An Advanced Active Optical Pickup with Crossed-Stripe Liquid Crystal Device for Compensation of Spherical Aberration

Abstract

To increase recording density in an optical disk system, increasing the numerical aperture (NA) is one effective method. But when NA becomes larger, the spherical aberration due to disk thickness error increases. We propose an optical pickup with a spherical aberration compensator using nematic liquid crystal (LC). Our LC device is composed of two LC cells each of which has X and Y stripe electrodes, respectively. We have actually fabricated the device and have confirmed that the desired property was achieved. We have also confirmed that the laser beam was modulated by the LC and was successfully focused.