Abstract
Further accurate focus error detection in an optical pickup which is applicable for a large capacity data storage such as Blu-ray Disc^<TM> (BD) was studied. In the focus error detection with a conventional astigmatic aberration method, an unexpected offset of the focus error is occurred due to either an optical alignment shift or a distortion of beam profile on the photo-detector. The reduction effect of the focus offset was confirmed on simulation, introducing an additional calculation term to correct the focus offset in the conventional astigmatic aberration method.
