An optical head device may include a twin laser light source which is
integrally provided with a first laser beam emitting element and a second
laser beam emitting element, a light receiving element, and an optical
system including an objective lens for converging a laser beam on an
optical recording medium. The optical system is provided with a detection
lens structured of a toric lens. The toric lens applies an astigmatic
difference caused by a toric face to the one of the return light beams,
and the toric lens applies the other of the return light beams an
astigmatic difference caused by a toric face and astigmatism composed of
astigmatism and curvature of image field caused by passing off-axis
position to coincide a focusing position of the first laser beam with
that of the second laser beam.