Patent ID: 7420897

Claim:
An optical head, comprising a light source, an objective lens for concentrating a laser beam emitted from the light source onto information tracks of an optical disk, and a light sensing device for sensing a luminous flux reflected by information tracks, wherein: the light sensing device includes a luminous flux incident area divided into a plurality of regions by a straight vertical dividing line passing an optical axis of the objective lens and parallel with a direction tangent to the information tracks, straight first and second horizontal dividing lines normal to the vertical dividing line and symmetrically arranged with respect to the optical axis, a first and a second partition lines symmetrically arranged between the two horizontal dividing lines with respect to the vertical dividing line while being distanced from the vertical dividing line and the two horizontal dividing lines, each of the first and second partition lines includes a pair of horizontal lines parallel with the two horizontal dividing lines, and an inner line connecting ends of the horizontal lines toward the vertical dividing line, the luminous flux incident area further includes an N region crossing over the vertical dividing line between the two horizontal dividing lines, one region partitioned between the two horizontal dividing lines by the vertical dividing line being divided into an A 2 region at a side toward the optical axis and a remaining A 1 region by the first partition line, and the other region partitioned between the two horizontal dividing lines by the vertical dividing line being divided into a B 2 region at a side toward the optical axis and a remaining B 1 region by the second partition line, the A 1 region and the B 1 region are symmetrically arranged with respect to the vertical dividing line, the A 2 region and the B 2 region are symmetrically arranged with respect to the vertical dividing line, and the optical head further comprises a tilt detector for detecting a relative tilt of the objective lens and the optical disk in accordance with a luminous energy incident on the luminous flux incident area of the light sensing device.