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Optical pickup device

An optical pickup and beam technology, applied in optics, beam guiding devices, nonlinear optics, etc., can solve the problems of increasing the size of the optical pickup device, reducing the quality of recording or reading information, and high cost.

Inactive Publication Date: 2008-02-27
FUNAI ELECTRIC CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] When using an objective lens set in an optical pickup device supporting multiple types of optical recording media, since the thickness of the transparent cover layer for protecting the recording layer differs depending on the type of optical recording medium (for example, the thickness of the transparent cover layer of CD is 1.2mm, the transparent cover layer thickness of DVD is 0.6mm, and the transparent cover layer thickness of BD is 0.1mm), so there is a problem that the quality of recording or reading information is affected by spherical aberration in the optical system of the optical pickup device. reduce
Therefore, there arises a problem that the size of the optical pickup device is increased and the cost is high because it is necessary to increase the number of photodetectors according to the number of different optical path lengths.

Method used

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Examples

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no. 1 example

[0033] FIG. 1 is a schematic diagram showing an optical system configuration of an optical pickup device according to a first embodiment. The optical pickup device 1 according to this embodiment is provided to be compatible with BD / DVD / CD (optical recording media). The optical pickup device 1 includes a first light source device 2 , a second light source device 3 , a dichroic prism 4 , a beam splitter 5 , a collimator lens 6 , an objective lens 7 , a holographic element 8 and a photodetector 9 .

[0034] The first light source device 2 is a dual-wavelength integrated laser diode that has two light emitting points to emit light beams with two types of wavelengths, and this device emits a light beam with a wavelength of 780nm for CD and a light beam with a wavelength of 650nm for DVD . The second light source device 3 is a single-wavelength laser diode, and emits a light beam with a wavelength of 405 nm for BD. Light beams emitted by the first light source device 2 and the sec...

no. 2 example

[0052] Next, an optical pickup device according to a second embodiment will be described. The structure of the optical pickup device according to the second embodiment is the same as that of the optical pickup device according to the first embodiment except for the hologram element 8 . Therefore, only the structure of the hologram element 8 is described in the following sections. In addition, when there are overlapping parts in the embodiments, these parts will be denoted by the same reference numerals, and their description will be omitted when no specific description is required.

[0053] 6A and 6B are schematic diagrams showing the structure of hologram element 8 included in the optical pickup device according to the second embodiment. FIG. 6A is a schematic diagram showing a part of hologram element 8 , and FIG. 6B is a schematic diagram showing an electrode pattern of second transparent electrode 22 b of hologram element 8 . As shown in FIG. 6A, the hologram element 8 i...

no. 3 example

[0062] Next, an optical pickup device according to a third embodiment will be described. The structure of the optical pickup device according to the third embodiment is the same as that of the optical pickup device according to the first embodiment except for the hologram element 8 . Therefore, only the structure of the hologram element 8 will be described in the following sections. In addition, when there are overlapping parts in this embodiment, these parts will be denoted by the same reference numerals, and when no specific description is required, the description will be omitted.

[0063] FIG. 7 is a schematic diagram showing the structure of hologram element 8 included in the optical pickup device according to the third embodiment. In the same way as the second embodiment, the hologram element 8 according to the present embodiment also uses a liquid crystal element, but the liquid crystal is a holographic polymer dispersed liquid crystal (HPDLC) and its structure is diff...

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Abstract

An optical pickup device includes a plurality of light sources for emitting light beams having different wavelengths; an objective lens for focusing the light beams emitted from the light sources on a recording surface of an optical recording medium; and a photo detector for receiving the light beams reflected from the recording surface. The light beams emitted from the light sources include a first light beam and a second light beam having wavelengths different from each other, the first light beam is incident on the objective lens with a finite system, and the second light beam is incident on the objective lens with an infinite system, paths through which the reflected light of the first light beam and the second light beam reach the photo detector are common to each other, and a hologram element for compensating a focal position in an optical axis direction of one of the first light beam and the second light beam is disposed at a position through which only the reflected light beams pass and which is in front of the photo detector.

Description

technical field [0001] The present invention relates to an optical pickup device capable of reading and recording information by irradiating light beams on an optical recording medium, and more particularly to an optical pickup device having a plurality of light sources emitting light beams of different wavelengths, thereby supporting various types of optical recording Optical pickup device for media. Background technique [0002] Optical recording media including compact discs (hereinafter referred to as CDs) and digital versatile discs (hereinafter referred to as DVDs) are widely available. Also, in order to increase the amount of information recorded on the optical recording medium, research for increasing the density of the optical recording medium has been conducted in recent years. For example, high-density optical recording media such as Blu-Ray Disc (registered trademark; hereinafter referred to as BD) and HD-DVD are available in the market. [0003] Such recording...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G11B7/135G02F1/13
CPCG11B7/1376G11B7/1378G11B7/1275G11B2007/0006G11B7/13922G11B7/1353
Inventor 滨冈美佳藤井仁长岛贤治
Owner FUNAI ELECTRIC CO LTD
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