Optical system for optical disc apparatus including anamorphic prisms
AssigneeAsahi Kogaku Kogyo Kabushiki Kaisha
InventorsIsao Okuda, Suguru Takishima, Masahiro Oono, Koichi Maruyama, Masato Noguchi
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Abstract
An optical system of an optical disc apparatus is disclosed for converging and projecting a bundle of rays emitted from a light source onto an optical disc. The optical system includes a collimating lens which collimates the bundle of rays emitted from the light source, two anamorphic prisms for shaping the cross section of the collimated bundle of rays transmitted through the collimating lens, and an objective lens which converges the bundle of rays shaped by the anamorphic prisms onto the optical disc. At least one of the anamorphic prisms is detachably mounted to an immovable body portion of the optical system.
Claims21
An optical system for converging and projecting a bundle of rays emitted from a light source onto an optical disc, comprising:
- a collimating lens which collimates the bundle of rays emitted from the light source;
- first and second anamorphic prisms which shape a cross section of the collimated bundle of rays transmitted through said collimating lens, a refractive index of said first anamorphic prism being different than a refractive index of said second anamorphic prism
- an objective lens which conveys the bundle of rays shaped by said first and second anamorphic prisms onto the optical discs;
- and
- a substrate to which said first anamorphic prism is secured, and a mounting base which constitutes an immovable body portion of the optical system to which said first anamorphic prism is secured through said substrate, wherein said substrate and said mounting base are provided within an adjusting guide surface and an upright contacting surface which comes into contact with said adjusting guide surface to position said substrate and said mounting base, respectively.
An optical system of an optical disc apparatus for converging and projecting a bundle of rays emitted from a light source onto an optical disc, comprising:
- a collimating lens which collimates the bundle of rays emitted from the light source;
- means for shaping a cross section of the collimated bundle of rays transmitted through said collimating lens, said shaping means comprising first and second anamorphic prisms;
- an objective lens which converges the bundle of rays shaped by said shaping means onto the optical disc, said shaping means being detachably mounted to an immovable body portion of the optical system;
- and
- a substrate to which said first anamorphic prism is secured, and a mounting base, said mounting base comprising an immovable body portion of the optical system to which said first anamorphic prism is secured through said substrate;
- wherein said substrate and said mounting base are provided with an adjusting guide surface and an upright contacting surface which comes into contact with said adjusting guide surface, to position said substrate and said mounting lens;
- and
- wherein said adjusting guide surface of said substrate is substantially perpendicular to an optical axis of said first and second anamorphic prisms.
An optical system for converging and projecting a bundle of rays emitted from a light source onto an optical disc, comprising:
- a collimating lens which collimates the bundle of rays emitted from the light source;
- first and second anamorphic prisms which shape a cross-section of the collimated bundle of rays transmitted through said collimating lens, a refractive index of said first anamorphic prism being different than a refractive index of said second anamorphic prism;
- and
- an objective lens which conveys the bundle of rays shaped by said first and second anamorphic prisms onto the optical disc, wherein refractive indexes n.sub.1 and n.sub.2 of said first and second anamorphic prisms, an apex angle P.sub.1 of said first anamorphic prism, an angle .theta..sub.6 of refraction of said second anamorphic prism at an incident surface thereof satisfy the following relationship:
- 0.8.ltoreq.(n.sub.1 -1).multidot.P.sub.1 /(n.sub.2 -1).multidot..theta..sub.6 .ltoreq.1.25.
An optical system for converging and projecting a bundle of rays emitted from a light source onto an optical disc, comprising:
- a collimating lens which collimates the bundle of rays emitted from the light source;
- first and second anamorphic prisms which shape a cross-section of the collimated bundle of rays transmitted through said collimating lens, a refractive index of said first anamorphic prism being different than a refractive index of said second anamorphic prism;
- and
- an objective lens which conveys the bundle of rays shaped by said first and second anamorphic prisms onto the optical disc, wherein refractive indexes n.sub.1 and n.sub.2 of said first and second anamorphic prisms, an apex angle P.sub.1 of said first anamorphic prism, an angle .theta..sub.6 of refraction said second anamorphic prism at an incident surface thereof, variations .DELTA.n.sub.1 and .DELTA.n.sub.2 of said refractive indexes of said first and second anamorphic prisms corresponding to a change in wavelength, and an angular magnification .gamma. of said second anamorphic prism satisfy the following relationship:
- 0.8.ltoreq.(.gamma.n.sub.1 .multidot.P.sub.1 /n.sub.1)/(.DELTA.n.sub.2 .multidot..theta..sub.6 .multidot..gamma./n.sub.2).ltoreq.1.25.
Dependencies are inferred from the claim text.