US Patent 7593308 Optical head device capable of detecting the output laser beam

The optical head device includes a semiconductor laser for emitting a laser beam having an elliptical beam shape; a collimator lens for collimating the laser beam emitted from the semiconductor laser; a reflector including pair of belt-like pieces one of the surfaces of which is used as a reflecting face formed in a curved face having a curvature along their longitudinal direction, the pair of belt-like pieces being formed to be arranged in a major axis direction of an elliptical beam flux to sandwich the optical axis of the laser beam, and an optical sensor equipped with a condenser lens for detecting the strength of the beam reflected from the pair of belt-like pieces of the reflector.