LENS UNIT, ABERRATION CORRECTION ELEMENT AND DESIGN METHOD THEREOF

LENS UNIT, ABERRATION CORRECTION ELEMENT AND DESIGN METHOD THEREOF

PROBLEM TO BE SOLVED: To provide a lens unit which can focuses a laser beam within the focal depth even if the oscillation wave length of the laser source abruptly changes, and also provide an aberration correction element and a design method thereof. SOLUTION: This lens unit has a pickup lens, and...

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Hauptverfasser: KANAI TOMONORI, SUGI YASUYUKI, MIYAUCHI MITSUSUKE, MITSUI YOSHIKAZU, MAKINO YUTAKA
Format: Patent
Sprache:eng
Schlagworte:
INFORMATION STORAGE
INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER
OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
OPTICS
PHYSICS
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Zusammenfassung:PROBLEM TO BE SOLVED: To provide a lens unit which can focuses a laser beam within the focal depth even if the oscillation wave length of the laser source abruptly changes, and also provide an aberration correction element and a design method thereof. SOLUTION: This lens unit has a pickup lens, and an aberration correction element 14 which is positioned at the light source side of the pickup lens and has two or more level difference rings. The level difference rings have level differences to generate phase differences enough to focus the laser beam converged by the pickup lens within its focal depth when the wave length changes. COPYRIGHT: (C)2009,JPO&INPIT