| 摘要 |
<p>An optical head device has improved reproduction qualities by efficiently detecting a reproduction signal having a low frequency noise component even at the time of reproducing data from a super-resolution optical disc including a small recording mark of a diffraction limit or smaller. An aperture control means (70) functions to reflection light from an optical disc (7) and makes the outgoing pupil diameter (D2) of an objective lens in a return optical path larger than an incoming pupil diameter (D1) in an outward optical path. Reflection light in a range larger than the incoming pupil diameter (D1) is detected by a light receiving element (11). Thus, the periphery of the reflection light having a low rate of low frequency noise component is efficiently detected by receiving light without using an objective lens having high NA and high manufacturing cost, and high quality reproducing signal is obtained.</p> |
