| 摘要 |
A partial beam focus sensing device comprises a lens element (20; 30; 40; 70) receiving a collimated light beam (12) reflected from optical recording media, and a light detector array (26; 46; 76). A centrally symmetric mask element (16; 100) adjacent to the lens element illiminates a portion of the light beam and transmits a partial light beam. The light detector array comprises at least two light detector elements (26a, 26b; 46a, 46b) mathced to the mask element and disposed to receive the partial beam from the lens element. |
