Patent ID: 7002893

Claim:
An optical pickup apparatus, comprising: a base; a light source provided on the base; a light detector provided on the base for detecting light emitted by the light source which is reflected by an optical recording medium; and a light separating device, divided into at least a first area and a second area, for separating the light incident on each of the first area and the second area into a plurality of light components and directing each of the light components in a prescribed direction, wherein the light detector includes a light receiver, divided into a first light receiving region and a second light receiving region, for receiving the light components directed by the first area of the light separating device, the first light receiving region and the second light receiving region are located so that a first direction is substantially perpendicular to a second direction, where the first direction is a direction of a phantom straight line connecting a light emitting point of the light source and a focal point on the light detector of the light transmitted through the light separating device, and the second direction is a direction of a dividing line for dividing the light receiver into the first light receiving region and the second light receiving region, a material of the base and a wavelength of the light from the light source are selected so that a distance of movement of the focal point on the light detector in a direction perpendicular to the second direction is within a prescribed tolerance limit, the movement being caused by a change in the wavelength of the light emitted by the light source and expansion or contraction of the base, which are both caused by a temperature change of the optical pickup apparatus, the light separating device being divided into at least the first area and the second area, wherein the areas have different grating pitches, by a dividing line which is substantially perpendicular to a tracking direction of the optical recording medium, and the light incident on the areas being directed to different light receiving regions of the light detector.