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Objective lens, optical pickup device, recorder and reproducer

A technology of optical pickup and objective lens, which is applied in the direction of optical recording/reproduction, optical recording head, optics, etc., and can solve problems such as replay/record misoperation of optical information storage media

Inactive Publication Date: 2004-01-14
KONICA CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Misoperations involving playback / recording for optical information storage media may occur when glare light enters the sensor

Method used

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  • Objective lens, optical pickup device, recorder and reproducer
  • Objective lens, optical pickup device, recorder and reproducer
  • Objective lens, optical pickup device, recorder and reproducer

Examples

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example 1

[0164] Table 3 shows the diffraction index of the second-order diffracted light and the diffraction index of the third-order diffracted light in the case of optimizing the diffraction index of the third-order diffracted light of DVD in the peripheral area. Figure 4 is the axial spherical aberration diagram of DVD. Figure 5 is the axial spherical aberration diagram of CD.

[0165] In this case, on the optical axis direction of the diffraction structure, the depth Δd of the diffraction structure on the peripheral region of the objective lens 16 is represented by the following formula:

[0166] Δd≥3×λ 1 / (1.54094-1).

[0167] like Figure 5 As shown, when the wavelength λ 2 When the beam of =785nm entered the objective lens 16, in the beam passing through the second zone (the zone where the numerical aperture exceeds NA2=0.470), the second-order diffracted light crosses the optical axis, and is far away from the focal point than the third-order diffracted light. It can be ...

example 2

[0169] Figure 4 It shows the diffraction index of the third order diffracted light and the diffraction index of the fourth order diffracted light when the diffraction index of the fourth order diffracted light of DVD is optimized in the peripheral area. Image 6 is the axial spherical aberration diagram of DVD. Figure 7 is the axial spherical aberration diagram of CD.

[0170] In this case, in the direction of the optical axis of the diffractive structure, the depth Δd of the diffractive structure on the peripheral region of the objective lens 16 is represented by the following formula:

[0171] Δd≥4×λ 1 / (1.54094-1).

[0172] like Figure 7 As shown, when the wavelength λ 2 When the light beam of =785nm enters the objective lens 16, among the light beams passing through the second zone, the third-order diffracted light crosses the optical axis, and is farther away from the focal point than the fourth-order diffracted light. It can be seen from Table 4 that the diffrac...

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Abstract

It is to provide an objective lens for being provided in an optical pickup device for firmly carrying out the reproduction / record for each of a plurality of optical information storing media in which the protect substrates have different thicknesses from each other. The optical functional surface of the optical lens is divided into the central region including the optical axis and the peripheral region arranged outside the central region. The diffractive structure is provided on the peripheral region. When the reproduction and / or the record is carried out for the first optical information storing medium, the diffracted light is condensed on the focal point. When the reproduction and / or the record is carried out for the second optical information storing medium, among flare lights in which diffracted lights having various diffraction orders and passing through the peripheral region are mixed, the diffraction efficiency of the K-th order diffracted light is larger than the diffraction efficiency of the (K-1)th order diffracted light which causes a larger aberration than the K-th order diffracted light.

Description

technical field [0001] The present invention relates to an objective lens used in an optical pickup for recording and / or reproducing information on a group of optical information storage media whose protective substrates have different thicknesses; relates to an optical pickup; a recorder and a replay current equipment. Background technique [0002] With the practical use of short-wavelength red lasers, DVD (Digital Versatile Disc), a high-density optical information storage medium (also called "Compact Disc") having the same size and high capacity as CD (Compact Disc), has been commercialized. [0003] In a CD recording / reproducing apparatus, when a semiconductor laser emitting light having a wavelength of about 780 nm is used, the numerical aperture NA on the disc side of the objective lens is about 0.45. On the other hand, in a DVD recording / reproducing apparatus, when a semiconductor laser emitting light having a wavelength of about 650 nm is used, the numerical apertur...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G11B7/00G11B7/125G11B7/135
CPCG11B7/1378G11B7/1381G11B2007/0009G11B2007/0006G11B7/1275G11B7/13922G11B7/1356G11B7/1353
Inventor 本田浩司
Owner KONICA CORP
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