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Optical pickup device

An optical pickup device, laser technology, applied in the direction of beam guiding device, optical recording head, recording/reproducing by optical method, etc., to achieve the effects of improving S/N, suppressing complexity, and suppressing cost

Inactive Publication Date: 2008-10-29
SANYO ELECTRIC CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

For this reason, the S / N of the signal output by the photodetector 57 cannot become a sufficient S / N for reproduction.

Method used

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Experimental program
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Effect test

no. 1 approach

[0036] FIG. 1 shows the configuration (optical system) of an optical pickup device according to the first embodiment. In the figure, 11 is a semiconductor laser (laser light source) that emits blue laser light with a wavelength of about 405 nm; 12 is a diffraction grating that divides the laser light from the semiconductor laser 11 into three beams; 13 is to reflect 90% of the incident laser light and make 10% transmission parallel plate non-polarized light reflector. The non-polarized light reflector 13 is arranged so as to be inclined at a predetermined angle (for example, 45°) with respect to the optical axis of incident laser light.

[0037] 14 is a collimator lens that converts the reflected laser light of the non-polarized light reflector 13 into parallel light; 15 is a 1 / 4 wavelength plate that converts the laser light passing through the collimator lens 14 into circularly polarized light; 16 is a polarization beam splitter .

[0038] 17 is the first objective lens th...

no. 2 approach

[0057] 5A and 5B show the configuration (optical system) of the optical pickup device according to the second embodiment. FIG. 5A is a plan view of the optical system from the semiconductor laser 31 to erected mirrors 36 and 42 , and FIG. 5B is a side view of the optical system after erected mirrors 36 and 22 . In addition, in FIG. 5B, the part of the lens holder 25 is shown in cross-sectional view for convenience.

[0058] In this figure, 31 is a semiconductor laser (laser light source) that emits blue laser light with a wavelength of about 405nm, and 32 is a 1 / 4 wavelength plate 32a and a diffraction grating 32b that convert the laser light from the semiconductor laser 31 into circularly polarized light. After the optical element, 33 is a polarizing beam splitter. Laser light emitted from the semiconductor laser 31 is converted into circularly polarized light by the 1 / 4 wavelength plate 32a. Therefore, 50% (P polarization component) of the laser light incident on polarizat...

no. 3 approach

[0077] This embodiment is a modified example of the first embodiment described above. That is, in the above-mentioned first embodiment ( FIG. 1 ), although the laser light is circularly polarized by a 1 / 4 wavelength plate and enters the polarized beam splitter 16, even if the polarized beam splitter 16 is Adjusting the polarization direction of the laser light in such a manner that the polarization axis is tilted can also achieve the same effect as that of the above-mentioned first embodiment. This embodiment relates to a configuration in which laser light from a semiconductor laser 11 is distributed to first and second objective lenses 17 and 19 by inclining the polarization direction of the laser light relative to the polarization axis of the polarization beam splitter 16 .

[0078] FIG. 6 shows the configuration of the third embodiment. In this embodiment, the 1 / 4 wavelength plate 15 in the first embodiment described above is replaced with a 1 / 2 wavelength plate 21 . Othe...

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Abstract

A quarter-wave plate and a polarization beam splitter are used as means for guiding a laser beam to first and second objective lenses. A half of the circularly-polarized laser beam incident to the polarization beam splitter is reflected in the form of an S-polarized light component by the polarization beam splitter and guided to a first objective lens, and the other half is transmitted through the polarization beam splitter in the form of a P-polarized light component and guided to a second objective lens. The whole of light quantity of the laser beam reflected from an optical disk through the first or second objective lens passes substantially through the polarization beam splitter. Therefore, the light quantity of the laser beam guided to a photodetector can be enhanced.

Description

technical field [0001] The present invention relates to an optical pickup device, and more particularly to an optical pickup device suitable for irradiating laser beams to different types of disks using a plurality of objective lenses. Background technique [0002] Compatible optical pickup devices that irradiate laser light to different disks are being developed in accordance with the diversification of disks. Among such optical pickup devices, optical pickup devices corresponding to Blu-ray Disc (hereinafter referred to as "BD") and HD DVD (High-Definition Digital Versatile Disc: hereinafter referred to as "HD"), because of the thickness of the cover layer of the disc and the Since the NA (numerical aperture) of the objective lens is different, two objective lenses corresponding to each disk are mounted. In this case, since the wavelength band of the laser light used is the same, it is desirable to configure a single semiconductor laser as a light source and distribute th...

Claims

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Application Information

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IPC IPC(8): G11B7/135
CPCG11B7/1356G11B7/1365G11B7/1374G11B2007/0006
Inventor 加纳康行大杉里美
Owner SANYO ELECTRIC CO LTD
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