Objective lens for optical pickup device, optical pickup device, and optical information recording/reproduction device

An optical pickup device and information recording technology, which is applied to optical recording heads, optical recording/reproduction, data recording, etc., and can solve problems such as increased step difference and changes in diffraction efficiency

Inactive Publication Date: 2013-08-21
KONICA MINOLTA INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

In addition, it has also been found that in the superimposed structure in which the diffraction structure shown in Patent Document 1 is superimposed, the step difference in the optical axis direction increases, so that large fluctuations in diffraction efficiency when the wavelength is changed are likely to occur.

Method used

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  • Objective lens for optical pickup device, optical pickup device, and optical information recording/reproduction device
  • Objective lens for optical pickup device, optical pickup device, and optical information recording/reproduction device
  • Objective lens for optical pickup device, optical pickup device, and optical information recording/reproduction device

Examples

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Embodiment 1

[0250] The objective lens of embodiment 1 is a plastic single-chip lens. A conceptual diagram of the first optical path difference imparting structure of Example 1 is shown in Image 6 . ( Image 6 Different from the actual shape of Example 1, it is a conceptual diagram after all) The first optical path difference imparting structure of Example 1 is a blazed diffraction of (2 / 1 / 1) in the entire area of ​​the central area The optical path difference providing structure of the 1st base structure BS1 which is a blazed diffraction structure of (1 / 1 / 1) is superimposed on the 2nd base structure BS2 of a structure. Moreover, the level|step difference of 2nd foundation structure BS2 faces the direction of optical axis OA, and the level|step difference of 1st foundation structure BS1 faces the direction opposite to optical axis OA. Furthermore, the average pitch of the first foundation structure BS1 is smaller than the average pitch of the second foundation structure BS2, and the nu...

Embodiment 2

[0257] The objective lens of embodiment 2 is a plastic single-chip lens. Conceptual diagram of the first optical path difference imparting structure in Example 1 and Image 6 same. The first optical path difference imparting structure of Example 1 is to superimpose (1 / 1 / 1) The optical path difference imparting structure of the first base structure BS1 of the blazed diffraction structure. Moreover, the level|step difference of 2nd foundation structure BS2 faces the direction of optical axis OA, and the level|step difference of 1st foundation structure BS1 faces the direction opposite to optical axis OA. Furthermore, the average pitch of the first foundation structure BS1 is smaller than the average pitch of the second foundation structure BS2, and the number of steps facing the direction opposite to the optical axis of the first foundation structure is smaller than that of the second foundation structure facing the direction of the optical axis. Many. In the 1st foundation...

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Abstract

Provided are: an optical pickup device and optical information recording / reproduction device provided with an objective lens capable of improving temperature characteristics and wavelength characteristics while making it possible to support three types of optical disc, namely Blu-ray Discs, DVDs, and CDs, with a shared objective lens; and an objective lens suitable therefor. A first optical-path-difference creation structure, in which at least a first basic structure and second basic structure are superimposed, reduces a step difference in the optical-axis direction, thereby keeping the diffraction efficiency from decreasing upon wavelength changes. Furthermore, when the wavelength of incident light increases, spherical aberration from the aforementioned first basic structure and second basic structure changes in the direction in which more correction is needed; thus, when the index of refraction of the objective lens changes as a result of an increase in the temperature of the optical pickup device, the fact that the wavelength of the light source also increases as a result of the increase in ambient temperature is utilized to correct spherical-aberration degradation due to the change in the index of refraction of the objective lens.

Description

technical field [0001] The present invention relates to an optical pickup device, an objective lens, and an optical information recording and reproducing device capable of recording and / or reproducing information (recording / reproducing) interchangeably with different types of optical discs. Background technique [0002] In recent years, in the optical pickup device, the laser light source used as a light source for reproducing information recorded on the optical disc and recording information on the optical disc has been shortened. For example, blue-violet semiconductor lasers have a wavelength of 390 to 420 nm. Laser light sources are being put into practical use. When using these blue-violet laser light sources, in the case of using the same numerical aperture (NA) objective lens as DVD (Digital Versatile Disc), it becomes possible to record information of 15 to 20 GB on an optical disc with a diameter of 12 cm. When the NA of the optical element is increased to 0.85, it ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G11B7/1353G02B13/00G11B7/127
CPCG02B27/0025G11B7/1353G11B7/1367G11B7/1374G11B7/13922G11B2007/0006G11B7/1275
Inventor 田中秀树中村健太郎立山清乃
Owner KONICA MINOLTA INC
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