Patent ID: 8050167

Claim:
An optical device comprising: a wiring substrate; a sub-mount where an onboard part for mounting a semiconductor laser thereon and an optical-path conversion mirror for reflecting laser light emitted from the semiconductor laser are integrated with each other, the sub-mount being arranged on the wiring substrate; a light receiving element substrate arranged on the wiring substrate; and a light receiving element arranged on the light receiving element substrate and divided into a plurality of light receiving regions by a first parting line substantially parallel to a tangential line of a recording track of an optical disc projected on the light receiving element substrate and a second parting line perpendicular to the first parting line, wherein the sub-mount is arranged on the wiring substrate so that a longitudinal axis of the sub-mount is inclined to the tangential line of the recording track in view from an upside of the optical device, whereby at least one of: a long axis in cross section of light flux, which is emitted from the semiconductor laser, further reflected by the optical-path conversion mirror and further irradiated toward the optical disc; a short axis in cross section of the light flux; and a linear polarization of the light flux, is substantially neither parallel nor perpendicular to the first parting line and the second parting line, thereby making an predetermined angle to the first parting line.