US Patent 7394746 Optical head apparatus and optical information processing apparatus

To reduce the optical path length of the entire optical system in a reproduction or recording optical system of an optical recording medium, and promote miniaturization and reductions in costs of apparatuses. An optical head apparatus has an optical system an including a light source and a translucent optical element and irradiates light exiting from the light source, after having been transmitted through the optical element, onto the optical recoding medium. The optical element has a surface or surfaces having negative power on the light-source side and a surface or surfaces having positive power on the optical-recording-medium side. In order to increase the power of the surface or surfaces, one or more of these surfaces are formed as a hologram surface on which a concentric hologram pattern is formed.