Patent ID: 6445668
Filing Date: 2002-09-03
Classification: G11B

Abstract:
An optical pickup device comprising:a photodetector divided into four light-receiving elements by two substantially perpendicular dividing lines; an incident optical system for irradiating a light beam onto an optical recording medium, the incident optical system including a light source for irradiating an incident light beam and an object lens for concentrating the incident light beam onto the optical recording medium and a hologram optical element, the light source, the object lens and the hologram optical element arranged on a first optical straight axis; and a receiving optical system for guiding a return light from the optical recording medium to the photodetector, the receiving optical system including the hologram optical element for deflecting the return light toward the photodetector and for generating astigmatism having an astigmatism axis fixed at an angle of 45 degrees with respect to the two dividing lines, the hologram optical element and the photodetector arranged on a second optical straight axis defining a different direction than the first optical straight axis.