ordinary and extraordinary rays. It is found that the astigmatism and the spherical aberration can be minimized by adjusting the ellipticity of the hole pattern and the applied voltage, respectively. Based on the experimental results, we propose a design scheme for minimizing the spherical aberration and astigmatism. It is confirmed that the LC microlens obtained by the proposed design scheme shows a good focusing spot whose value of full width half maximum is close to that of the diffraction limit.