Optical head apparatus for reading different types of recording mediums

摘要

An optical head apparatus is disclosed, that comprises a first optical system having a first objective lens (20) and a low power output laser device (24) and a second optical system having a second objective lens (30) and a high power output laser device (37). The focal length of the first objective lens (20) is different from the focal length of the second objective lens (30). One of these optical systems is selected corresponding to the type of an optical disc for use. The energy use efficiency of laser beam of the optical head apparatus with the above-described structure is higher than that of an apparatus using a multi-focus lens. Thus, without need to use a light source having a high light intensity, data of various optical discs can be accurately reproduced. In addition, data can be more accurately and rapidly recorded on various optical discs with different record densities.