| 摘要 |
AN OPTICAL PICKUP DEVICE WHICH CAN OBTAIN A STABLE REPRODUCTION SIGNAL BY AN INCREASED NUMERICAL APERTURE OF AN OBJECTIVE LENS. THE OPTICAL PICKUP DEVICE INCLUDES AN OBJECTIVE LENS UNIT (200) HAVING AN OBJECTIVE LENS (210) FACING A DISC (300) AND HAVING A PREDETERMINED EFFECTIVE DIAMETER AND AT LEAST TWO AUXILIARY LENSES (230) PROVIDED IN EXTERIOR SIDES OF THE OBJECTIVE LENS FOR DIRECTING +1ST-ORDER DIFFRACTED LIGHT TO A LIGHT PATH DIFFERENT FROM THAT OF THE LIGHT PASSING THROUGH THE OBJECTIVE LENS, A LIGHT SOURCE (800) FOR IRRADIATING LIGHT ONTO THE DISC THROUGH THE OBJECTIVE LENS, A LIGHT SPLITTER (400) INTERPOSED BETWEEN THE LIGHT SOURCE AND THE OBJECTIVE LENS FOR DIRECTING THE LIGHT REFLECTED FROM THE DISC TO A LIGHT PATH DIFFERENT FROM THAT FROM THE LIGHT SOURCE, A PHOTODETECTOR (600) FOR DETECTING THE LIGHT REFLECTED FROM THE DISC AND TRAVELLED VIA THE LIGHT SPLITTER, AND AT LEAST TWO DIFFRACTED LIGHT DETECTORS (610A, 610B) FOR DETECTING DIFFRACTED LIGHT INCIDENT FROM THE AUXILIARY LENSES. THEREFORE, A HIGH REPRODUCTION SIGNAL AND A STABLE TRACK SIGNAL CAN BE OBTAINED. (FIGURE 1)
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