METHOD FOR GENERATING FOCUS ERROR SIGNAL, APPARATUS FOR GENERATING FOCUS ERROR SIGNAL, OPTICAL HEAD AND OPTICAL DRIVING APPARATUS

摘要

PROBLEM TO BE SOLVED: To provide a method for generating a focus error signal which is free from loss of light quantity of the signal and provides an inclination of a desired tangent range and a desired detection range for the focus error signal.;SOLUTION: To generate a focus error signal: a light beam is divided into at least two light beams; coma aberration in a predetermined direction is added to one of the divided light beams; and coma aberration in a direction different from the predetermined direction is added to the other divided light beam.;COPYRIGHT: (C)2013,JPO&INPIT