DIFFRACTION ELEMENT AND OPTICAL PICK-UP APPARATUS HAVING THE SAME

摘要

A diffraction element and an optical pick-up apparatus including the same are provided to control the inclination of a lattice pattern and to improve precision of the FE(Focus Error) signal. A diffraction element(160) is divided into the first area(162) and the second area(164) with a division line as the center. The division line is formed toward the tangential direction of a disc, that is, in parallel to the track direction. The first and second areas are slanted at the predetermined angles with respect to a virtual line vertically positioned to the division line. The lattice pattern of each pattern is formed alternately as much as 1/2 pitch. The diffraction element divides the light emitted from a light source into one main beam and two sub beams.