OPTICAL PICKUP

PURPOSE:To obtain a compact and light-weight optical pickup with low cost by using an objective lens and an aspherical lens together with a Fresnel zone plate serving as an optical element which divides a reading luminous flux into two parts. CONSTITUTION:A Fresnel zone plate 17 contains two concent...

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Bibliographic Details
Main Authors WAKABAYASHI RON, MIYAKE YOSHIO, KASAHARA KUMIO, TATSUMI KENJI, HASHIMOTO TSUTOMU
Format Patent
LanguageEnglish
Published 06.05.1987
Subjects
INFORMATION STORAGE
INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER
OPTICAL ELEMENTS, SYSTEMS, OR APPARATUS
OPTICS
PHYSICS
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Summary:PURPOSE:To obtain a compact and light-weight optical pickup with low cost by using an objective lens and an aspherical lens together with a Fresnel zone plate serving as an optical element which divides a reading luminous flux into two parts. CONSTITUTION:A Fresnel zone plate 17 contains two concentrical diffraction gratings connected to each other on a flat substrate with the grating spaces reduced gradually toward the circumferential area from the center of the two concentrical circles according to a prescribed rule. Then a transparent part and an opaque part are provided on the substrate with the prescribed thickness respectively. The laser luminous fluxes dispersed from a light source 1 like a laser diode, etc. are made incident on the plate 17 and the transmitted 0-order light is condenced on the pit surface of a disk 5 through an aspherical plastic objective lens 16. Then the read luminous flux is condensed by the lens 16 and made incident on the plate 17 to be divided into two parts.
Bibliography:Application Number: JP19850238057