| 摘要 |
<p>An optical head device is provided with at least one start up mirror (30), a plurality of objective lenses (7, 14), an objective lens actuator (13) and a moving mechanism (33). The start up mirror (30) permits a luminous flux, which has a prescribed wavelength and emitted from semiconductor lasers (1, 9), to enter and changes its direction. The objective lenses (7, 14) have different numerical apertures, condense the luminous flux the direction of which is changed by the start up mirror (30), and irradiate an information recording medium (8). The objective lens actuator (13) moves the objective lenses (7, 14) in a focus direction of the information recording medium (8) to have the luminous flux entered the information recording medium (8) focused. The moving mechanism (33) moves the start up mirror (30) to have the luminous flux enter the information recording medium (8) through one of the objective lenses (7, 14).</p> |
